Tuesday, November 13, 2012

It's Alive!!

Yes, back to electronics for a moment.

I decided to test the individual parts of the synth, together. So far I've just been building and testing each part (I've been referring to them as 'modules'), using my microKORG or guitar as a sound source if needed.

First I tested the oscillator and filter, which was difficult because they use different power supplies. I had to build a bipolar power supply just for the filter on a small corner of my breadboard. Talk about compact. But, they worked together beautifully!

I then built the distortion module between the filter. After adjusting the output capacitor and making sure wires were tight, I ran it again, oscillator>distortion>filter. Well, the filter worked, and the oscillator worked, but the distortion seemed to have problems. Adjusting the gain did nothing, and I couldn't use the diode clipper because it actually ended up grounding most of the signal. Go figure.

All this time, I was using but a single 9v Duracell. After having all that load on it, it's still measuring 9v. Go Duracell! Only power problem I had, aside from having to build a tiny bipolar supply, was when I swapped capacitors in the distortion module to a 10n (which, module by itself, makes for a neat highpass distortion), the oscillator acted as it does when you remove the power: a slow slew down in both pitch and volume. I didn't measure, but I assume the 10n cap introduced such a load that the battery temporarily died.

I had an idea for a highpass filter: a simple potentiometer crossfader fading between the clean signal and a moderately small (nF range) capacitor. It's not a true adjustable highpass, but it seems like it would create a seemingly highpass effect, at least to me in theory. Of course, I could always try to figure out how to make an RC highpass work.

Talking about that, if you look up an RC highpass, you'll see that you just have a signal input going into a cap, then out. There is a grounded resistor as well, but in my experience, if you make that a potentiometer, it doesn't sweep, but in fact at a certain point the signal drops out. Otherwise, it just uses the cap's capacitance as a filter. Annoying.

So yeah, that was my evening. Night, really, since I started around 3 hours ago at 10pm.

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