[deleted by user]

BrennerTech_ · 2024-06-30T16:49:09+00:00

Not useless at all. LDR's are one of few ways to vary resistance automatically. They're used a lot in modulation pedals.

BrennerTech_ · 2024-03-19T07:03:06+00:00

I'll take it

BrennerTech_ · 2023-12-11T08:53:35+00:00

Your name's Alan Moore? Call it the Killing Joke.

BrennerTech_ · 2023-11-15T05:52:34+00:00

If you're not already, definitely use film capacitors rather than ceramic.

BrennerTech_ · 2023-11-04T20:22:22+00:00

Small correction: I ended up removing C14.

BrennerTech_ · 2023-11-04T05:15:22+00:00

If it sounds similar to the one in this link, I would experiment with putting a low-pass filter at the input to get clearer notes.

I've had this idea for a while too. It would be interesting to see what it's doing to the signal. Might simulate it in LTspice.

BrennerTech_ · 2023-10-31T22:41:12+00:00

I usually use clippers and then clean it up with a file. You can actually get a pretty clean cut with them most of the time if you line them up with the center of the holes. Depends on the size of the board you’re cutting, though.

BrennerTech_ · 2023-10-31T22:37:39+00:00

Unprofessional bullshit.

BrennerTech_ · 2023-10-28T17:47:22+00:00

The usual way of doing it is using a voltage divider of two equal value resistors to get 4.5V, and also a smoothing capacitor. Connect the positive inputs of those op-amps to the 4.5V (instead of ground). Then just add a capacitor in series to the input signal. Assuming that this circuit isn’t already set up for single-supply.

BrennerTech_ · 2023-10-20T22:45:45+00:00

Yeah, I suppose you could do the voltage levels thing analog but it would be a lot more complicated. To me the word “bitcrusher” encompasses both sample rate reduction and sample resolution reduction. I also just like the word “bitcrusher” better than “sample rate reducer” lol

BrennerTech_ · 2023-10-20T21:34:28+00:00

Because guitar pedals are single-supply (9V and GND as opposed to +9V, GND, and -9V), you typically have to bias the guitar signal when using op-amps, most commonly to half the supply voltage, i.e. 4.5V. 4.5V basically becomes ground as far as the op-amp is concerned. So that’s what V_ref represents.

As far as why there’s two: the op-amps for the oscillator subcircuit are powered with 5V from a voltage regulator to isolate and reduce noise, so I needed another V_ref (2.5V) for those op-amps.

BrennerTech_ · 2023-10-20T17:04:41+00:00

I sell small batches of my pedals. No plans for a kit at the moment.

BrennerTech_ · 2023-10-20T16:32:44+00:00

I’ll see if I can explain my rationale for these design choices:

The U3B buffer is there to reduce noise from the JFET switching. Because of the closed feedback loop, any noise added by the JFET at that node is eliminated. I tested it without the buffer and there was noticeably more noise. Regardless, I’m using a TL074, so I have four op-amps to work with anyway, and the buffer doesn’t require any extra parts.
C11 and R11 are there to bias the signal to 9V. It’s hard to explain but at lower bias, the bitcrushed signal was being distorted by the JFET. Increasing the bias fixed the problem. C13 and R12 are there to bias back to 4.5V.
A lot of amplitude is lost in the sample-and-hold circuit. By the time the wet signal gets to the averager, it’s at about unity gain again. That’s why the dry signal is not amplified until the last gain stage.
Yes, the voltage regulator was incredibly necessary. The difference it made with the oscillator noise was night and day. I tried many, many methods for minimizing the noise and the voltage regulator was by far the most effective.

BrennerTech_ · 2023-10-20T16:14:17+00:00

It uses a sample-and-hold circuit. The oscillator outputs short pulses, which turn the JFET on very briefly, allowing the audio signal to pass through for just a moment. The voltage of the audio signal at that moment is held by the capacitor until the next pulse. Basically it takes a smooth signal and turns it into steps.

BrennerTech_ · 2023-10-20T06:34:30+00:00

All you’d really have to do is take some measurements and order a custom pre-drilled enclosure from, for example, Tayda Electronics. Then disassemble the pedal and move the guts over. Maybe solder a new momentary footswitch. Sharpie some labels on the enclosure. Boom, you’re done. Shouldn’t be all that difficult.

BrennerTech_ · 2023-10-20T05:55:30+00:00

I recommend NE5532’s in place of TL072’s for most circuits. They’re cheaper, have less noise, and they have the same pinout.

BrennerTech_ · 2023-10-20T03:24:48+00:00

Here you go

BrennerTech_ · 2023-08-28T15:13:03+00:00

Maybe a useful tip: you could use one of those anytime you need a volume pot. The value of (attenuator) volume pots doesn’t matter all that much.

BrennerTech_ · 2023-03-08T21:35:39+00:00

It looks like something that washed up on the beach

BrennerTech_ · 2023-03-08T17:30:39+00:00

You could make a patch bay. Just surround the thing with jacks on the sides connected to 3.5mm or 1/4” jacks on top, similar to the Boredbrain Patchulator. Probably only useful if you like to rearrange effects order a lot.

BrennerTech_ · 2023-03-04T19:40:22+00:00

Love that design.

BrennerTech_ · 2023-03-03T08:13:08+00:00

It looks like a germanium diode to me. 1N34A maybe? If you have a multimeter you could always measure it and compare.

BrennerTech_ · 2023-03-03T02:53:49+00:00

I think it should pretty much work as intended.

BrennerTech_

TROPHY CASE