Got the 1222 tuner VCO for Christmas, just finished building it! One small problem

I’ve been wanting to build this for a while, i built the strip board version Without the tuner a couple months ago and it worked for a few days until I somehow broke it. Rather than ripping my hair out trying troubleshoot it, I asked my my mom for the kit as a Christmas present. It arrived a couple days ago and after a long night of soldering I successfully built it(with only one real issue).

I pretty much did everything by the book with a couple of small modifications. Instead of using euro rack style headers for power, I used a 5 pin molex adapted to 3 pin on the other end. I also used a different rotary switch than the one Sam used, I went with a different 12 pin single pole switch that looked more durable.

The main problem I’ve had is with the octave selector, the oscillators only make sound if the switch is in one position, when I turn it to a different position it stops working. If I poke one of the wires going to the switch(the one furthest from ground) it makes all sorts of glitchy noises. I assume that I wired the switch wrong, I’m not sure how though. The switch that I used doesn’t have markings for the pin numbers, I assumed that it didn’t really matter which pins I used but maybe that‘s not the case? I guess the other possibility would be bad solder on the precision resistors. Besides that, the “center” trim pot intermittently increases the pitch of the oscillator when contacting the screw driver, it works fine otherwise though and I was able to tune it easily.

All in all, this was a great project and I’m happy with the results. This was my first time building a module with a proper kit and it’s definitely less messy than working with stripboard and having loads of jumper wires running all over the place. I love the amount of detail Sam put into every surface of the PCB and panel, especially the message on the back side of the panel about stocking up on beans.

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What’s the rotary switch you used? You’re sure it’s single pole? It looks like it has too many pins for that.

If you have a datasheet for the switch it should tell you what connects to what. If you don’t, you can use continuity testing with a multimeter to figure it out. Assuming it doesn’t matter what pin you connect to is almost always a bad assumption. In fact assuming anything is usually a bad assumption.


what type of rotary switch did you get? I belive it should be a make before break varient. I screwed this up the first time and it gave me issues that are slightly similar to what your having where it only worked on a few settings…maybe a fluke idk

And check your soldering :slight_smile:

Good luck


whoops, i think we posted at exactly the same time haha


This is the switch I used, it’s advertised as 1 pole, 12 position. it’s my first time using one so without any markings I have no clue what the pinout actually is.

Yeah, I did some Googling but could not find a datasheet for that part.

But in the inner ring, is there only one contact that sticks upward as much as the ones in the outer ring? Can’t tell from your picture but that’s what I see in the Amazon link. That should be the contact for the common connection. Then if you turn the switch all the way to the left and check with your multimeter there should be continuity from that to one of the pins in the outer ring, that’s where one wire connects. Likewise if you turn it one, two, three, or four positions from there the common should connect to four other pins in the outer ring and your other wires connect there. Can’t tell if that switch provides a way to stop you turning past the fifth position, if not then maybe solder the remaining pins to the fifth one to avoid a floating connection.

Sam shows the wiring here:

He’s using a different switch but it’s the same idea.


Yeah, there is a common ground in the inner ring, I have that wired to gnd. The switch doesn’t have a stop in it so there’s no way to turn it all the way to the left. I’m Not sure if I’m following what you’re saying 100% but I tested for continuity between Ground and each pin while turning the knob and there is continuity between each one, are you saying that pin1 goes to 5v and should be clockwise of pin 2? Here’s a closeup of how I have it ATM, my solder joints are a bit rough I know lol.

I just rewatched the video and realized that I connected the center pin to the opposite side that Sam did. I got thrown off by the letters GND next to it, I guess the center pin goes on the arrow side instead! Hopefully that’ll fix it.

Edit: Yep, that solved my problem, you’re a lifesaver! It seems like I should solder the other pins to 5 like you said, unless there’s a simple way to put a stop in the switch which would be an ideal solution.