synthgeek's blog

Here is my latest little standalone noisemaker:

This is a small 3-oscillator logic synth, based somewhat on the same concept as the TrigPulser module in Loid. Like the original TrigPulser, it is based on the CD4093 quad 2-input NAND Schmitt trigger. In this synth, one oscillator is turning a second oscillator on and off, and the second oscillator feeds one side of  a NAND, while a third independent oscillator feeds the other side.

Here’s the schematic:

The range of sounds it can make is pretty amazing- though it can do the beepy & droney stuff you might expect, it can also do much more (especially when controls are swept)- harsh static-like noise, vocal-like sounds, oscillator-sync type stuff, etc. Here’s a couple of demos- audio, then video:

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As I once again need more money for parts, this one is going on eBay- I do plan to build one for myself as well though.

This joystick (a “Flightstick Pro”) was another great second-hand shop find. Opening it up, I found three 100k pots (one for each joystick axis, and a throttle wheel):

My thoughts immediately turned to a 2-osc synth of some sort (each axis controlling one osc), and as I started brainstorming, the idea of a filter of some sort for the third pot came along. My final plan was for the oscillators to be supplied by a CD40106, which would feed two buffered squarewave oscillators into an AM circuit. I chose the TS12A4514 analog switch for the basis of this AM circuit, mostly due to space considerations. The filter is a passive highpass type, using a metal-film 100nF capacitor and the third pot. Each joystick axis also has an offset wheel, which can allow for setting the range of the associated osc, or just act as another frequency control.

Post-op inside photo:

The final product:

Here’s an audio demo:

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…and here’s a short video:

This one is also going on eBay to raise some money for parts. It’s probably the one I’ll have the hardest time parting with, of all the things I’ve built & sold so far. If I ever find another joystick like this, I’m keeping the next one.

I’ve decided to start selling these on ebay to raise some money for parts. Here’s a link to the current auction… and here’s a photo of the current model:

Here’s a revised schematic showing additions/changes, as well as a parts list:

I’m putting this one on ebay:

The sound-making portion is the same as the Coffee Can of Doom, but this one is housed in a VHS tape case instead of a coffee can.  Here’s a recording of me randomly messing with the contact points:

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