Short-Term Plans and Problems

A project log for The Diode Clock

A digital clock built with Diode-Diode Logic (DDL), a quirky new logic family using only common diodes and passive components.

ted-yapoTed Yapo 05/13/2016 at 03:390 Comments

Just a quick update to get me familiar with project logs on, and into the habit of sharing.


I added a bunch of PDF documentation to the project today. I had it lying around, and figured between the various documents, you could get a good idea of how this project works:

Wiring the Clock

It wasn't as fun as it looks...well, OK, it was :)

Two Problems

Open Documentation Source

I have two problems at the moment. First, in the spirit of open-source, I am willing to release the source code for the above linked PDF documentation under an open-source license if anyone is interested. It's nightmarish latex and xfig and gnuplot, but hey, some people actually like that kind of drudgery. Let's leave it at that - if anyone wants to create a derived work from that documentation, let me know, and I'll release it. I am going to release the board design files, though, even if nobody asks ;) This brings me to the second problem.

Inductor Sourcing

After I made my first prototype DDL gate, I looked around for suitable inductors, which were shaping up to be the most expensive part of the design. I found a great deal on super-miniature 47uH formed-lead chokes (Taiyo Yuden LAL02VD470K) on ebay, and bought all the seller had, because they were very cheap, and I had dreams of building a full computer with DDL. They were so cheap because they were discontinued: I believe I have world's remaining supply - five boxes of 2,000, minus the 500 or so I've used.

So, here's the problem. Nobody seems to make through-hole inductors in this size any more, so if you use the PCB designs as-is, you can't buy inductors that fit easily. If anyone wants to build DDL boards, I think there are three options:

  1. Re-design the boards to accept larger through-hole (or SMD) inductors which are readily available. The boards are tight, but it might be possible.
  2. Use the existing PCB design with larger inductors mounted vertically on the boards. Clearance to next boards in a "stack" might be an issue.
  3. Ask me for some of my inductor stash, and we'll work something out

In any case, I'll be working on releasing the design files in the next week or so.

Next Steps

I'll be releasing the design files for the various boards, including:

The plan is to document and release things in roughly this order:

  1. DDL Demo Board
  2. DDL01 Hex NOR
  3. DDL03 Hexadecimal to 7-Segment ROM
  4. Simple DDL circuits to experiment with
  5. DDL02 "Chainsaw" Power Supply
  6. DDL04 "Whisper" Spread Spectrum Exciter
  7. TCXO Timebase and diode-only oscillator timebase experiments

Zed Naught Laboratories

If you look closely at some of the design files, you'll see my company, Zed Naught Laboratories, LLC, and the alternate domain Don't worry, I'm not trying to sell you anything. It's not that kind of company.