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We’re very proud of Make: Electronics, the beginner’s guide to electronics written by MAKE contributing editor Charles Platt. It has consistently been an O’Reilly bestseller and has already been through several printings. It’s a hit! It seems to fulfill the exact purpose we set for it, which was to basically be a truly accessible, plain-spoken, visual beginner’s guide to electronics for the early hours of the 21st century. If you’re new to electronics and interested in diving right in, experimenting with components, and then learning about the theories behind them (a process Charles dubbed “learning by discovery”), you really should check out this book.

To give you a chance to do just that, we’re running a giveaway, thanks to our pals in the Maker Shed. To be eligible, all you have to do is tell us in comments what’s the biggest nagging question you have about electronics. Are you wondering in which direction electrons actually flow? What all of those little letters after “V” (voltage) are for on a circuit diagram? What the third power post on a common breadboard is for? What flux is all about? No question is too basic. And after the drawing, we’ll try and answer as many of these questions as we can. If you don’t have any questions, you can help (and be eligible for the drawing) by answering questions or sharing some interesting information about electronics that beginners might benefit from.

We’ll be giving away five (5) copies of the book. Deadline for comment entries is 11:59pm PST, Wednesday, Jan 26th. Winners will be announced on Thursday morning. Good luck.

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Make: Electronics
Want to learn the fundamentals of electronics in a fun and experiential way? Start working on some excellent projects as soon as you crack open this unique, hands-on book. Build the circuits first, then learn the theory behind them! With Make: Electronics, you’ll learn all of the basic components and important principles through a series of “learn by discovery” experiments. And you don’t need to know a thing about electricity to get started.

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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Comments

  1. Kenneth Finnegan says:

    As DIP packages become less and less common, how are we going to respond? Is PCB etching and surface mount soldering just going to become another requirement of electronics, or will breakout boards for every chip become a competitive enough secondary market to keep us going?

    Why is Electroboards the only company I can find selling good general-purpose SMD breakout boards?

  2. Matt Silvia says:

    I get the relationship between voltage, current, and resistance, but I don’t know how to do anything more interesting with it than light up a bulb or make a motor spin. Even then, I’m not confident I won’t set fire to anything, and while I’m not afraid to tinker (and have actually fixed some electronic via basic troubleshooting), complex circuits make me feel like I’m missing out on the secret handshake.

    I guess I know how a capacitor works… I just don’t know why you would want one. If this book would lift the shroud of confusion and get me on track to building and modding, I’d love a copy!

    1. HowTutorial says:

      There is a bit of a secret handshake. Electronics is a vast field that can appear quite overwhelming. But ohm’s law is part of the secret, so you are off to a great start. Further more, much design is individual circuits chained together. Then tweak your circuit empirically, and how it all works together becomes harder to see.

      So how do you know if you are going to start a fire or not? Ohm’s law says the voltage equals the current multiplied by the resistance. So with any two of these, you can calculate the third. Power equals current times voltage. By lowering resistance, for the same voltage, you have increased the current. So you have increased the power. Put a wire with very little resistance across a battery, then the wire and battery will get hot. The wire might melt. (try a 9 volt battery on steel wool) But if the battery gets too hot, it might pop, exposing you to the nasty chemicals inside or worse. So be careful when you play with fire.

      For your next question, there are many uses for a capacitor. A capacitor is made up of two conductive parts that are not touching. If you put a voltage across a capacitor, positive and negative charge will build up on it’s two sides, with charge on one side attracted to the opposite charge on the other side. If you remove the external voltage, the capacitor will still have the charge you gave it. That charge across a capacitor creates a voltage of it’s own. The voltage is the same as that external voltage that we just removed. So a capacitor stores voltage. If you put a resistor across the capacitor the charge will flow through the resistor to the opposite charge on the other side of the capacitor. The larger the capacitor, the more charge you can bleed off this way before you run out of charge, and thus reduce the voltage to zero.

      Continuing, using ohm’s law we can calculate the initial current through the resistor. That current through the resistor creates a voltage across it equal to what the capacitor holds. That voltage holds back more charge from flowing. So the resistor limits the speed of the capacitor discharging. The smaller the resistor, the faster the charge discharges. A new law to know is the RC time constant. The resistance multiplied by the capacitance equals the time it takes for the voltage to drop 63%. It will take the same amount of time to drop the next 63%, and so on. This also works going the other way, and charging a capacitor through a resistor. It will take one RC time constant to charge 63%.

      So a capacitor tries to maintain it’s voltage. The larger the capacitance, the larger the time constant, and the slower the change in voltage. So one use of a capacitor is to reduce fluctuations in the voltage in part of a circuit. So you can use a capacitor to quiet the noise on a power supply. The noise is the fluctuations you don’t want. Similarly, if you put capacitors across the power pins of IC’s, you can create more stable power for all your chips.

      There is much more, but this is getting long, and I am typing on my iPad.

      1. ferretdad says:

        As others have pointed out, capacitors store energy in electric fields, and inductors store energy in magnetic fields. But it’s also useful to think of them as resistors — but very odd resistors.

        Capacitors are like resistors that decrease in value with frequency. For “DC” (non-changing) voltages, they have infinite resistance; for very high frequencies, they have very low resistance. Thus if one were to replace the lower resistor in a resistor divider with a capacitor, one would get a divider network in which the lower resistor looked very big for low frequencies and very small for high frequencies — this is a low-pass filter. You will often see them used this way in power supplies.

        Inductors are like resistors that _increase_ in value with frequency. For “DC” voltages, they have almost no resistance; for very high frequencies, they have a very high resistance. If you substitute an inductor for the _upper_ resistor in a divider network, you _also_ get a low-pass filter — and again, you will often see them used this way in power supplies.

  3. Aequitarum Custos says:

    Why must they be color coded?

    I’m colorblind, and would prefer to just read the numbers on them.

    If there is a place I can purchase Numbered resistors, I’d greatly appreciate it.

    A magnifying glass is much better than asking a friend to help me with a hobby they have no interest in, or using my Color Guessing program on my phone, which has had limited success (though not completely useless).

    1. StayatHomeElectronics says:

      You may look into surface mount resistors. Although there are the obvious connection differences, which can be overcome by being creative, many have the value written right on them, especially the larger sizes. Look into 0805 and 1206 sizes. Anything smaller becomes much more difficult to handle.

    2. Alan says:

      My color vision is fine, but I seldom bother decoding the color bars on resistors. You should have a digital multimeter handy anytime you’re working on electronics, so just set it to ohms and measure the resistor you’re holding. The only times I’ve bothered with the color codes are when I’m teaching the concept, or when I’m sorting a large number of resistors from a mixed package. Otherwise, it’s much quicker to just measure.

      And as the previous reply mentioned, surface-mount resistors dispense with this silly color code entirely (though you’ll need a powerful loupe to read the tiny digits on them).

  4. Upir says:

    I’ve always wondered exactly how a wire carries information along. I understand it’s electrical pulses along the wire, but what converts it to information that can be received by the user? If it’s a simple on/off thing then what was the point of anything beyond binary since the wire would only essentially be carrying binary signals of yes and no, off and on.

    1. HowTutorial says:

      Have you ever played telephone with two paper cups and a string? This article does a good job of explaining the game and how it relates to electrical signals:
      http://science.howstuffworks.com/question410.htm

      A wire can carry a changing voltage. The speed of change and the magnitude of voltage are two ways varying information can be transmitted on a wire. With the invention of the microphone we have a direct way of converting sound to an electrical signal. The invention of the speaker converts the electrical signal back to sound.

      Did I give you an intuitive feeling for how a signal can be more than on and off?

  5. d.moonfire.us says:

    How and why do you use a capacitor, in specific with power supplies? I occasionally see a diagram that needs it but not really more than “used as a surge protector” or “just a good idea”.

    1. KentD says:

      In a power supply converting AC to DC, there is always a big capacitor on the output to smooth the voltage. Without it, the voltage would be a 120 cycle per second of pulses, and they would come through on any audio as a buzz. It also acts as a reservoir of electrons for time when the circuit uses more current than the power supply can make.

    2. xrazorwirex says:

      Capacitors are actually extremely critical components and they do a lot of different things. When you put AC across the cap it will charge up during the rise and discharge during downswing, which will smooth out the pulse.

      It’s not able to convert AC to DC or anything (we use diodes for that) but you can use it to turn a choppy line into a solid DC voltage or you can use it with an inductor (which is basically the opposite of a capacitor) to make filters that clip out specific frequencies (in audio).

    3. Vicki says:

      Capacitors are neurotic little devices that don’t like change (in voltage).

      For example, a bypass capacitor is the one that usually hangs off your circuit and goes to ground and seems to have no purpose. Because capacitors can hold a reserve of charge, they release that charge to try and fill any little dip and keep a constant voltage and shunt extra energy out.

      Filter capacitors are usually paired with a resistor and attenuate signals outside a frequency range determined by the values of the components.

      Coupling capacitors are placed in-line to a signal path so only the AC signal (eg a sine wave) can pass through, but the DC component (eg an offset or bias voltage) is blocked.
      This is used if your signal is going into a device that can’t handle a high voltage well. It’s common in between amplifier stages.

      I hope that helps a little and is ok info!

  6. Erik Jenkins says:

    One of the things that fascinate me most about electronics is the ability to not only amplify sound but also effect the way it sounds.

    One of the things I’d love to learn about electronics is how amplifiers work, so . . . . How do they work? How do we effect the way an electric guitar sounds?

  7. nimicohgr says:

    Why can we see electricity when it arcs across two wires, but are normally unable to see it?

    1. KentD says:

      You can never see electricity, just as you can’t see wind. You can only see the effects. Sometimes electricity causes heat, and the heat produces light. In other cases, the electrons interact in more interesting ways with matter: When an electron falls from one level to a lower level in an atom, it emits a photon, a particle/wave of light.

  8. Timur Tabi says:

    I’ve always been confused by inductors. I could never figure out what they’re for, or when I would want one in a circuit.

    1. xrazorwirex says:

      Inductors generally work with caps. They’re coils that when you have voltage across them they build up a magnetic field and “eats up” voltage and when the voltage goes away the field collapses and creates a burst of voltage.

    2. HowTutorial says:

      An inductor is a device that resists a change in current. For another question, I explained how a capacitor resists a change in voltage. If you put the two together in parallel, you create a resonant circuit. Energy stored as voltage in a capacitor will want to flow through the inductor as current, but the inductor resists this. An initial current will be low, but will then grow with time. The voltage meanwhile falls to zero. At this point the inductor has stored energy in a current. So continuing, this current flows into the capacitor, with the voltage starting at zero and eventually growing to be the reverse/negative voltage that we started at. Except for losses to resistance in the components, the process continues in reverse.

      This is an oscillation in a resonant LC circuit. The size of the inductor L and capacitor C effect the natural frequency of the oscillation. If you put an external oscillating signal to an LC circuit, like pushing on a swing, the closer the natural oscillation frequency is to your external signal frequency, the larger the voltage/current signals can flow through it. When you go farther away in frequency, the signal is lower. By adjusting the L or C, you can tune to new resonant frequencies.

      A tunable LC circuit is useful for selecting a particular frequency radio station with a radio receiver circuit.

  9. Shiftingchords says:

    Really, I wanna know what milliamps are all about.

    If I have 2 9v power supplies and one is 100ma and the other is 500ma, what does that mean? If I plug a 500ma supply into a device that is rated for 100ma what kind of damage would it do to the device if any? Also what is the main function? Are they a seperate part of a power supply circuit or just a measurement that is not always looked at?

    1. KC_Bigman says:

      mA rating is the current that the power supply can supply. If you you plug a 500mA device into a 100mA supply, you could blow the supply and damage the device. The purpose of the rating is so that you know that the power supply will provide a specific amount of current at the rated voltage.

    2. HowTutorial says:

      Your 9 volt power supplies are limited in how much current they can put out before the voltage falls too much to be usable. A device rated at 100ma will work with both your 100ma limited supply, or your 500ma limited supply. Your 500ma limited supply can handle 5 of these 100ma devices at once, while the smaller supply can only supply the one device.

  10. driph says:

    What is the history of the color coding system? How did it come about?

    1. bent-tronics says:

      Not sure about the history, but it involves the colors of the rainbow – ROYGBIV (http://en.wikipedia.org/wiki/Roy_G._Biv).

      For me it makes remembering values a lot easier, because I only need to remember 4 out of the 10 colors: All I remember is Black is Zero (low end of the scale), Brown is One, then ROY G BV, then gray, then White (high end of the scale) is Nine.

  11. Nate Koch says:

    I have a basic understanding of most things electronic, but really am at a lost as how to put it all together to make more complex circuits. Hopefully this book will help.

  12. killbox says:

    Ive been baffled by trying to make a simple capacitor charged blinking led circuit that runs off of 1.5v(got that to work but) what i want is when increasing resistance on one part of it, the light blinks faster. ive only been able to do the inverse, make it blink slower.

    1. EvilGenius121 says:

      you’re circuit is right, but by increasing resistance, electricity is taking longer to fill the cap, thus making the light blink slower. I you want it to blink faster, decrease the resistance. A 1k potentiometer hooked up right would do this pretty well and give you a pretty good range of values

  13. mike says:

    Im still trying to learn all of this stuff, every time i look at a circuit im trying to understand the flow. But they seem to break off and there seems to be multiple points between the + and the -

    is this normal? how does this not weaken the power in the device? Does this create a circuit within a circuit? And am i over thinking it at this stage?

    1. HowTutorial says:

      On your car, you have headlights, taillights, radio, ignition, starter, etc. They are all individual circuits connected in parallel to the battery. When you turn the key to start the car, some of these other circuits are temporaraly disconected from the battery. So the overall car schematic has interaction between subcircuits. The starter motor uses so much power that disconecting the other subcircuits leaves more battery current capacity to do the job. This is especially important if your battery is low on charge.

      So, yes, your power supply or battery has limits to how much power it can supply. Adding more circuits in parallel will discharge the battery quicker, and create a voltage drop through resistance in the wires and battery itself. If you load the battery too far, the voltage will drop below the designs of the circuit.

  14. jonnyz says:

    If you can run so much current through a circuit before it starts heating up from resistance, why isn’t this factor used and circuit materials engineering done more, or heard of? Couldn’t energy be shaped with facts like these? Wires with energy flow could be shaped in a similar to car engines.

  15. jonnyz says:

    If you can run so much current through a circuit before it starts heating up from resistance, why isn’t this factor used and circuit materials engineering done more, or heard of? Couldn’t energy be shaped with facts like these? Wires with energy flow could be shaped in a similar manner to car engines.

  16. https://me.yahoo.com/a/8e3xDjw02OjmGT7P8Hh77Wu9uRkj3CcC#4c5f1 says:

    why can computers only use binary? Wouldn’t it be theoretically possible to use a .5 in addition to 0 and 1? Instead of on and off, on half on, and off, maybe even more middle values.

  17. mollymillions says:

    I’m with Matt and d.moonfire – I think get what a capacitor is (basically) and how it works (sort of), but I don’t really understand what it’s *for*….

    Also, what is the “water analogy” representation of a capacitor?

  18. Tupaschoal says:

    I’m kinda new at this so I wonder, what does arduino has that made it so popular?

    1. Steve Murphy says:

      1. Arduino is easy to get started with. You don’t need expensive tools, programmers and parts, you just hook it up and go.
      2. Arduino is inexpensive. You can get an Arduino for $20-30. Comparable board can cost from $50 up.
      3. Arduino is open source. All the software, the language, and even the hardware itself is open source. So the software is free and the hardware is cheap.
      4. Arduino has an active community. There are thousands of people in the Arduino community and lots of projects out there that you can use as a starting point for your own unique projects.
      5. Arduino is easy to program. One of the tools is a programming language that is similar to well known languages like C/C++ and Java.

      There is lots of interest in the Arduino, even by non-technical folks. In fact, Arduino was first created as a way for Artists to add electrical controls to their creations.

      1. Tupaschoal says:

        Thank you bro, just one more question, Arduino is only a brand that creates boards by getting components together or it makes its componentes like µC, crystals and others.

        1. Steve Murphy says:

          Arduino the trademarked name of an open source development board and associated open source tools to program it (including a language). Only the original team makes official Arduino boards, all 3rd party boards–even the ones that are identical to the original–can only be called “Arduino Compatible.” It used to cost hundreds of dollars and hours of effort to get your first LED to blink. Now for $20 you can buy a compatible board, plug it in to an $8 breadboard, hook up a battery and you’re in business in 10 minutes. Arduino has democratized the technology, making it available to the general public, where before you practically had to be an electrical engineer to get anything at all done. Arduino is based on the popular Atmel AVR series of microcontrollers.

          1. Tupaschoal says:

            Thank you man I think I’m ready to enter arduino community now =) .

  19. Caleb Bell says:

    I read about them, and they seem obvious, then in a few days they seem so complex and mysterious again. It is very frustrating, if only I had more time to dedicate to such things! I am sure this book would help me!

  20. nunforgivn says:

    I’m in high school and trying to teach myself electronic through books. Two of my biggest problems/ frustrations is using conversions and formulas between energy, voltage, power etc. and also knowing when to use certain values of a component (ei. resistors or capactors)

    1. Vicki says:

      Good question, unfortunately it’s a longish answer…

      Your basic equation is
      OHM’S LAW: V = I*R
      that is Voltage = Current * Resistance.

      Boring and meaningless. Let’s do an example:
      An LED needs about 30mA (30*10^-3 Amperes) to light up, and you have a 9V battery. What value resistor do you need?

      Start with V=IR and rearrange to solve for R = V/I.
      9V/30mA = 300-ohm resistor.

      So the circuit is: +Battery Terminal -> 300-ohm -> (+) LED lead (-) -> -Battery Terminal

      Before we connect it together, let’s make sure we’re not going to blow up our Resistor (Let’s assume our 300-ohm is rated for 1/4 Watt).

      Power = Voltage*Current (P = V*I)
      V and I can be substituted for using Ohms Law, for example:
      P = (I*R)*I
      P = V*(V/R)

      We have 9V and 30mA, so P = (9V)*(30mA) = 0.27-Watts
      P = (9V)^2/(300-ohm) = 0.27-Watts
      Whoa! That’s a little more than our 1/4-Watt resistor can handle! Let’s play it safe.

      You can fix this by putting resistors in parallel (||) to dissipate the power. The current will split across the two resistors coming in, and join back up on the other side so it acts like one resistor.
      Resistors in parallel:
      REquivalent = 1/((1/R1) + (1/R2))

      So, (after setting up a quick calculator in Excel), you look at your kit you pick a 500-ohm and an 820-ohm.
      Your Req = 311-ohm,
      quickly you calculate the current, I = 9V/311-ohms = 29mA Great!

      Quick power calculation to check:
      R1: P = (9V^2)/(500-ohm) = 0.162-Watt OK
      R2: P = (9V^2)/(820-ohm) = 0.099-Watt OK

      Good to go!

      (Alternatively, you select a 5-V battery and a 200-ohm resistor for 25mA of current and 1/8-Watt of power!)

      Whew! I hope that helps a little bit with your equation question, and gives you an easy project to test the equations!

  21. loumsc says:

    How do lasers read the Oxygen levels in the blood?

    1. npkeith.myopenid.com says:

      The oxygen probes I use at work use LEDs, not lasers, but the concept is still the same. Hemoglobin carries oxygen in the blood. Each molecule of hemoglobin can carry 4 atoms of oxygen. As hemoglobin becomes more saturated with oxygen, it becomes a brighter red color. The probes use a combination of a red LED and an infrared LED on one side and receptor on the other side. The light shines through a body part (usually a finger or toe, but an earlobe or nose will work too), and differing amounts of light make it out of the other side. By looking at the difference in the absorbtions of the 2 wavelengths, an oxygen saturation can be calculated.

  22. MakerMike says:

    I understand they store electricity, But I can’t seem to understand how to select one.

  23. Trent Nix says:

    Shamefully, I can do the math as I’ve studied electricity and magnetism in college level physics, but I never actually learned how to apply that knowledge in any tangible way. So really, what is everything I need in order to get started building solutions with electronics and related components?

  24. andyfriedl.myopenid.com says:

    I undersand there are red diode lasers and even infra red lasers. I was wondering if there is an ultra violet laser could be used for etching or burning.

  25. Jeff says:

    When do I use a bipolar transistor and when do I use a MOSFET? I know MOSFET’s are used in most modern electronics, so why would I use a bipolar transistor?

    1. Vicki says:

      BJTs can output a higher current and are current-controlled device (need a current-driver).

      MOSFETs are voltage-controlled. They have a larger bandwidth (switch faster), are stable over temperature and generally introduce less distortion.

  26. andyfriedl.myopenid.com says:

    I’d love to learn about the Arduino and the ability to test and build circuits.

  27. winslomb says:

    How do diodes stop current from reversing? I know that it acts like a check valve, but how exactly do they do it?

    1. xrazorwirex says:

      They’re made of two different materials, designated P and N.

      A diode is a sandwich of P and N materials; a transistor is just a diode with another amount P or N material layered on in addition (making it either NPN or PNP).

      Think of P material like a grate with holes in it and the N material as a valve mechanism that fills the holes. (correct me if I’m backwards on this, community :)

      When current flows from N to P the “valves” are pushed into the P material and locks off current flow. You still get some leakage (should be about .7 volts but special Zener diodes can leak a specific amount, like 5v) but for the most part the valve is shut. If the current flows the other way then the N material isn’t ‘clogging’ the P material and so it flows freely.

      Hope my layman explanation helps.

      1. HowTutorial says:

        If I understand your explanation, I think some of this is backward. Instead of valves, the N material has loose electrons. When the electrons flow from N to P, the electrons fill the holes in the P material, and jump from hole to hole continuing the current.

        When the diode is reverse biased, the loose N electrons and P holes are pulled apart at the barrier, and current no longer flows. If you put a large enough reverse bias voltage, two types of breakdown can occur. Electrons that were held in their bonds, finally have enough force to break free, and conduct in the reverse bias direction, and in Zener diodes quantum mechanical tunneling allows a current. Regular diodes can be damaged by this because of overheating, but Zener diodes are built for this and have adequate heat sinking. Zener diodes are also designed to breakdown at a particular voltage.

  28. madsci says:

    I’ve always seen a resistor connecting to the base of a BJT – if you’re just turning it on and off, do you really need this, or can you connect an IC logic pin directly to the transistor base?

    I’ve also had trouble finding a complete V-I curve. What happens when you reverse-bias a BJT? Does it act as a diode and block E/C current? Does current flow through the base?

    1. StayatHomeElectronics says:

      Always connect a resistor to the base of the BJT. A BJT is a current controlled device, i.e. the amount of current going into the base of the transistor controls the amount of current going through the collector.

      When the transistor is ON the voltage from the base to the emitter, V(be), will only get to around 0.7 volts. If you put a logic level, 5 volts, across the base-emitter junction you will damage the device.

  29. hugoestr says:

    Hi,

    This actually gets me confused, since I keep reading conflicting information. Yes, it was in the prompt, but I do wish to get an answer to this.

    Should I follow the schematic from negative to positive or from positive to negative?

    I know that electricity flows from negative to positive, but on British sources they say that schematics are written assuming a positive to negative flow. Later on, they said that it didn’t really matter.

    Now, if you have diodes, it seems to me that it does matter. A diode is doing something very different depending on which direction the electricity is actually flowing, or at least I assume that.

    So which way should I read them?

    1. KentD says:

      Thank Ben Franklin. He assumed current went one way, and so he labeled it as from positive to negative, as in from more to less, with 2 kinds of charge that like to be in balance. This is known as “conventional current”. It wasn’t until they started to understand the atom that they realized that he guessed it backwards. Since the electrons were moving the wrong way, they had to assign them negative charge. This is “electron current”. In any case until you look at the operation of the semiconductors, conventional current is ok.

      1. hugoestr says:

        So most schematics are written in conventional current then?

        1. Steve Murphy says:

          Yes, schematics assume conventional positive current flow. I like looking at circuits this way because the arrows on the diodes point in the direction of positive current flow. However, I recently read that electronics Instructors are split on which way to teach the subject. In fact the author of the article had taugt it one way for years and then changed to the other! One thing to do would be to get a good book (like Art of Electronics) and use the system used in your book.

  30. Thehoboprince says:

    What do inductors do in circuits and what is their heat and mechanical equivalents?

  31. bluke says:

    I understand what a memristor is, but I don’t quite understand how it works. I have heard many bold claims to the future potential of this amazing circuit element and would love to know how it does what it claims it can do.

    It would also be neat to know the application of the memristor for the DIY community and how it would make things better for us, the makers.

  32. Pete Prodoehl says:

    Is the Arduino the modern equivalent of the Apple ][? The piece of hardware that is helping to spark a revolution by making electronics accessible to people the same way the Apple ][ made computers accessible to people?

  33. El Gato Cranko says:

    I’d like to second hugoestr’s question about how to read schematics – I always somehow manage to make a horrible mess of circuits while trying to decipher them.

    1. EvilGenius121 says:

      I have similar question, i have a schematic with electrolytic caps. I have a schematic with the symbol for a cap. Its just the 2 little bars, but instead of them either being both filled out or left empty, one is black and the other is white. I thought the white part was negative (like the stripe on a cap) but Idk, and ive looked but cant find an answer. I can reference the datasheet if youd like :)

  34. Keator says:

    Ok, simple enough question but I imagine it can have very different answers.
    What is the best educational project for a beginner, where do start learning through practical application and what is the project that teaches the core skillsets?

  35. Tjs3000 says:

    How do you know when to use a pull down resistor?

  36. EvilGenius121 says:

    I just started arduino related projects and have about a million questions… I have an lolsheild, i don’t really know how to program it, or how it works.. I mean i get how to make a basic multiplexed (i hope i used the right word) screen, but how would that work with arduino? Shift registers also baffle me. What exactly do they do? How do they work? I want to do big projects, maybe a 4×4 LED cube, and once that is mastered, maybe the huge 8×8. I have tried a few large projects, but whenever i do, they usually don’t work. And yes, most of my errors are on a component level. And what exactly is an inductor? Wire wrapped around a core to produce magnetic fields, which re used for what? I hope MAKE doesn’t mind that i downloaded all their circuit skills episodes and put them on my ipod, they’re a real help :)
    So yeah, i have a lot more than one question.. i could go on for a long time but since i need to have one question, how about how a transistor works, it has always bothered me and i bought a few, but do not know how to get them to work :)
    Thanks for the giveaway MAKE! You rock!

  37. Scott says:

    Where should a HS freshman start who wants to ‘jump in with both feet’ to the world of electronics?

  38. Rajay says:

    I do not get the difference between them or understand what they mean. I still can solder stuff and make it work. LOL

    1. KentD says:

      Basic electronics uses basic, algebra 1 level math. Ohms law is the most important rule: amps=volts/ohms. (They usually use other symbols for the parts, I=E/R, but here I am using the units for simplicity.) Volts are the pressure of the electricity. Amps are the flow of electrons. Ohms is the resistance to flow. So Ohm’s law just says, “The flow is equal to the pressure divided by the resistance”. Some form of that applies to most things, like cars, or even politics.

  39. dbank says:

    I was wondering if the arduino clones can perform all of the functions that an original one can I would love to get involved with the arduino but am confused on what one to purchase and if I should get a starter set and then what kit to buy I do have the getting started with the Arduino book Also a easy explanation to Ohms Law would be great. Thanks

  40. wwench says:

    Don’t even know enough to ask an intelligent question! But electronics looks cool and I’d like to learn.

  41. EvilGenius121 says:

    wondering the same :)
    i mean its not like theres some tiny monkey in there stopping the current :)
    you know, i cant remember where i got that quote from…

  42. Schazamp says:

    Do you know any mnemonics (or other mechanisms) for remembering the different kind of 555 timer circuits (astable, monostable, etc.) and what timing patterns they have? I always have to look it up and read the details to figure out which one is meant.

  43. tgmake says:

    What’s sad is that even though I took physics and an intro to electrical engineering class in college, I never really understand how and why components were chosen for a circuit when looking at a the diagram. Basic questions like “why is that resistor between that capacitor and ground?”, or “why aren’t all of the pins on the IC being used?”

    With this book, I hope to be able to answer more of these questions on my own.

    1. hugoestr says:

      I am a beginner in electronics, but maybe we can apply the same technique that many use to learn a new programming language. After learning basic concepts, they find problem that they have to solve using that knowledge. Then you get a concrete reason for using different components.

      So maybe you should try to create a small circuit that does something specifically. I don’t know, maybe a snooze light that gets dimmer after a certain amount of time. Then start thinking which components you can actually use.

  44. TAC says:

    I would love to learn more about manipulating electrical circuits and different components that can be added to produce more sophisticated arduino projects!

  45. Jess says:

    I would really like to understand exactly how high and low band-pass filters work.

  46. JPB606 says:

    When do I use a ceramic, electrolytic, film, etc?

    1. Justin Myers says:

      I’d also be interested in learning this part.

    2. Vicki says:

      Ceramic caps (disks – very common) are not polarized, meaning they don’t care where the +/- of the circuit is. That makes them great for most applications, especially AC. If you have frequency components that need coupling/decoupling these are usually a good place to start. These are your basic workhorses.

      Aluminum Electrolytics (cans – very common) are polarized. They care very much that their +pin is connected to the most + node, and their -pin is connected to the most – node (eg ground). Large capacitance-per-volume making them great big charge-storage devices that can handle higher currents. These are super in power supply circuits for smoothing. They tend to come easily in larger values than the ceramics.

      Tantalum caps are another kind of electrolytic. They have great frequency characteristics. These are very sensitive to voltage direction and ratings, and not ideal for repetitive charge/discharge cycles. They will blow up if mistreated. If the circuit doesn’t specifically call for them, don’t worry about it.

      Film caps are high performance components, really great in high-frequency applications. Wound film caps are inductive, and stacked film caps have low inductance. Unless the circuit specifically calls for films, don’t worry about these either.

      Hope this helps a little ^_^.\/.

  47. SlashBlank says:

    How do you use all the functions on a multimeter?

    Is cold soldering better than hot?

  48. dan cooney says:

    My son has a great desire to make things that do awesome & fun things. I want to learn the basics of electronics and building boards, so I can teach my son, so we can make cool electronic gizmos together. I want to learn to use the right components for the job in a general way, so we can solve problems we come up against.

  49. michael says:

    How can I successfully replace my rechargeable batteries with gold caps?

  50. ppphhhh says:

    What is the difference between Voltage and Current, and how is it NOT analogous to plumbing?

    1. Jason Wier says:

      Voltage is the potential to do work: Like an object above the ground.

      Currenty is the transfer of that energy to the lower potential.

      The two together give power.

      1. EvilGenius121 says:

        A different way to say it (another version of a plumbing analogy) that is clearer to me is a set of speakers. Think of them playing some tones at a set volume. The frequency of the sound would be the voltage, but the volume would be the current. You could have a high frequency sound (higher voltage), but very low volume (low current), or a very low frequency (voltage), but enough volume to shake the floor (high current).
        Hope this helps :)

  51. josiahritchie.myopenid.com says:

    How do I trouble shoot why a project would work fine until a pot reaches a certain point and then it stops responding?

  52. amieg says:

    How can I successfully build a fiber optic link between a digital analog signal through the use of a phototransister? I am wanting to prevent lightning from damaging the digitizer on the other end of the fiber link. I have built one before successfully but I have lost my schematics and it seems no one can see my concept but me!

    Thanks,
    Amie

  53. Aaron Spike says:

    What is impedance matching and what are the effects of mismatched impedances?

  54. Fusei says:

    I’m somewhat new to this whole thing. I bought a breadboard and some components recently and managed to build a circuit from a diagram, and it was pretty cool. I actually have two questions. How are you supposed to use a multimeter in a circuit without breaking said circuit, and how exactly do transistors work? I saw the Make Skill Set article a while ago and I still don’t understand.

  55. kongorilla says:

    I have to re-learn electronics every time I do a project. I’d blame it on middle age, but this has been going on all my life. So, my nagging question is: Why is remembering electronics knowledge like trying to remember how to re-attach Spock’s brain after using the “Teacher” helmet?

  56. punkysfan says:

    so I understand the basic components like resistors, pots, transistors and the like. But my question is what in those black chips that make them work ,magic, gremlins. what is the AVR core, whats in an FPGA its so mysterious no ever explains whats in them just how to use them. I guessing you have to encase them in epoxy to make sure whatever is in them doesn’t get out.

    1. Vicki says:

      Those ICs or Integrated Circuits I think you speak of are generally regular circuits! It’s true! They are just really, really tiny components usually printed on silicon dies. These gremlins, excuse me, dies are encased in epoxy to protect them, and provide something to solder to.

      “Cores” are usually code for “Microprocessors” or “Microcomputers” – control centers that give commands and process data.

      FPGAs are Field-Programmable-Gate-Arrays. A fancy way to say computer-controlled-logic-circuit. These chips generally have a bunch of logic gates (AND, OR, XOR…) that you can “wire” together in different ways by loading a hardware description program before runtime. They can be programmed and reprogrammed with different configurations to do things logic circuits would do – but without busting out the soldering iron.

      Hope that helped a little!

  57. mda says:

    Newbie too.

    A long time ago in high school, I learned the basics of reading a diagram but I really need to review what all those symbol mean again.

    Batteries, resistors, and switches I remember. But what’s that triangle and those coil-y things?

    1. Vicki says:

      The triangle with a perpendicular line at the end is usually a diode of some kind. An LED if it has squiggly arrows going away from it.

      A plain triangle might be an amplifier.

      Coils are usually inductors. If they’re parallel to each other with a gap in between, they indicate a transformer

      http://www.kpsec.freeuk.com/symbol.htm

  58. Idlewood says:

    Ok, I get the gist of how a capacitor works, but I don’t understand how they work in a practical circuit. Ok, you can hook up a battery to it, fill it with electrons and connect its two ends together to release those electrons, but how can you plug it in to a circuit in a way that it will both fill up AND release without having to, say, flip a switch or otherwise interact with it.

    If I’m not making any sense, what’s been bugging me is a diagram in Mim’s “Getting Started In Electronics”–the metronome to be exact. It uses a cap and a couple of transistors. The cap acts as a timer for the metronome, filling up and dumping out at regular intervals. What I don’t understand is how the current flows one way and then starts flowing the other way once the cap is full. Why doesn’t the cap just fill up and block any more current indefinitely? How does it get around the voltage of the battery that charged it in the first place?

    1. HowTutorial says:

      That is not a beginner’s circuit to understand.

      My understanding is R1+R2 charges C1. That is the longest part of the cycle. When C1 is charged to above the on threshold of Q1, Q1 turns on, which turns on Q2, which puts a current through the 8 ohm speaker. The speaker voltage (SV) spikes up now that Q2 is on to almost 9 volts. The base voltage of Q1 is the sum of the speaker voltage (SV)and the C1 voltage, and it now also approaches 9 volts. Since Q1 is on, the base voltage drops quickly. C1 has a near 9 volt negative voltage across it in order that SV of 9 volts plus C1 equals Q1 base voltage. When base voltage drops to the threshold, Q1 shuts off. Q2 now shuts off. The speaker turns off. The voltage on the speaker drops. The base voltage is still the sum, and it drops to near negative 9 volts. Q1 is off, so C1 charges through R1+R2 again. The cycle repeats.

      So the capacitor’s ability to resist change in voltage allows us to create negative voltages in this circuit. Pretty cool.

      So how did I figure this circuit out? I simulated it in spice. I used the free LTspice IV from Linear Technology.

  59. casaheil says:

    This looks like a great book to get my kids ramped on electronics.
    Great Job!
    — Steve

  60. barrytrujillo says:

    If everything is neutrally charged by “default” then how can there ever be any charges transmitted? I guess my question is why and how friction causes electrical charge to be transmitted or does it create electrical charge?

  61. melanieca says:

    I have a pile of old electronics in my office that I’ve been saving to use as projects to learn about electronics. Problem is I have next to zero knowledge and experience so not sure where to start! Okay, real problem is procrastination but this book sounds like just what I need :)

  62. amhou.wordpress.com says:

    I don’t know how to install a crystal into an Arduino to make a clock!

    1. EvilGenius121 says:

      depends on what you want. if you have a pre made arduino (arduino uno etc. or something with a crystal already in it) you can program it to wait a certain amount of time with delay(milliseconds) (though accuracy may vary depending on temp and other variables). if youre looking for a clock circuit like this (http://www.sparkfun.com/products/99), its harder to program and read (idk how yet) but it doesnt lose youre data once you switch it off. you could build one for not too much $$
      note that both of these options are not super accurate, the real time clock can gain or lose up to 2 seconds a day
      hope this helps a little :)

  63. spottybanana.com says:

    We know some basics, but always want to learn more! For example, is there a special soldering iron required to remove components from a computer’s motherboard? We’ve been told that some manufacturers use special solder to meet ROHS requirements.

  64. melstergirl.myopenid.com says:

    I am an art student with an interest in electronics and have always wondered … if you zoomed in far enough with a microscope, what would “electricity” and electrons/stuff actually LOOK like? Tiny particles? Dancing miniature unicorns?

  65. Rachel Hendery says:

    What I’ve always wanted is a list of stuff I shouldn’t do. For example I come across advice like “never directly connect the positive terminal to the negative terminal of a battery” and “don’t solder a live circuit” and so on, but usually only after I already tried it :)

    Especially now I have an arduino, I’d love to know what stupid things I shouldn’t do because it could fry it.

  66. dinorossi says:

    i was recently working on a project involving electro active polymer (eap) material which required 5000 volts (yes, 5000), but only 100mA to be actuated. some people said it could kill someone if they touched the material while being actuated, while others said it wasn’t dangerous because the amperage was so low.

    i didn’t know who to believe, and didn’t want to find out the hard way.

    which is more dangerous for humans, volts, amps, or a combination of the two?

    (the project can be viewed here: http://www.caad-eap.blogspot.com/)

  67. Scott p says:

    I enjoy reading about various project and gave spent countless hours thinking about pulling the trigger on starting one. But where to begin? What equipment do I need and how to build confidence that it can be done? Maybe reading this book will help!

    I have questions about Basics like resistors, capacitors and what size etc

    Thanks

  68. daniman750 says:

    So I’m in the midsts of disassembling my electric fan (to build an automated catapult, in case you’re interested) and I noticed 3 wires leading from each of the power setting buttons (1,2,3) to the motor. I assume each wire is for a different current.
    I understand how current in the coil turns the motor, but how does varying the current change the speed of the motor? What is the relationship between the magnentic field of the coil and the rate of rotation?
    Thanks

  69. rekinom says:

    I was really disappointed to discover that EL wire was AC. What are the chances that someone will figure out how to make DC EL wire?

  70. gnilheb says:

    How to make electronics? That is the question that has always nagged at me.

  71. nashtr says:

    If we were wrong all those years about which way electrons really flow, then how have circuit designs worked?

    -TN

    PS: I can Google, I have a degree in Electronics Technology, and I know the answer. I’m just entering to win the book. :-)

  72. npkeith.myopenid.com says:

    What is a good resource for identifying components? I have a bench covered in salvaged and “grab bag” parts. Most I can identify at least at the basic level (resistor, cap, diode etc.) but some are a complete mystery. Most have some kind of ident code on them which I can google, but even that is not always helpful- sometime I get to many hits, sometimes I get none. A pictoral guide to components would be nice.

  73. marlenedegrood says:

    I’m a beginner in the world of capacitors, resistors, soldering etc. but the Arduino caught my attention several months ago and I began the process of learning to solder and understand basic electronics. I strayed away from it for a while but I’d like to get back into it if it’s really worth it for me … is the Arduino here to stay for a while? Thanks!

  74. jslice1001 says:

    I can read a schematic alright, so I thought that I would have an easy enough time getting things from the a pre-made parts list and putting them together. However, when I went to Jameco to look for the capacitors called for, my mind was blown there were so many different kinds! Differences in capacity were straight forward enough, but even with the same ratings there were tons of different ones made from different materials. And the kick in the pants was there weren’t any listed for the specific voltage called for in the schematics I had!

    My questions are, what’s are the different “styles” of capacitors all about? Is it just a size/shape thing? What do I do if I can’t find a capacitor that’s exactly right, are substitutions acceptable? How do I figure out what I should use?

    Thanks Make:!

  75. larryboy114 says:

    We all work with computers every day. I’ve seen the logic diagrams for full bit adders and the like. I understand how binary operations and computation works. What nags me is this: How did we get from “Oh look, electricity!” and “I have created a circuit that adds 2+2″ all the way to a Quad-core 3.0GHz processor? Who had the insight to look at simple electrical circuits and come up with the idea of computers? How did they envision things like a BIOS and microcontrollers and things like that from these resistors, capacitors and the like? I know it developed over time, but someone had to have that flash of insight the first time around. Who, and how?

  76. StayatHomeElectronics says:

    You are right in saying that there are many different types of capacitors. Deciding which type, electrolytic, ceramic, film, etc., is often dictated by whether or not they are made and what the cost of them is.

    Here are some basic generalizations:

    Large capacitance values are often made from electrolytic materials. Film and ceramic capacitors of any larger value tend to get really big really fast. Electrolytic capacitors can have relatively large capacitance value and still be of reasonable size.

    Ceramic capacitors go to much smaller capacitance values than electrolytics. They can also have very high voltage ratings and still be inexpensive.

    Film capacitors are often used for better high frequency responses. Certain ceramics also work well here. However, there is definitely an increase in cost for the performance.

    I think a good way to get a feel for the differences in the parts is to look for multiple parts with specific specifications, capacitance and voltage, and see what you can find. See if they are available in more than one type. Compare the costs of the parts. From there, the manufacturers also provide a lot of information on the benefits of one material over the others… Look up ceramic capacitors in both COG and NPO. NPO has better frequency response but will probably also cost more….

  77. AllenKll says:

    I am interesting in learning more about design. I have ohm’s law down, and understand what all the pieces do, It’s just that I was never told how/why they get put together in the configurations that they are.

  78. Phil says:

    (newbie question)

    I have a box of old electronics, from remotes to old computer components to old VCR’s. From the maker perspective, what’s worth keeping? Just the components like processor fans and motors or is it worth keeping the circuit boards to reuse their components, too?

    Thanks.

  79. bill says:

    In a recent interview “Steve Wozniak’s education in electronics was rather unconventional. He pointed out that, unlike his other school subjects in which he was merely required to memorize information for a test, his father taught him electronics in a way that allowed him to fully understand the information. Instead of just giving him a definition for “capacitor,” his father took him back to the very basics of electrons and energy and how these related to a capacitor, and how a capacitor related to other electronics concepts. Not only would young Steve feel that he fully understood what his father had taught him, but he was then able to actually go and do something with his knowledge. He stated that it was through this style of teaching and learning that allowed him to begin creating electronics projects at a very young age, and to eventually go on to create the computers that have indelibly left their mark on technology as we know it.”

    Reading through these comments I see a common thread of users (including myself) that get the definition of the components and what they do but are struggling with how the come together and how they are used and move beyond the individual components.

    So in what way did Steve’s Dad teach him electronics that allowed him to fully understand electronics?

  80. TuxBobble says:

    Some may be aware of the fact that different countries have decided differently about their standards in terms of power supply and distribution, etc. I am aware that there is a difference between AC (alternating current) and DC (direct current), but don’t know WHAT the difference is, and what the advantages/disadvantages of each are…

    1. HowTutorial says:

      The transformer is a very efficient way to step up or down a voltage, with a corresponding adjustment in current. But transformers only work on AC voltages.

      Ohm’s law can point out a problem with distributing electricity through resistive wires to everyone’s homes. All that current will be heating the power lines, and wasting energy.

      The transformer comes to the rescue. Power is what we want in our homes, and power is the product of voltage and current. If we use a step up transformer at the power plant, we get very high voltages, which need correspondingly smaller currents to transmit the same amount of power. The smaller currents means less wasted heat. Just use a step down transformer at the home.

      Here is the rest of the story:
      http://en.wikipedia.org/wiki/War_of_Currents

  81. MattMiddleton says:

    I’d like to know how people reverse-engineer electronic devices. I can figure out part of it (google + chip labels), but how do people understand what a device does by looking at the board/chips/wires/etc.?

  82. Tom Bierly says:

    I’ve been working in wood and metal for a long time. I want to start adding some electronic features to my projects. What should I learn first? Should I start by putting wires together or by learning the theory behind it?

  83. zthralls says:

    Recently I utilized magnet wire for a project for its smaller diameter and coating. I had three spools each with a different gauge. I ended up choosing the medium guage wire for fear of the smaller guage getting too hot and possibly burning the material touching it. I wanted to know is there a way to determine how much power can safely go through a wire size and the temperatures to expect when you vary the amount of power. A chart or graph would be most helpful. Thanks

  84. levrickards.wordpress.com says:

    I built a Hex Pummer about two years ago, by following the instructions and soldering where it told me to. But I don’t feel like I have any understanding of what I did.

    What’s a resistor? If electricity flows from a power source through the circuit like water flowing downstream, is a resistor some kind of skinny channel that reduces the amount of water that can move through… Or is it more like a reservoir, slowing the electricity down so it can fill up the pool before moving on downstream? Or what?

    And what’s the difference between a resistor and a capacitor. Various project instructions always talk about capacitors like reservoirs that soak up electricity, and then dump it ALL out when it gets full. Is a capacitor a kind of resistor? What’s actually happening inside there?

    1. levrickards.wordpress.com says:

      http://en.wikipedia.org/wiki/Electrical_resistance

      “The electrical resistance of an electrical element measures its opposition to the passage of an electric current; the inverse quantity is electrical conductance, measuring how easily electricity flows along a certain path. Discovered by Georg Ohm in 1827,[1] electrical resistance shares some conceptual parallels with the mechanical notion of friction.”

      That’s a great metaphor – that electrical resistance is conceptually similar to friction.

      What I still don’t understand is why we use resistors at certain places when designing a circuit. Is it just so we don’t blow out various components? Or is there a way that resistors allow us to control the flow of electricity through a circuit…?

  85. adamlee says:

    i know the basic equations ( well sort of, i have forgotten most of my schooling…) but i am always confused by the differentiation between power and voltage, i mean yes i understand time is involved in power, but what is time ! ? ! ?

  86. floatingbones.myopenid.com says:

    Why are the ignition systems for fluorescent bulbs so flaky? Why do some fixtures have a ballast box and some have a small electronic starter?

    We have little 24-inch fluorescent tubes in my bathroom. Those starters seem to be flaky by design: new bulbs often fail rapidly.

    Is there some way that fluorescent ignition systems could be made more robust without a significant increase in their expense?

  87. rbarrier says:

    My biggest question is what do the letters cc, dd, and ss that follow the capital V mean in schematics? I always see them and know VCC and VDD are refer to the positive connection of your power supply and VSS to the negative or ground but I have no idea what the pairs of letters stand for.

  88. typhune says:

    While trying to trace circuits, I still get hung up on the “flow” of electrons when measuring vs how to read a schematic. Is there an easier way to think about this?

  89. ppphhhh says:

    Which one is more lethal – high voltage or high current?

    1. npkeith.myopenid.com says:

      In the pure sense, high current is the more dangerous. To give an example – on a dry day, you scuff your feet on the carpet and touch a doorknob – ZAP! you feel (or even see) a little spark. That was thousands or even tens of thousands of volts – very high voltage, but very low current, possibly just a few millijoules of energy. Defibrillators deliver hundreds of joules, which is enough to stop and hopefully reset a heart.

      That being said, when you see a sign that says “DANGER, HIGH VOLTAGE” it most likely means both high voltage AND high current.

  90. theyallhateme says:

    I just got an Arduino and I love it. I’ve torn through all the tutorials I can find that use the parts I have. I’m scheming up my first project now, a RFID lock box.

    Is there a short list of what to never/always do? I feel like my experimentation is limited by my fear of melting my Arduino.

  91. MiltonDear says:

    When I turn on the fluorescent lamp in the bathroom, my speakers in the living room pop loudly. What gives? The speakers have a built in power converter and don’t draw any more current, so how come they make that noise? Also, I assume that whatever is effecting them is effecting anything else connected to the same main — should I be worried about the computer and lamps and whatnot, or is the charge small enough to be negligible?

  92. hekc says:

    I love gadgets, I want to make them, where do I start?

  93. ksouder says:

    Just was wondering how can manufacturers of modern computer chips place thousands of working, viable electrical components on spaces that in some cases are only 1/2″ square or even smaller?

    1. HowTutorial says:

      Very carefully. :-)

      Think of a complicated version of silkscreening, with stencils created using a complicated miniature photography. Add a very careful control of your build process with clean rooms to keep out dust bigger than what your building, very pure material ingredients, and very precise temperatures and times for your steps. Use computers to design and draw your stencils. Add metals and other atoms of interest with something called vacuum vapor deposition. Add a layer of glass to create multiple layers on top of each other. Remove parts of what you have added with acids to create holes to fill with metal and connect between layers. Make many chips in parallel, test them, and sell only the ones that work.

  94. Jeff Schumaker says:

    How do capacitors store a charge?

  95. EvilGenius121 says:

    Hey- can we comment on multiple questions as well as submit a question? I dont really care if both ways count, but i have a few answers for some questions presented here :)

    1. Gareth Branwyn says:

      you can comment on questions and ask questions. That’s fine.

      This is an awesome discussion. Thanks to all who’ve been taking the time to answer questions. When it’s over, I’ll repackage some of the Qs and As into a post here.

  96. skee57 says:

    If electrons travel from neg to positive and leds need a resistor to not be burned out by the current then why are the resistors not between the incoming electrons or the neg incoming current and the leds? They aren’t often enough. Is my perception too simplistic?

    Thanks

  97. 77x says:

    What is the air speed velocity of an unladen swallow?

    Oh.. has to be electronics related..

    Why doesn’t my multimeter work on LEDs? The meter shows OL when I’ve
    tried it in ohms, diode, and signal in both directions with working LEDs.

  98. alex says:

    Is it better to connect both ends of a shield jacket or leave one end floating in order to prevent ground loop current? Are ground loops overrated?

  99. PAS says:

    If you discharge a capacitor through a resistor and an LED, the voltage across the capacitor decreases asymptotically toward zero. The voltage across the LED, however, decreases toward a nonzero number. Why is this?

    (Full disclosure: I teach physics, and have my students use a circuit like this. I think I understand the reason…. I really just want to enter the drawing for the book!)

  100. https://me.yahoo.com/a/DrdeBjJ_lJrJXJR4ltUo5ZNwfO26V9U-#7d695 says:

    What is the best way to make a small electronics project run on AC power? Put a transfomer (inverter?) on-board or use a power adapter that has a tranformer built into it?

  101. dork.warrior says:

    When I was younger I wanted to know how Simon knew what to say and could remember his pattern so I “borrowed” some of my dad’s tools and in the back of my room behind my bed where I had my workspace and took it apart. Simon never said again.

    A few months ago I decided I wanted to get serious about electronics and making again. I rented a book on basic electronic from the library and got through the first chapter before having to return it. I learned what volts and amps were and that’s about it.

    My biggest question are about resistors, capacitors and the such. When do you use them? How do you use them? How do you hook them up? What’s their purpose (alien in nature?)? How do I get 20 led lights to be triggerd by a pressure switch?

    1. Steve Murphy says:

      Simon Says get an Arduino and get started! They can be found as cheap as $20. Look, if you can light an LED you can control the world. Get to that lit up LED as quickly as possible! There are some great arduino products at adafruit.com, sparkfun.com and right here in the maker store. There are free Arduino tutorials here: http://www.ladyada.net/learn/arduino/ that will be a great way to start.

  102. Chris Spurgeon says:

    I can connect a light bulb to the positive and negative terminals of a battery and the bulb lights up. So how come when I connect the light bulb to the positive terminal of one battery and the negative terminal of another battery the bulb doesn’t light up, even briefly? Is the chemical reaction in batteries REALLY so fast that the reaction detects the loss of electrons from one end of the battery without the immediate arrival of electrons at the other terminal?

  103. amcguire.myopenid.com says:

    Since high school I have always wondered if there was a way to get the smoke back into transistors. Throughout my engineering career I have released the smoke from hundreds of transistors and then they stop working. I have determined that it is the loss of smoke that caused these to be inoperable and wanted to know if there was a way to get the smoke back in. Any ideas?

    1. stubish says:

      Hi,
      I’m still an electronics beginner, but to the best of my knowledge and from seeing smoke escape from a few guitar amplifiers over my time, caps are powered by magic smoke. Once that magic smoke has escaped the caps will no longer operate. As far as I know, nobody has figured out how to get the smoke back into caps that it has escaped from.

      Maybe someone with more expertise can chime in?

    2. Chris Spurgeon says:

      I have the same problem. Happily the time machine I’ve constructed will take care of that problem…you’ll be able to slip back in time to just before you let the smoke out of your transistors and correct your mistake.

      Unfortunately, every time I fire up the time machine it burns out *my* transistors and I have to start over. So far I’ve been unable to figure out a way to build a time machine that I could then use to help me build a time machine.

      1. EvilGenius121 says:

        Im guessing you just fried them by exceeding their parameters or using them incorrectly, same as the caps. As for the time machine problem, i suggest using a campfire and some green leaves to help the transistors replenish their smoke supply.

  104. Old Age says:

    I started learning electronics over this past summer. Everything came pretty easily and I found myself building things constantly. The thing I disliked the most though, was using lead solder. I have always wondered why someone hasn’t developed a cleaner, safer alternative to lead solder. Yes, lead-free soldier is available, but it isn’t as effective as lead solder. Can anyone give me an explanation? Thanks!

  105. jcayer says:

    What is the best way to determine if a capacitor is
    A) still holding a charge, and B) still good?

    How would you discharge one if it was charged?

    1. EvilGenius121 says:

      There are multiple methods. One of the easiest is hooking up a resistor (the higher wattage rated, the better) or an led to the respective leads (be careful with an led, as it might fry) and seeing if it lights up. If it does, the cap was holding a charge. Leave it hooked on for a while to discharge it. Be EXTREMELY careful with large capacitors, as they can shock you pretty good (I know, i got shocked by a camera capacitor). As for charging them, i recommend hooking up a 5v (or close) power supply for a few secs, then using the discharge method. Never go above the voltage rating (usually labeled on the side of a cap). The quick and easy way to discharge large caps is putting a screwdriver across the leads, but this might damage your caps (and hurt you if you’re not careful and its not grounded). Tiny ceramic caps (the oarnge disc shaped ones) usually do not carry much of a charge, so an led might not light up when using them. Community, please correct me if i am wrong and/or missing info here :)

  106. rhino says:

    I was always wondering, if there is an easy way to learn how to read an complex circut. Any tips?

    1. KC_Bigman says:

      All I can offer is to try to break it down into manageable parts, say, power conditioning circuit, motor control, LCD control. Then break that down further. You can use crayons to draw boxes around the board to isolate the big picture items. If you are looking at a large schematic, do the same thing, break it down into its basic functions then ‘zoom’ in.

  107. KayDee says:

    I know very little about electronics but I would love to know more. My main question is how does a board do all the different things they seem to do? A vague question I know but that’s because I’m still very far from understanding how it all works.

    1. EvilGenius121 says:

      Usually a board consists of one or more IC’s (integrated circuits), and the components to make them run the way they are supposed to. Sometimes different components will make the circuit do different things, other times changing a components value renders a circuit inoperable. The most common electric component is the resistor, which limits the flow of electricity. Another common component is an LED (light emitting diode), which, when hooked up the right way, produces light. Your computer motherboard probably has at least a few dozen IC’s and probably a few hundred resistors. Other components help too, like a capacitor, which stores electricity. There are definitions for these parts all over the web, and MAKE has put together a few videos showing what some of them are. Here’s a link:

      http://blog.makezine.com/archive/2011/01/skill_set_understanding_electronic.html

      They actually posted an addition today showing how to use a multimeter. Here’s the link:
      http://blog.makezine.com/archive/2011/01/make_presents_the_multimeter.html

      And another one a few hours ago for understanding schematics :)

      Hope this helps and good luck with your endeavors!

  108. KC_Bigman says:

    I’m sure you know that there are multi-layer circuit boards, but did you know that some are 10′s of layers thick? I have worked on boards that were 42 layers thick.
    You probably also know that they have to make each layer separately, but did you know that they are not all made the exact same size? When the layers are pressed together the expand at different rates, so they are printed at different dimensions to account for this ‘stretch’.
    We used to have to make the board, then cut out coupons from the corners and measure which layer stretched to much and which one not enough, then put a factor into the printer to account for the stretch, then make another board until we got it right.
    I think it would be interesting for some people here to take a tour of a manuf that makes these large, multilayer boards.

    1. EvilGenius121 says:

      What were the boards primarily used for? Computer mobos, specialized equipment etc?

  109. Peter says:

    Ok, so I read that the electrons actually flow from the negative to the positive terminal. But the term “current” refers to a positive to negative terminal flow. So if I have say, an led, that I want to limit the amount of voltage going to it, should resistors be placed between the led and the negative terminal or between the led and the positive terminal? In my head I picture water flowing out of the negative terminal so I should think putting the resister there would have the effect of “slowing” that water stream. Right? :)

  110. Jeff says:

    Whats the best way to figure out capacitance on parts with no labels? I got a grab bag of capacitors from radio shack, and there is no writing on some of the capacitors.

    1. Jeff says:

      The title has nothing to do with the question… that is what I get for not hitting preview first!

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