Phase 1 – Planning

Before coming up with a design for my circuit, I thought about what I want it to include. Ideally I’d like to have four gated oscillators, two of which can be controlled by either a fader or a photoresistor, a third by a potentiometer, and a fourth controlled by a textile interface or potentiometer.

A rough sketch is below along with a draft PCB layout.

List of materials needed.

• PCB board(s)
• Plastic enclosure
• Slide potentiometers (10K, 50K)
• Fader caps
• Knobs
• Switches
• On/Off switch

I started playing around with different values of variable resistors and capacitors.

Here is a schematic and sample audio file of one circuit.

Here is a second circuit and sample recording where I changed up some of the values.

Phase 2 – Breadboard to Protoboard

A lot of my parts arrived a little later so I’ve finally just been able to start testing the faders and moving to a protoboard.

I was able to figure out the pinout of the fader through some trial and error.

So far, I’ve solder leads onto the three pins of the fader once I figured out the correct wiring, and I attached some heat-shrink over the joints to make sure nothing ever shorts.

I have also soldered on the dip sockets for the 4093 chip.

I am still messing around with different values of potentiometers and capacitors. The two faders I have are both 50K. Previously, I was using other value of pots in place of the faders, so now I am having to adjust cap values so find a sound I like.

Update: As of 11/21/21

Everything on the breadboard.

I have soldered all of my components (2 faders, 4 switches, 2 pots, 2 photoresistors) ready to be mounted onto the PCB.

Unfortunately, I broke my skinny soldering tip, and had to use a larger one, which made it a little challenging to solder on the PCB. But it went alright, and I made sure to take my multimeter and check for any wrong connections.

It’s hard keeping track of all the solder joints and what’s what and where things need to go, and when going over all of the connections, I came across a few things I missed which became an issue when powering it up, luckily it wasn’t too bad of a problem.

I had some issues with the IC and its connection – I have a weird dip-socket that I had purchased from Adafruit for a previous PComp project, and while it works with other things like an Arduino, the short legs of the 4093 chip are a little shorter so it doesn’t feel like it sits properly. I meant to go to the IDM floor and grab one of the dip-sockets from the drawer – while I could’ve gone sooner, I meant to go on Thursday but caught a stupid cold and spent the weekend not allowed on campus until my Covid results came back. So instead, I had to figure something else out, and I ended up soldering header pins onto the chip, so that it would seat better into the dip-socket. Miraculously it worked … I think.

Before I worked on mounting everything into the enclosure, I wanted to test the circuit.

It didn’t work.

I kept checking and rechecking all of the connections and found that one of the capacitors was connected to the wrong pin of the chip. After fixing that, it worked! Mostly.

While the circuit works as I had intended it, it does not sound like it did when on the breadboard. It’s very crunchy and crackly. I’m really not quite sure what the issue is, it must be a connection, or a bad solder joint, but I was unable to figure it out. After troubleshooting for a while, I was just satisfied it made sound. And while it doesn’t sound how I would have hoped, it still makes some pretty gnarly noises.

Another thing I’d like to point out are the faders. They’re a little spotty, and seem to only work about half the length of the slide. I want to say it’s due to them being cheap, but it could possibly be a connection issue or something else.

When building out the enclosure, I rand into some difficulty making the cuts for the fader, and while there is a MUCH better / easier / efficient way, I was at home making this and had to use what I had. Honestly, it turned out pretty decent considering how I did it, but with that being said there are spots where the fader gets a little caught. But not too shabby for a drill and a knife! I did break a drill bit.

Final walkthrough and demo — film it while it works before it doesn’t — I talk a bunch and sound extremely nasally. Just skip through the video.