Silent Q

Azog's little slice of the world. Whee.

Transistor clock

Posted By on June 18, 2008

Somewhere along the line, I ran into a link for a transistor clock kit. When I checked it out, it was a clock built out of 100% discrete components. Nothing but diodes and transistors (and passive components). It looked pretty cool, so I ordered it up.

While I was waiting for delivery, I read thru the instruction manual, so that I knew what to expect. The manual gives full schematics, logic diagrams, theory and just about everything else you need to troubleshoot.

Looking at the completed pictures and reading the manuals is an intellectual exercise. When you open the kit, and start staring down over 500 diodes, almost 200 transistors, and probably about 500 resistors and capacitors, as well as other sundries parts, reality sets in.

The bare board:

One of the interesting things about the kit is that there are really only about 5 major components you’ll use. Mostly 10k or 100k resistors, PNP and NPNs and general switching diodes. Rather than printing component numbers on the circuit board (Q1, R1), the kit developer uses a novel symbol diagram printed on the board. So a 10k resistor is an unfilled rectangle, diodes are rectangles with polarity markings, and so forth.

This is an image of one of the component bags next to the symbol decoder in the manual.

And this is a close-up of the silk-screening on the board itself, showing you the matching symbols.

The kit includes solder braid, if you need to de-solder an incorrectly placed component. You’ll also get a cubic buttload of solder. It’s amazing how much solder you will go thru. As long as you’re judicious with solder, and don’t need to desolder (many) components, you’ll have an ample amount to finish.

Depending on what troubles you might run in to, you might even have a few bouts of digital troubleshooting. If you have an oscilloscope, that will of big help if you need to diagnose.

I did have a few odd problems, and the kit supplier was fairly communicative in working things out with me. I’m hesitant to mention the problems I had, because they were neither design flaws nor construction issues. Just one of those inexplicable circumstances, a bizarre occurrence.

This is a massive kit, but it is fun to build. I like things like this. You’ll either hone, or learn to develop your soldering skills, visual inspection, and least of all, patience.

Finished and mounted:

The above is without flash, since the flash overloads the readout of the LEDs. This is with the flash:

I did learn a few things:

  1. Make sure you have a sharp pair of wire snips. Mine were really dull, and rather than snipping the leads, I was mostly sawing at them. I had to order a new pair of standard green-handled Xcelite snips.
  2. After stuffing, when bending the leads for stability (when you flip it over to solder), bend the leads inwards rather than outwards. More often than not, you’ll be soldering close to other solder joints, and if they’re pointing inwards, you have less chance of bridging, and it’ll make snipping easier.
  3. If you do need to go back to re-solder cold or otherwise bad solder joints, I suggest you learn to use liquid solder flux. It’s messy and cleanup is a pain, but I never re-solder a dry joint.
  4. Take your time, learn to pace yourself, and take breaks. There is no race, and the goal is accuracy and neatness, not speed. Any time I tried to speed the process, I ended up with components which weren’t laying flush, poor solder joints, or things like that


3 Responses to “Transistor clock”

  1. Proxy says:

    Thx for your helpful entry

  2. Ralph Eitner says:

    hi at all,
    I am interested in the bare board of the transistorclock. i didn’t find any location to ask for on the webside of kabtronics. there were no guestbook or anything. please help me :-]
    greets from germany – ralph

  3. azog says:

    Hi Ralph, while I can’t comment on the availability of the bare board, there’s a “contact us” on the page at the top

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