Building a Gigatron: Capacitors

Previous post: Buying a Gigatron

Enough parts have arrived to start building the Gigatron. The assembly guide suggests the build takes 3 or 4 hours. Given my lack of experience, I suspect it will take longer. (Possibly much longer.) The plan is to space out the build, doing 1 or 2 steps at a time. That will allow some time for reading at each step, learning a little about what I've just added to the Gigatron.

Onto step 1.

To practice with soldering, we start by soldering 40 ceramic 100nF capacitors, marked C5 through C44.

- Gigatron Assembly Guide, p. 30

40 ceramic capacitors, each with 2 pins, sounded like a lot of soldering but I definitely needed the practice.

On the PCB the capacitors are arranged in a roughly clockwise pattern, which is a tiny but lovely detail. The arrangement makes it easier to move from C5 to C6, for example, and be confident that none of the locations have been missed. Marcel van Kervinck and Walter Belgers clearly put a lot of care and thought into creating the Gigatron.

Soldering felt very slow at first. I was out of practice - and didn't have much in the first place - so everything felt unfamiliar. After a while it became oddly meditative. Half listening to something on the radio while soldering felt much more relaxing than half listening to music while coding.

Not having a good inside location for soldering, I've been doing it outside. There's an exterior power plug, so it's convenient, and the ventilation is good. The downside is the weather. After soldering about 20 capacitors, it started raining. Quickly grabbing things while getting rained on and trying to avoid a hot soldering iron wasn't fun.

After everything dried a bit, soldering resumed and I managed to finish the 40 capacitors. Some fiddling with the multimeter ensued as I worked out how to test for the "infinte resistance" the guide says the circuit should have at this point. It seems good and the soldering looks much better than my previous attempts, so hopefully it all works.

Before starting to solder, I'd wondered why on earth I was soldering 40 capacitors. Capacitors store energy and seem to be used in circuits for a bunch of different reasons. In the Gigatron, the capacitors are probably there to smooth out the power supply. If the voltage of the power supply drops briefly, capacitors can make up the difference and maintain the correct voltage. It sounds like integrated circuits (ICs), the little black chips that will go into the Gigatron, are sensitive to small changes in voltage, so the capacitors help protect the chips. Those 80 points of soldering to add the capacitors suddenly seem a lot more worthwhile.

A Gigatron printed circuit board with 40 ceramic capacitors soldered onto it.
The Gigatron with its 40 ceramic capacitors. Photographing the shiny PCB proved difficult.