Hijacking one pedal's charge pump to power another pedal

slowpogo

Active member
I want to pair the Mach 1 with the Cleaver in one enclosure. They should fit fine side by side in a 1590BB.

I already have a Mach 1 and I prefer to run it at 18V. However the Cleaver uses a charge pump to convert 9V to 18V internally. So you see the dilemma. If both pedals share one power input in parallel, then supplying 18V would accomplish what I want with the Mach 1, but would overload the Cleaver.

As a solution, can I power the Mach 1 in parallel with the 18V rail of the Cleaver's charge pump? Only the Cleaver would be connected to the pedal's power jack. To power the Mach 1 I would simply run a wire from the Cleaver's 18V rail (D102 cathode on the Cleaver maybe?) to the Mach 1's power input.

This way, I could power the pedal with 9V, but both would be running internally at 18V.

Would this work okay? any modifications needed to run the pedals this way?

 
You can do that. Tap the power at the +18V net on the Cleaver (i.e., D102 cathode) and supply the Mach 1 from there.

There are a few considerations:
  • The total current draw of the two pedals cannot exceed that of the charge pump rating.
  • You can bypass the polarity protection on the Mach 1.
  • The Mach 1 power filtering may be omitted as well, however, you may want to experiment to see if there is a change either way.

EDIT: I think that you're going to be close to the 20mA limit of the TC1044SCPA (given the published figures for the commercial pedals). In this case, you'll want to use a charge pump with a higher current rating (e.g., LT1054). Note that if you use an LT1054, you'll need to modify the Cleaver board: That board has a trace connecting pins 1 and 8 of IC100 that you'll need to cut so that those pins are no longer connected.
 
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Note that if you use an LT1054, you'll need to modify the Cleaver board: That board has a trace connecting pins 1 and 8 of IC100 that you'll need to cut so that those pins are no longer connected.

That has actually turned out to not be necessary, the LT1054 works fine with pins 1 and 8 jumpered.

It was discussed (and apparently verified by LT) a few years ago over on diysb.

They're connected in the original Aclam Dr. Robert as well.

I've stopped putting the solder jumpers on the bottom of the board and just leave them connected all the time now.
 
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Thanks much for the replies. I'm seeing 16mA total current draw for both pedals... I wouldn't have thought that was too close to 20mA, but if it's as easy as dropping in the LT1054, the additional headroom won't hurt.

This is meant to be an approximation of the EAE Limelight ("transparent" overdrive + boost) and I think it will be quite nice :D
 
That has actually turned out to not be necessary, the LT1054 works fine with pins 1 and 8 jumpered.

It was discussed (and apparently verified by LT) a few years ago over on diysb.

They're connected in the original Aclam Dr. Robert as well.
Gotcha, that's interesting. I always took it as best practice to remove the jumper between 1 and 8 and send Vcc to pin 8. Does that connection just nullify the FB/SD pin?

w/r/t total current draw, the published specs indicate ~16-17mA. I feel like that's a little close to 20mA, so I'd suggest using the higher rated pump.
 
I believe so, yes. According to the datasheet you pull pin 1 low to put the IC in shutdown, so I suppose pulling it low essentially does nothing.

I don't think I've seen a pedal circuit that uses the regulation function of the LT1054 so until we come across one of those it shouldn't be an issue.
 
Does this mean TC1044SCPA, LT1054 and ICL7660 are all interchangeable when used a voltage doubler and/or a voltage reverser?
 
As long as you keep withing the current rating, sharing a charge pump is better than putting two in one pedal. Their clocks aren't sync'ed and you will hear the beat freq. Been there, done that.
 
I believe you can sync the clocks with the LT1054. Never done it, but apparently the pin is there.

Actually the datasheet shows that it can accept an external oscillator, not sure if there's a way to tap the internal oscillator for that purpose though. (Maybe a sample from one of the other output pins before rectification/filtering?)

Just noticed the 1044 also has an external osc pin.
 
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That has actually turned out to not be necessary, the LT1054 works fine with pins 1 and 8 jumpered.

It was discussed (and apparently verified by LT) a few years ago over on diysb.

They're connected in the original Aclam Dr. Robert as well.

I've stopped putting the solder jumpers on the bottom of the board and just leave them connected all the time now.
@Robert This would be a really handy thing to have included in the current Muzzle Classic build documentation. I've spent (a small but not insignificant amount of) time trying to figure this out since my board has 1 & 8 connected and I'm using a 1054.
 
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