Filter with LFO

I’ve been playing around with filters lately, especially the popular WSG resonant low-pass filter. It’s a really simple build and is ideal for putting a bit of warmth into the harsh square waves of my logic-based synths.

I did a quick experiment today, adding a home-brew vactrol to the cut-off pot, to make a junky LFO. Here’s a schematic, if you’re interested. You can hear it in this demo, where I’ve used the sinister tone generator as a source. There’s plenty more work to do on it yet but it’s pretty fun just as is.

LDR DAC Melody Generator

At the workshop last week a ten year old came up with a DAC design I’d never thought of before, which we turned into a really cool and simple melody generator. In the schematic you can see the first three clocks blink the LED’s on and off at different rates (try 4.7u caps and 1M pots). As the amount of light falling on the LDR changes in uniform steps, you can hear the pitch go up and down in a musical way. You could actually tune this to a musical scale if you tweaked the spacing of the LEDs, and put the whole thing in a black box away from ambient light.

Synthbot Exhibition now on!


My exhibition is now on at Deluxe Cafe for the next two weeks. Go in and have a play with some singing robots, or check it out online here.

Homemade Oscilloscope

You wouldn’t believe how easy it is to turn an old TV into an oscilloscope. Snip a couple of wires and switch them around, then add an input jack and you’re away. In the video I’m displaying the audio from the TV tuner, but you can plug in any source.

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Weltmeister Combo Bass

My pal Vic has given me her Weltmeister Combo Bass keytar to reinvigorate. There’s not a great deal of info online so I’ll collate what I know here in the hopes that it will be helpful to someone else in the future.

Weltmeister Combo Bass
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4-stage Gated Oscillator

The first project I’m teaching in my DIY synth course is a 4-stage gated oscillator. It takes a couple of hours to put together, costs about $30 in parts, and is a good starting point for absolute beginners. So what’s going on in there?


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