Hello all im looking to build some somewhat easy/simple probably well documented chaotic/feedback or both module;

For example im looking into this IC's

CD4011

CD4040

and of course something like an op-amp

TL072 / TL084 / LM358

Tell me any idea or project you have anything is helpfull !

UPDATE: I fixed it.

Hello, I am replacing a bad display on a Roland Alpha Juno 2 with an OLED aftermarket part, but this display requires replacing the firmware EPROM. I used a desoldering gun to remove most of the solder holding the original EPROM, but I still had to use some force to detach it from the main PCB. I noticed that I damaged some of the eyelets on the PCB. I attempted to repair the eyelets by putting a small piece of wire through them. I used a multimeter to check the connections with the new EPROM, and they all seem good. The synth turns on and shows the "CHECK BATTERY !!" message on the display, but it will not do a factory reset when I do the factory reset procedure [Holding down "PORTA-MENTO" and "DATA TRANSFER" while switching the synth ON]. The battery was recently replaced. The buttons are operational as they change lights or the display when I press them. It will also not receive new patch banks over MIDI properly; the patch names are transferred properly but the patch data does not load properly. The preset ROM patches still work fine. Do you have any suggestions? I would have a professional fix this, but I do not have a synth repair shop nearby.

Hey guys. I have a rather bad habit of buying parts for things I'm working on before I have finished the design, and then changing it beyond recognition so those parts are no longer relevant. As a result I've now got a selection of interface components (buttons, knobs, switches and pots) that I'm unlikely to use. They're all from Thonk, so they're high-quality and fairly commonplace parts that would suit most projects. Would anyone be interested in buying some / all? Here's a list of what I've got: https://felixbaileymurray.notion.site/161040dc69608013a612ca9dc7746cd6?v=ca47e61656be444e9f4c7c0bb4c3c297&pvs=74

Selling at reduced rates compared to Thonk, obviously. I'm in the UK, so you'd have to also be UK-based.

Hey everyone! Beginner noob builder here. I've made a couple of Atari Punk Consoles, one with LPF on the output - quite satisfied with the result. Now my next ambition is to design a dual-voice one - basically two APC's in one case, mixed together on the out. But here my troubles begin. Both 556 chips and all the pots are connected to the same + power rail (9v), and seems like they drain power from each other. For example, even when the sound output of my OSC2 is not connected to anything, twisting its corresponding knobs affect the pitch of OSC1.

Going through my stuff and I have this PCB but can't find parts list/build notes anywhere online

:( .. i see GMSN are not doing stuff any more.. but any advice on how I locate the information?

I need to get this little project moving.. :(

I'm learning electronics by making synth modules and messing around with associated circuits. I have a lot of programming experience, and a bit of electronics now.

I found a cheap toy synthesizer at a thrift store and have figured out how to scan the button matrix with an Arduino to recognize when keys are pressed and released. I think it would be fairly simple to output midi messages, though I've never done that before.

What I'm really curious about right now: how would I output CV if I wanted to control a polyphonic euro rack module system? I know I'd need all the modules for multiple voices (let's say 4 for example). And I've already read that that's not realistic, and it's expensive, and it's a headache to keep them synchronized and so on. So let's say I'm not going to do it, I just want to know how it's done.

I'm assuming I need four (or whatever number) of CV outputs from the keyboard (or the midi to CV module I would make). Those CV outputs could be based on DACs controlled from the Arduino.

The part I'm specifically curious about: when a key is pressed, how do you determine which DAC-output to send the note/CV through? If I'm holding down one key while jabbing quickly at three other keys, what does the routing from keypress to output look like? Is it just clever programming to keep track of what outputs are in use? Is there some other trick or chip that gets used?

Just to reiterate: I don't want to buy modules that would do this. I want to know how the output routing can be done. Thanks for your help!

Hello! I've been lurking this sub for a while, but have yet to dip my toes into DIY. I have a pretty decent eurorack system, coming up to around 1100hp now, and I am very much into utilities, I try to keep my rack around 30-40% utilities at all times. As I add more oscillators or fx or whatever, I add more utilities to modulate them.

So, the idea I have is to make a replica of the Make Noise shared system CV bus, but without the need for the left hand side sum inputs, or the right hand side outputs. That space could be used for an extra set, like this. (5 sets of 4, instead of the MN 4 sets of 4.) I would want it to be passive, like the MN bus, not like the buffered Lange Anna. I would be thinking of making 2 or 3 of them, to put in 1U rows across multiple cases. Is this an easy build for a beginner? It could be completely passive in the sense of zero power, or passive in the sense of unbuffered, but powered from the busboard to run led's. I'd kinda like the led's actually, to help make patching easier.

Lastly, if this is doable - Is there a build guide out there that I could copy from and expand on? I'd be looking to make each one 104hp, and fit as many sets in as possible. If I could even stretch it to 6 sets of 4 in a 104hp, I'd do it, because it's just jacks in and out, no knobs or controls. It would be totally okay to have the jacks stacked closely together as long as that didn't create any potential tech issues like shorting solder points or anything.

I'd be happy to invest in a good soldering iron (I know the Hakko brand is supposed to be good quality) and the right additional equipment to get into it. I haven't done so yet, but now that I have an idea that I want to make, which nobody really seems to be selling, maybe it's time.

Any advice is much appreciated. Thank you.

I have an old Vermona organ and want to make a harmonic percussion pedal for it, since it does not have it. (harmonic percussion: in Hammond organs there is a switch, if you turn it on, the sound will decay after pressing the key like in a piano) This organ does not have a gate out, so the only way to know if a note is pressed is when there is a sudden voltage jump in the signal. Is there a schematic for this somewhere?

https://preview.redd.it/93yfq46xmp7e1.png?width=1015&format=png&auto=webp&s=344c831e4c3453acb5a8efb6eaeaf656d3c26507

So I'm still trying to wrangle this into something I really like (instead of sorta like) and I've come to discover it's WAY TOO LOUD, and thus way too noisy.

The 100k resistor tames the output level, but I feel like it needs to be a higher value.

So my question, is there a way to make an educated guess on what the value should be? I have a good amount of resistors on hand, I'm just trying to avoid trial and error with every single one. I also have a multimeter to measure...whatever it is that needs to be measured lol. I'm really a noob at this!

EDIT: My goal is to get this to be more friendly with guitar pedals. So my initial guess is something in line with the output level of an average humbucker style guitar. Of course synths can be used with guitar pedals as well but I'm not sure how 'hot' the output of the average, off-the-shelf (moog,korg, etc) synth is.

Hi everyone,

Recently my very old Keyboard (a Fatar studio 900) broke and it seems the mainboard is dead. I have almost no experience with electronics but I know how to program which is why I have an Arduino (leonardo) laying around. Is it possible to connect the keybed of the Fatar 900 (couldn't find out what keybed it is) to the arduino and send midi from that to a computer via usb midi (which the arduino supports)?
I haven't found much information about my keyboard besides this older webpage which used to sell replacement parts. It appears that the keybed has two 20-pin ribbon cables which I've never seen before and don't know how I'd get those connected in the first place.

After roughly a year of fiddling and build I got my first case done. I always wanted to stay truly DIY but caved when the cyberweekend at Thomann came. Couldn't find schematics for Maths anyway and it does so much.

In total I got two Behringer modules (power and maths) and a kit from Erica Synths. The rest is either copied or adapted from open source schematics.

The Patch.inits run Rings, Clouds and my own take on the gamut repetitor.

You can find all KiCad Projects in my GitHub.

Cheers

Hello,i was wondering if it would be possible to change the keybed of the Nektar GX 61 with a Fatar TP9/S keybed.

I really like this keybed and it would cost around 150€+100€ the nektar impact gx.

This would still be cheaper than buying the NI Komplete Kontrol 61 which costs around 700€.

So my question is, would this be possible?

I know the keys are probably different measured and i would need to adjust the case a bit but electronic wise could i just swap them?

The fatar keybed has 2 micromatch 16 pin connectors but i'm not sure about the nektar keybed

I have a couple of kit Synths that have those touch plates to play and adjust the sound. I'm thinking about mounting to a board and adding some vactrols to give them cv input to modulate without my fingers. Should that work? I notice each plate has 3 holes so was thinking these are equivalent to the 3 pins on a pot. Has anyone done this before, don't want to fry anything. Many thanks.

I'm toying with building a arduino/raspPi midi to CV module -- There are plenty of 1 channel ones around -- anyone know of a 4 or 8 (or even 16) channel one? (Or would it just be easier to daisy-chain 8 1 channel modules)

Hi everyone! I've been very interested in messing around with synths and I see many people talking about producer friendly projects etc. I don't really have interest in making any music, at all. I just want to make a (wonky) machine with my hands that output a funny noise haha it is 100% a hobby thing, but a hobby that I am willing to learn eletronics to achieve.

Been researching for a few days now and it seem like an Atari Punk Console would be a fun first project. I was wondering what would be other simple yet funny sounding modules I could build?

Since I live in Brasil I think the components might not be as cheap as they seem to be out there, so I thought it would be smart to plan a few projects ahead so that I could buy a kit / pack with more components and maybe get a better deal at it?

I would like to "automate" as little as possible. Not sure if that's the word here, but using something like an Arduino feels weird to me, it's kinda like if I want to open a coconut and someone handed me a jackhammer. Does that make sense?

Idk, I just want to have a mad sound scientist phase for some months hehe

Hi,
I'm right now deciding on whether to make my next modules banana or 3.5mm, and I was wondering about how mults with banana cables work? Whenever I search about banana cables, this turns up as one of the pros of bananas, but I don't fully understand how it works? Especially since I know that some mults preferably are buffered which the bananas would not be. Are there any risks? What do I need to know? I'm pretty interested in trying to build a banana system.

Thanks :)

Hi, anyone know of a source for these type of switches found on a lot of synths and audio gear? Not having any luck finding a supplier.

Thanks for the help.

Heya! I needed a fairly versaitaile VCO with minimal components for a project, and this is what I came up with today, I'm sharing the schematic here in case anyone else is looking for or needs one. It uses one single TL074 op amp, and runs on a single 9v supply, like a battery or guitar pedal adapter. It can generate a sawtooth, spike, square (wirh variable pulse width) and triangle. Minimal design requires 8 resistors, 1 tl074 (or similar) quad op amp, 1 diode, 3 capacitors and 2 transistors, so it's a fairly component light oscillator. It of course does not track v/oct, but that was not needed for my project. The pulse width control, which also affects the shape of the triangle is quite finicky, and couls do with more resistors to narrow in the range of the pot to be less finicky, but i avoided it here because of the desired minimal components. Hope someone can find it useful :)

I found a beauty on the street about ten years back, someone had snipped off the power cord so I put a new one on and it served me fine since then. Recently though, all the notes stopped working. The power works fine, I can switch it on, and all the rhythms still play, but any time I hit any of the keys, all I hear is a faint 'pop' sound and that's it. Obviously I've tried all sorts of combinations of the effects etc. I know that certain contacts could go here and there, but since they all went at once I'm wondering if it could be one part that I could fix. Does anyone have any experience with these old things? Only detail I have is from the writing on the front and the make date inside the back, "Lowrey Debut with Magic Genie Chords" "Feb 1978“

Hey fine folks of SynthDIY, I am looking to diy a mutable Marbles, but am not finding the calibration procedures anywhere in the GitHub, only references to old forum posts and 404'ing gits.

Does anyone have a procedure saved they could share with me?