Oscilloscope Music

A few weeks back, I caught a video on AvE’s YouTube channel of graphics drawn on an oscilloscope, given an audio input. Last week, Ben, Garrick and I decided to give it a try at OMG.

According to Garrick’s research earlier that week, “older scopes” do better with this sort of thing, and OMG’s scope is plenty old. We had to do some tinkering with the settings, and the phase, eventually arriving with the left channel on Input 2, alternating vertical and External trigger (ch2). It worked best if the laptop volume was turned clear up, as it gave the best signal to noise ratio.

We’d initially hooked the scope directly to a laptop headphone jack (through a spaghetti of cables), but as Eric pointed out “To be music, there’s gotta be…music”, and no devices we had would play on the headphone jack AND the internal speakers at the same time.  We ended up hacking up a powered speaker to give us a stereo output and play both channels on a single speaker. This gives us something to feed the oscilloscope AND lets folks hear what the audio actually sounds like. In addition, it had a lot less noise than our initial mess of wires.

As for what we played, we just searched YouTube for “Oscilloscope Music”.  Someone who works with Jeff mentioned Aphex twins “windowlicker” and “songs about my cat” by Venetian Snares as two examples of spectrographic songs.

LiPo Battery Ruggedized Power Module

A while back, we decided that we needed a 24v power source for various “testing” applications. This source needed to be durable enough for daily use by a wide variety of people without becoming damaged. It also needed to protect the device being powered, and be easy to maintain.

Given that tall list, Ben suggested a HobbyKing LiPo pack, 6S, 5Ah. With that start, we decided that it should have volt and amp meters for monitoring, as well as a circuit breaker to provide positive power disconnect, and protect the battery (easily capable of 150A into a dead short).Meters were ordered from Ebay and the breaker was something out of an old UPS.

The blue enclosure is a waterproof storage box from Walmart, modified to pass through various connectors.  It’s not waterproof at this point, but we’re more after the durability of the polycarbonate than the waterproof aspect anyhow.

Internally, there’s quite a bit going on.  The battery is packed into a foamed-off area, while the other side contains the electronics, including the circuit breaker,ammeter shunt and all the connectors.

Charging is accomplished via a modified ATX connector (which re-presents the balance plug and main power leads), with a fuse to protect against abuse. The idea is that it’s virtually impossible to charge the battery improperly, or to break a relatively fragile balance connector.

Overall, it was a pretty straight-forward build, and cost around $90, including the battery and all the connectors.