Noisemakers and electronics at HacDC.

01 May 2009

Thursday nights at HacDC for the next couple of weeks have been taken up with a nifty new class courtesy of Elliot - a basic electronics course in the guise of building noisemakers. From basic oscillator theory we moved on to... I couldn't make it to the second class due to a scheduling conflict, truth be told, so I don't know what was taught. Jade and I did make it to the third class which was about low-pass filters (which allow low frequencies to pass (the definition of 'low' is highly situational) but filter out high frequencies), how to vary the dynamics of the circuits (we made heavy use of photocells but other attendees used potentiometers, or manually variable resistors, possibly to much better effect), to how to pull nifty tricks with them. The circuit that Elliot diagrammed on the whiteboard has a lot of uncertainty in it - you really have to play around with them to see what each variable will do to the sound. Depending on what you use and how you wire it, a given resistor might vary the volume, the pitch, the gain, or something else entirely. This was Jade's first time working with electronics but she picked up the basic principles very well and it took her less than a minute to become proficient at soldering. It took me a bit longer to figure out exactly what was going on (I really need to start teaching myself electronics, along with every other project I have on my plate). In hindsight, I think that photocells were perhaps not the best way to go due to how wiggy they can be to control when you've got a decent amount of ambient light. We wound up staying until 2330 EST5EDT last night playing with circuitry and watching the various sorts of zaniness going on, but had to leave for home around then because Jade had work in the morning and I had to get up early to go to the dentist and finish my latest root canal.

Under the cut, a few photographs taken at the 'space on Thursday night.

A small neon bulb. A glass of water. A microwave. Kind of cool, actually...

This is what Timball was doing with that hacksaw - cutting the body of a large-ish transistor open to see what it looked like inside. Surprisingly, the actual silicon is only a fraction of the size of the metal can it's packaged in.

I'm not entirely certain, but I think someone converted an incandescent lightbulb into an plasma globe and suspended it from the ceiling alongside the Japanese lantern.

The neatly organized dead-bugged circuit on the left is a very basic oscillator hooked to a single-chip amplifier built during the first class. The even simpler circuit on the right that was formed using non-rigid wire and looks like I patched it together with paper clips is a low-pass filter that was constructed on Thursday night. The idea is that the oscillator feeds its signal into the low-pass filter (by way of the jumpers), the low-pass filter lets only the low frequency sounds through, and the sounds come out of the second speaker. The photocells were supposed to vary the dynamics of the low-pass filter, but I didn't discover until later that a broken connection around the back of the amplifier (the tiny chip at the top left) caused my oscillator/noisemaker to work only intermittantly. Metal fatigue fail.