McSpunckle FX Schematics

[Teej212]

ive gotta question- what are the dual gang pots for that I see in some of the gut shots? they arent in this schematic? also, are those trimmer the ones that you have access to on the side of the pedal?

[McSpunckle]

ive gotta question- what are the dual gang pots for that I see in some of the gut shots? they arent in this schematic? also, are those trimmer the ones that you have access to on the side of the pedal?

I think you're talking about the rotary switches I did on a few pedals. They had the function of the "diode" switches, but with 6 positions instead of 3 (also, I just realized the diode switches should be labeled "On/off/on" in the schematic).

I stopped using them because there was barely enough room for them and I didn't think they added as much as they should.

And yup. The trimmers in the schematic are the little pots on the side of the pedal. The starve control is actually on the back. It just made the schematic cleaner to use trimmer symbols when possible.

[azrael]

oh man. Gnomeratron schematic is down. I can kind of make out what's going on...Heard it had Muff elements....but oh man, lots going on in there! Care to explain your thought process when you came up with the circuit, McSpunckle?

[McSpunckle]

oh man. Gnomeratron schematic is down. I can kind of make out what's going on...Heard it had Muff elements....but oh man, lots going on in there! Care to explain your thought process when you came up with the circuit, McSpunckle?

Uploaded it again. Must have gone down when the servers went weird.

The idea was basically to make a more versatile/weirder Brassmaster. I used the Muff circuit because it was super versatile. I tried to actually use something from a Brassmaster, but it really just ended up having nothing but the fact it has clean blend and octave in common. The octave is based on the Green Ringer/Tone machine style. It's placement is like a Tone Machine... though I didn't really realize that 'till after the fact. I just wanted it to be able to go into another clipping stage, so it made sense to stick it in the middle.

The Muff part is really stripped down. I took out all the limiters and high end filters. So it's basically an opened up "tone wickered" Muff.

Originally it didn't have the input splitter and the clean and fuzz shared the last stage of the fuzz circuit. When I had PCBs made I upgraded it since I had room to do it. It originally didn't have 4 of the switches or a starve control either. But those are fun, and it's a neat way to mount the trimmer PCB anyhow.

[azrael]

Oh, you've moved to PCBs? I had only seen gutshots when it was just perf (I think? I remember seeing it and being impressed with how much time must have been spent on it). That must have been a big improvement in build time.
Do you have any pics? Where did you go to get them fabbed?

[McSpunckle]

It helps a lot. It's due for another redesign, though.

http://www.flickr.com/photos/51572438@N ... otostream/

I had the PCBs done by Pad2Pad. The PCBs are great, but I mostly used them because of their simple design program (and their prices were pretty solid). Next time I'm going to use Eagle for the layout and order from somewhere else, probably. Once I run out of PCBs.

[Seiche]

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[McSpunckle]

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Haha. yeah! I have no problem with that. It's a fairly simple circuit, but there's 5 of them, and the parts are weird and sorta expensive.

I'll see if I can't get something up later today.

[McSpunckle]

Check the first post, yo!

[Seiche]

Thanks bro!

hmm interesting, so you take the 5v, juice them up to 12v and then needle-eye them back to 9v. why not use a 9v supply? because there are none with enough juice (mA)?
And that Recom thing costs about 8 bucks, and you've got five of them in there? wtf.

I'm interested in what you come up with in the new version

[McSpunckle]

The new version likely won't be cheaper to build, but it'll be far more efficient.

Anyways, the 5V input voltage is just because it seemed like a good option for the input. Wall warts are easy to find, and you can use USB power, which is fun. The Recom chips are isolated, but not regulated, so they go up to 12V, and I use a linear regulator. Linears are supposed to be super quiet, too. According to Voodoo Labs anyways, but I suspect that's just their excuse for not making a switching supply. Recom sells a couple of regulated ones with 9V out. One's linear, and one's switching, but they're both a lot more expensive. I wanted to use something like a flyback converter, but the prices for the chips and transformers were way too high and/or I had to buy 1000s of parts, which I can't afford to do.

Alas, this method works well. It's pretty simple, too. It's just inefficient. It's a bit more expensive, but so are most of the transformers used in normal power supplies. One Team Tesla costs me about $50 to build... I guess it'd cost quite a bit more to build just one, though.

The new chips will be a big improvement on efficiency, but the whole thing will be SMD.