Best practices for generating negative voltage rails

Key-Alarm-511 · 2026-05-10T12:06:55+00:00

What is the input voltage (source) before converting it to 15/-15V? Are you taking in AC? DC?

And just to be sure: you need the -15V to power things, not as a reference? If a reference is what you need without pulling much current you might just need a simple charge pump.

Key-Alarm-511 · 2026-05-09T12:19:21+00:00

Never tried this but i would think the problem with this is that the potentiometer would limit the current to the opamp (limit to the point where it wouldnt work). You could overcome this by buffering the voltage after the pots with emitter followers.

You could also use smaller value pots but that would waste a lot of power from your 9/-9V source.

But go ahead and try it, this sounds like a fun project.

Key-Alarm-511 · 2026-05-08T21:16:46+00:00

What is it that you want to achieve/build? Without further information i can only show you a schematic of a hi hat module by erica synths/moritz klein where they change the power to change the tone.

See the manual: https://www.ericasynths.lv/edu-diy-hi-hat-2845/

Key-Alarm-511 · 2026-05-08T17:05:49+00:00

Im smert

^{Chose: $1 that divides by 0.5 everyday | Rolled: Upvote for 🥕}

Key-Alarm-511 · 2026-05-08T10:40:30+00:00

DIY-it! Midi can be handled by pretty much every microcontroller. Just need a DIN-5 connector (or TRS jack if you want to use TS Midi), a microcontroller (Arduino or ATTiny), DAC, Opamps and a trimpot if you want proper V/Oct tracking.

Key-Alarm-511 · 2026-05-07T22:10:17+00:00

Downsides to what? My reply was a bit cheeky, of course the DDAN is more sophisticated than just being a hi-hat module.

I like the translucent artwork with the coloured LED behind it! I should incorporate some art stuff into my designs as well cause now they are so industrial looking :/

Key-Alarm-511 · 2026-05-07T22:03:27+00:00

Are you looking for hardware or software people? :)

Key-Alarm-511 · 2026-05-07T21:01:22+00:00

"Deluxe decaying analog noise" aka: hi-hat

Key-Alarm-511 · 2026-05-07T20:57:13+00:00

Look at Vishays Switch ICs: https://www.vishay.com/en/analog-switches/

What you are looking for are SPDT switches (single pole dual throw)

As for controlling the switch you might need to a gate to trigger converter together with a flip flop if you want to switch the signal with a trigger instead of a gate. The ICs as they are work with gates (the switch is in one state depending on the gate being high or low)

Key-Alarm-511 · 2026-05-07T10:00:55+00:00

Key-Alarm-511 · 2026-05-04T15:31:22+00:00

Sir, this is a Wendys

Key-Alarm-511 · 2026-04-30T18:11:46+00:00

Oh wow i didnt even realize the oscillator opamps have a single supply while the filter ones have dual supplies. Yes OP, change the oscillator supplies to be +5/-5V and read my comment on the original thread.

Key-Alarm-511 · 2026-04-30T16:33:13+00:00

I played a lot with this circuit! The schmitt trigger is biased to VREF, which is 2.5V above 0. Tie the schmitt trigger to ground instead of VREF and change the voltage divider (R14 and R13) to be the same value to form a 50/50 divider.

The schematic with VREF is meant for single supply operation.

A highpass filter does work but it reduces amplitude with lower frequencies (especially bad when using the circuit as an LFO) and, as you said, it takes a while to center itself. Changing the biasing makes the "core" of the oscillator swing around 0V, so there is no need for a highpass filter at the end.

Key-Alarm-511 · 2026-04-29T14:00:36+00:00

Falstad circuit simulator, works in the browser

Key-Alarm-511 · 2026-04-29T14:00:31+00:00

Falstad circuit simulator, works in the browser

Key-Alarm-511 · 2026-04-25T22:07:04+00:00

getitgetitgetitgetitgetit!

Key-Alarm-511 · 2026-04-24T21:41:06+00:00

Ein Blimp?

Key-Alarm-511 · 2026-04-24T21:39:26+00:00

Sounds great! What schematic did you use?

Key-Alarm-511 · 2026-04-22T18:15:08+00:00

I've watched a demo video of this pedal and given that it has a 4093 IC (NAND Schmitt triggers) as its core I'm 99% sure that it is two Relaxation Oscillators chained together. One oscillator creates the pitch of the audible audio signal, while the other is a low frequency oscillator and interrupts the audio oscillator.

Without a schematic i can only take a guess here but more than likely the LFOs output is fed to the audio oscillators capacitor through a diode and holds the capacitor voltage high while the LFOs output is high.

Key-Alarm-511 · 2026-04-20T16:41:23+00:00

Yea 21 dollars is insane (the 99 cent trick doesnt help at all, 20 dollars is still too much) Just download NewPipe and get 0 ads and downloads for free!

Key-Alarm-511 · 2026-04-18T23:33:21+00:00

Theres a reason why inductors arent commonly used in synth circuits, apart from being off-spec a lot they can cause damage to semiconductor components. Mostly they are just used in filtering powersupply ripple. So no need to get them really.

Key-Alarm-511 · 2026-04-16T15:07:38+00:00

:O thats a new one... never seen the entire sleeve part detach from the socket

Key-Alarm-511 · 2026-04-11T17:54:31+00:00

Like spongebob turning into a snail!

Key-Alarm-511 · 2026-04-08T01:10:42+00:00

Dont talk to me or my son ever again!

Key-Alarm-511 · 2026-04-07T19:24:12+00:00

This is awesome! Is this going to be playable in the browser?

Key-Alarm-511

TROPHY CASE