Ode to a diode

Ode to a diode

This Instructable throws down the gauntlet on TOD (Tons of Diodes) projects:

A new series of instructables that will be using tons and tons of diodes. No ICs are allowed, the only semi conductors are diodes and transistors. The only passive components allowed are capacitors, resistors, switches, inductors, and potentiometers (variable resistors for those who don’t know). Another rule is it must have more diodes then any other component. I made this all up, and I made up this group to see how creative people can be with electronics without resorting to ICs. My next one (this one is just a little wimpy intro) might use up to 2000 diodes.

Aw… snap! I’m going to do a project with 4,000 diodes!

TOD: Diode Matrix ROM intro (7-segment display) – Link

12 thoughts on “Ode to a diode

  1. guyfrom7up says:

    wow, I’m on make within an hour, this has filled me with soo much joy.

    Oh and I swear if the oracle comes around and bursts my bubble…

  2. The Oracle says:

    That’s an interesting idea. Of course you can do just about anything this way you can with ICs.

    But…the way you should be using the diodes and transistors is not “shorting things out”. That’s just wrong. It is not at all the way the “real” chips do it.

    I once built something very similar to what you have here except mine took 4-bit binary input and gave the full hexidecimal output. I also allowed myself 7400 series logic chips (my restriction was no programmable chips).

    If you do it properly (like a real LED driver chip would do it), or at least using proper electronics principles, this can be a great project idea, and very educational. If you’re just shorting out LEDs with diodes…well it’s your time to waste.

    BTW, if you do this the “right”, you’ll find those k-maps I referred to earlier very useful in setting up.

    And if you call that breadboard full…well don’t be so sloppy. All 23 diodes on a board that size wouldn’t be very full.

  3. Ron says:

    I hope David Cook is in the running for this one:


  4. guyfrom7up says:

    the oracle: I’m glad you were more polite this time. This is actually how Diode matrix roms work, the short is a controlled short, using a resistor to control the current. Real led driver chips use transistors, and I was trying to see how much I could do without transistors. Right now I’m designing an adding machine that uses no transistors, only leds for a display, resistors to control current, buttons for input, and diodes for logic.

    my board was full, 23 diodes, that’s 46 leads
    8 dip switch, thats 16 leads
    led display, thats 10 leads
    adding all up that’d be 72 leads.

    my breadboard has 230 points, + power strips, which were used for power and ground.
    230 minus 72 = 158
    minus one side of the dip all for ground
    158 – 40 = 118
    minus 2 rows for the display ground
    118 – 10 = 108
    minus the resistor space
    108 – 7 = 101.

    I have 101 holes open, that may seam like a lot, but remember, on the dipswitch and the display I only have 4 holes on each row to work with, and there’s a lot more leds for each one than four.

    Plus when I get more diodes on stuff begins to short. I can’t make the leads shorter because there’s holes under it which needs more diodes.

  5. guyfrom7up says:

    ok oracle, I’m sorry for everything bad, can we just stop arguing? I appreciate your constructive critism, I’d appreciate it even more without the insults.

  6. garyfixler says:

    The Coleco paddle was all diodes. I made a Flash version of one I got off of Ebay. I was going to do a bit more with it, but shiny objects distracted me:


    You can play with the full paddle on the right. Click all of its buttons, and click+drag the control stick around to see which pathways light up. It’s a pretty ingenious design, and I love those old hand-drawn ’80s traces.

Comments are closed.

Discuss this article with the rest of the community on our Discord server!

Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. His free weekly-ish maker tips newsletter can be found at garstipsandtools.com.

View more articles by Gareth Branwyn


Maker Faire Bay Area 2023 - Mare Island, CA

Escape to an island of imagination + innovation as Maker Faire Bay Area returns for its 15th iteration!

Buy Tickets today! SAVE 15% and lock-in your preferred date(s).