MAKE: Noise — Discuss this article

Showing messages 1 through 13 of 13.

• PICAXE-08 = the new 555 !
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  Although I'm very enthusiastic about Make:,the 555 article rather hacked back to another era! Come on guys-the 555 was introduced in 1973 for heavens sake. It may have been the most popular IC of all time,BUT 34 years in electronics is akin to an ice age in history.
  
  I went on record ~2002 as promoting a UK sourced PICAXE microcontroller as the new era 555 in fact. Cheap (~US$3),powerful,versatile, brilliantly supported & so easy to use that even your dog could understand their high level commands. There are now 11 in the Picaxe family,& all program via a free editor & just 2 resistors!
  
  OK- twist my arm- I'll look to pen a PICAXE Make: article,but suggest the curious see http://www.picaxe.orcon.net.nz or just Google.

  Posted by manukanz on July 04, 2007 at 16:19:36 Pacific Time

• PICAXE-08 = the new 555 !
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  I'm familiar with PICAXE (yes, I visited your site) but MAKE has already run a series on programmable microcontrollers. Surely you would agree that understanding the role that resistors and capacitors play in measuring time intervals is fundamental in electronics? What better way to learn this than with a 555. Yes, it can now be considered primitive, but it is a first step; and if I were teaching assembly language, I might start with an 8088 chip.

  Posted by charlesplatt on July 04, 2007 at 16:26:24 Pacific Time

• PICAXE-08 = the new 555 !
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  Yes-but at the time I'd pondered the Make: #4 micro article as being "too daunting" for newbies. You can have a Picaxe-08(M) version all setup for ~US$20 & be flashing LEDs & making sounds in minutes!

  Posted by manukanz on July 04, 2007 at 17:20:48 Pacific Time

• PICAXE-08 = the new 555 !
  Reply
  
  I certainly agree on RC combos,but the timing & duty cycle formula they follow on a 555 involves high school level algebra that's often a pain in the neck for newbies.
  
  
  f = 1.44/(R1 + 2R2) x C
  
  In contrast both R & C timing action can be readily shown via a PICAXE so that even pre-teens can understand!
  
  Most kids will be 13-15yo. before they can substitute values or rearrange) the classic 555 formula. I've even had first year tertiary students fumble over it...
  

  Posted by manukanz on July 04, 2007 at 16:53:11 Pacific Time

• 
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  I am trying to get back into making this stuff, and I figured since I haven't done it in years this would be a good place to start.
  
  But for the life of me I cannot find any 600 Ohm resistors, was it a misprint and you meant 680?

  Posted by kmarriner on June 26, 2007 at 17:10:07 Pacific Time

• 
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  The value can be plus or minus 100 ohms, so, 680 will be fine.

  Posted by charlesplatt on June 26, 2007 at 20:15:29 Pacific Time

• 555 timer
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  I'm wondering what I use for a power source in this circuit. (This is the first electronics experiment I've ever done so be nice!) Do I have to buy some huge DC power box?

  Posted by magician322 on June 22, 2007 at 17:00:08 Pacific Time

• 555 timer
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  The value can be plus or minus 100 ohms, so, 680 will be fine.

  Posted by charlesplatt on June 26, 2007 at 20:14:44 Pacific Time

• 555 timer
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  Oops. Sometimes I forget to mention the most basic things because they are . . . basic! I apologize for not specifying the power supply.
  
  You can use a 9v battery. Or you can put four AA cells, or four C cells, or four D cells in an appropriate battery carrier, to add up to 6v. Or you can buy an AC adapter (little black plastic box that plugs into the wall) capable of delivering anywhere from 6v to 12v DC at, say, 500 mA (or more).
  
  The 555 is very tolerant and will be happy with any of these combinations. If you start adding other types of chips, then you will need to control the power more appropriately.
  
  Just remember to get the + and - the right way around.

  Posted by charlesplatt on June 22, 2007 at 17:31:29 Pacific Time

• 555 timer
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  Thanks! I appreciate the response, and I'm impressed how quickly you responded.

  Posted by magician322 on June 22, 2007 at 17:49:04 Pacific Time

• Voodoo
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  Overall I liked this article (and the other articles by the same author), but the explanation of R3 and C2 in Figure 2 is very frustrating to me. Almost every electronics tutorial I've seen that's above the most basic level seems to have these mystery components that are never really explained.
  
  I have 3 questions:
  
  1. When designing this circuit, how does one know that the LED is susceptible to excessive current?
  
  2. When designing this circuit, how does one know that the 555 timer is susceptible to random noise?
  
  3. Once one has determined that the 555 timer is susceptible to random noise, how does one determine how to correct this?
  
  Once again, I liked this article overall, but I really wish components weren't just glossed over. It's hard for me to have any confidence when designing my own circuits if I can't even completely understand the circuits I'm learning from.

  Posted by clgonsal on June 03, 2007 at 19:09:24 Pacific Time

• Voodoo
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  "1. When designing this circuit, how does one know that the LED is susceptible to excessive current?"
  
  LEDs have a relatively low internal resistance. This means they will always try to suck more current than is good for them. To restrict their appetite you place a resistor in series, and the resistor often is 500 to 1000 ohms. You look at the manufacturer's spec sheet for the maximum forward current that the LED can stand, and either calculate a series resistance or use trial and error: put various resistors in series (starting with a high resistance and working gradually downward) and measure the current with a meter (also in series).
  
  "2. When designing this circuit, how does one know that the 555 timer is susceptible to random noise?"
  
  Almost all chips are susceptible to "noise" in a circuit, meaning random fluctuations that may be caused by (for instance) switching something on or off elsewhere in the circuit. By placing a small capacitor between ground and the pin recommended by the manufacturer, you guard against this problem. The capacitor absorbs the fluctuation. If you have seen 555 circuits missing C2, this is simply because many people just don't bother with it. I prefer to follow manufacturer specifications.
  
  "3. Once one has determined that the 555 timer is susceptible to random noise, how does one determine how to correct this?" The chip is always susceptible and should always be protected.
  

  Posted by charlesplatt on June 03, 2007 at 21:41:58 Pacific Time

• Thanks!
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  This is very helpful!

  Posted by clgonsal on June 05, 2007 at 08:55:57 Pacific Time