On the right is the pot that controls the "drive" amount. On the left, master volume control pot.

There's a button on the middle that somehow controls the state of the distortion (on/off)

My questions are twofold:

Can I inject line level audio somewhere in this circuit? Mix it via resistor into the signal coming from pin 1 of the TL072 before it hits the second pin from the top of that distortion amount pot?

Can I safely add a diode in parallel with one of the LEDs for a more asymmetrical clip without throwing the rest of the circuit way out of whack?

https://preview.redd.it/2oampzzdkiyd1.jpg?width=2048&format=pjpg&auto=webp&s=827d3bb5333cf6175423a5e1d023b04aa824858b

Has anyone come across these parts sold somewhere?
Also how do they work?
Looks like it's a digi pot under the hood and then the caps are magnetically attached but what kind of input does the digi pot accept?

Hello,
I tried my hands on designing a wave folder, something I havent yet tackled. Here is the finished schematic:

https://preview.redd.it/iek030tn7iyd1.png?width=937&format=png&auto=webp&s=fa1a7f3a28c92b9a66deb31cdb0618648fdc8e62

Instead of using the one-transistor wave folder method that most people go for, I decided to look at wavefolding mathematically and realizing it with opamps. A nice bonus of designing circuits like these is that the circuit mostly ends up being usable for many things (here its a wavefolder and a voltage controllable clamping circuit, which can also be seen as a VCA (kinda), instead of just a single use like with the transistor method.

A bit of theory:
The point between the two diodes (called CAP) limit the Input voltage to +/- CV. So for a +-5V input signal and a CV of 3V, cap will be 3V (plus the diode drop but lets ignore that).

https://preview.redd.it/9r7fbhig7iyd1.png?width=719&format=png&auto=webp&s=feab09a484c2b2c139e8feb689133923422800b7

Now for the opamp subtractor I will skip a bit of math but the formula for a perfect wavefolder would be

OUT = IN - 2*CAP

Oof. I would need to invert the CAP signal AND scale it by 2 and THEN I would need the subtractor circuit to get the difference. Let's not to that and be a bit smarter. If we divide by 2 we get OUT/2 = IN/2 - CAP. This way we only need to divide IN by 2 with a resitor divider and subtract CAP (as it is, no need to amplify) from it. This is done with the last opamp stage that gives OUT.

Now, OUT/2 of course only gives half the amplitude, this is compensated a bit by the 150k feedback resistor at the subtractor.

When CV is above the maximum amplitude of IN, with CV = max(IN)
CAP = IN and with OUT = IN/2-CAP = IN/2-IN = -IN/2 we get half the input signal inverted. Its a bit more becauseof the feedback resistor.

When CV = 0 we get CAP = 0. OUT = IN/2 - CAP = IN/2

Thus OUT = IN/2.

Oh look! With CV being either max(IN) or 0V, we can invert the IN signal. So we could switch the polarity with a square wave for example.

What do you think? :)

Hello everyone!

I'm looking for a desktop Noise or preferrably Glitch Box schematic. So far I've only found already built glitchboxes or DIY kits with custom PCB for sale but I would like top buy it from scratch. Does anyone have any schematic or component layover to follow?

Thanks for reading!

Anyone know how to exactly export their own customs samples to be used in hagiwo’s sample drums? I completely understand making audio into a RAW file, but it’s converting it into array data In PROGMEM format that I don’t really understand. I know he provided a link in his page for PROGMEN Sakuzo-San but I don’t know what that is exactly or how to use it. Any help?

So I've got an LFO that I made, and I don't even remember where I got the clock sync algorithm from. It worked okay with an lfo with a 16-bit phase accumulator, and even better with a 32-bit one, but it inevitably goes out of phase due to the lack of any dedicated phase correction.

The formula in my non-math-literate pseudomath:

sec_in_us = 1000000

bit_width = 32

update_rate_hz = 1000

((sec_in_us / period_between_clock_ticks) << bit_width) / update_rate_hz

Essentially, this makes it so that if you got exactly 1 << 32 then one cycle takes a second.

With this, I'm wondering how I can do what the title says and keep this thing in sync. I think that if I subtract the result * update_rate_hz from the ((sec_in_us / period_between_clock_ticks) << bit_width), I'll get the 'error', but I don't know what to do after that.

I'm open to other means of doing the clock sync if the method I've given above is completely alien. If anyone's got any suggestions at all, I'm happy to hear! Thanks!

Truly just need help understanding what parts needed and such along with basic understanding of how to piece it together if I did. Really want to get into this as a hobby.

I want to use the Raspberry Pi Pico for its USB host capabilities and want to power any USB device connected to it. I will use it for receiving MIDI signals from the USB device. The MIDI will then be sent over serial to a Teensy 4.1.

The Teensy 4.1 will also use its own USB host header, so the whole circuit will have two USB host ports.

I want to power both the Pico and the Teensy with external 5V, to begin with using a bench power supply but then probably via USB-C PD.

My questions about this:

1. How would I wire the power? Is it 5V to the VBUS pin of the Pico and 5V pin of the Teensy, with the solder pad for USB 5V cut on the back to prevent power both from the computer and the power supply?
2. Are there similar precautions for the Pico, as with cutting the 5V on Teensy?
3. How would I go about still being able to program the Pico (i. e. connect it to a computer and upload code) if the USB port would be set to USB host? Would it still be able to receive programming?

Hi,

I am working on a setup where I need to achieve an 8kV voltage supply to drive HASEL actuators (a novel actuator). Currently, I only have access to two bipolar high-voltage generators (shown as picture), each capable of outputting ±5kV. They have two terminals: one high voltage output terminal and one high voltage return terminal. I am considering connecting these in series to reach the required 8kV.

I have connected the two HV generators in series, where the ground (real ground) terminals of both generators are shorted. One generator outputs +4kV, and the other outputs -4kV, giving a total of 8kV across their outputs. However, I have a critical issue: this configuration doesn’t allow me to use both ground terminals effectively. Grounding is crucial in my setup because the HASEL actuators tend to retain residual charges after operation, and an accessible ground path would allow for efficient charge dissipation.

I attempted a connection similar to batteries in series, where the output terminal of one generator was connected to the ground terminal of the second generator. Unfortunately, this setup didn’t yield the expected higher voltage.

If anyone has experience with series connections of high-voltage generators or knows of a way to achieve an 8kV output while also making use of the generators' ground terminals for charge dissipation, I would be extremely grateful for your insights!

Thank you in advance!

hello everyone :)

i am about to write my thesis about a topic along the lines of DIY-synths (also: tinkering, maker education, circuit bending etc.)

for this i want to conduct interviews with experts in the field

so far i have identified several people with larger youtube-channels and other projects

to bring more diversity into my research i am now looking for female or nonbinary people for my interviews which are experts in the field

do you happen to be such a person or perhaps could recommend one? (be it via youtube or other portals)

thanks a lot and have a great day!

edit: wow, i woke up to all your lovely responses today - thank you so much! :)

HI Can anyone advise what resistor value this looks like and the capacitor?

I don't have a schematic so am literally going off a still from a video thanks

https://preview.redd.it/94q0dce015yd1.png?width=628&format=png&auto=webp&s=2589c8911c04b42d768dd562e77644289e1ce42a

Hello! Basically I want to convert old gutted 3.5 octave 41 keyboard that has a reed switch per key into a standalone synthesizer (It's a Formanta Mini soviet keytar, stylish as hell and keyboard feels nice to play)

I am not very experienced with any microcontrollers though...

In search of arduino projects of digital synthesizers that use the abundance of mega's inputs to connect one key per input and use other pins for parameter control and whatnot.

Or is it maybe simpler to fit two modules inside, one mega module with keys and pots as a midi controller (may need help finding such projects) and another one as some one of the many MIDI controlled arduino synthesizers? With optional benefit of midi output

Hi folks,

I've been working on a little DIY synth board. As you can see below, U6/U7 are very large chips, MIDI optoisolators for the two TRS MIDI inputs above. The spec sheet is here, they are Lite-On 6N137S-TA1-L. The schematic is also below (or in GitHub).

Can anyone suggest a physically much smaller opto-isolator for MIDI input please? This is just a test board, so a big one is fine, but I'd like to eventually make this board smaller and with 5 MIDI inputs (and outputs). If the suggestion is not compatible at the schematic level, I would appreciate an example schematic.

Thanks!!

Board 3D view from front

MIDI input opto-isolator circuit

I am trying to reverse engineer the MFOS Eight Stage Phase Shifter however I am struggling to understand how the phaser stage works.

this is what one stage looks like

I assume it is some sort of all pass filter however I can't find anywhere else which has this configuration with the C22 feeding back into the input. Also there is no buffer stage after each ota which is used in the configuration where an ota is used with an opamp like this:

the allpass that I am used to. I assumed that R would be replaced with the ota

Would anyone be able to explain how this works? Thanks

How complicated would it be and what would be the method for porting Ableton Link for Arduino? I’ve seen that the Torso developer created a library for the ESP32, but that seems to have been taken down from Github now for unclear reasons.

Here’s the link to the Ableton Link repo: https://github.com/Ableton/link

Other threads that might be of help for understanding the feasibility:

https://github.com/Ableton/link/pull/68 https://github.com/Ableton/link/issues/87

You've probably seen these cheap handhelds that can emulate most things from an Atari to a PS2 depending on how nice the chipset is. I recently got one and set it up as a frontend for a "headless" Dirtywave M8, this is relatively easy to do since you can sideload programs and most of these handhelds have USB OTG for either wireless connections or peripherals. ArkOS (a custom firmware for linux handhelds) features a utility called Portmaster to get non-emulator programs onto the device, this is the loader for the M8 port.

What I'd like to see is something similar to the miniDexed project, using Portmaster to launch Dexed rather than running it baremetal off a Raspberry Pi. The UI would be limited, but it could fit quite a bit more than the 32 characters miniDexed can do. A keyboard/controller could be connected through the OTG port and most of these handhelds come with a 3.5mm jack for stereo audio out.

I'm sure the audio quality wouldn't be great, and it would probably be limited to one tone generator, but I like the idea of having a single device that can run M8, LSDJ, Nanoloop, and Dexed. These devices being already built, cheap, battery powered, and extremely portable is a plus too.

I don't have much application development experience, but I'd like to get an idea of the hurdles that would be involved with making a go at this. I'd be in over my head, but I feel like all the pieces are right there spread across a few github pages.

So I have a little VCO set up and now I'm trying to control it with a keyboard. I don't actually have a CV source so I made a little voltage divider and button setup. I put in 9V, and divide it to 3V using resistors and then capture the output using an audio jack which controls the VCO.

I basically want to expand this into a 2 octave keyboard but I'm not sure what I should make the resistor values or how to connect the buttons together. I'm really new to electronics so when I tried looking it up online I was a bit overloaded with info lol. Much love and appreciate everything

I'm looking for a main board for the Roland JD-800.

I aim to preserve the main CPU code using a logic analyzer.

I am an ambient/drone guitarist, and I mostly use Reaktor via Ableton for my effects. This post is to determine if a product exists or if I’ll have to build it myself. If it’s the latter, hopefully someone has some advice.

I watched a video a few years ago with Squarepusher showing an interviewer around his home studio and at one point, he was showing off a pretty large expression pedal setup he uses to control his bass sound, and I’m guessing he somehow has this big board of EV5 expression pedals routed into Reaktor.

The video in question is here https://youtu.be/zEofbwt0zRY?si=aoFAf5xQ__8HG1CX and the part I’m talking about is at around the 7:10 mark.

Now for the questions. Does a product that receives multiple signals from expression pedals (TRS connections) then send them through USB already exist, or would I need to build such a device? Would it be feasible to get my hands on one of those DIY Arduino kits and use TRS jacks instead of linear pots, which I would then be able to plug passive expression pedals into? What considerations would need to be made if building this?

I’ve never “built” anything but I’m not completely uninformed on the science behind it, so I think I could figure it out if I had to build it.

Any thoughts?