Polyphase

Marcos - Munky · May 17, 2020, 12:47:33 PM

A battery powered guitar rig sounds very interesting. A few years ago, a few local bands used to play on public places, and they relied on some store to let them use a wall plug, or they used a fuel based power generator. The generator was nice and compact, and the fuel consumption was pretty low, but the power line was pretty dirty and the amps were noisy. Well, it worked at last.

Just a little math, the polyphase draws 80mA @ 18V, it's about the same power as 23 tube screamers (7mA @ 9V)! I found out about the current draw when I was doing some measurements yesterday and noticed my ICL7660 voltage doubler had about 13V at the output instead of 18V, then I used a 18V 1A power supply and measured the current draw.

Here's how I did the optos:

Still didn't got to solve the lfo issue. If I power it on with the switch set to lfo, it starts to work after a few seconds, but the leds doesn't turn fully off as in the envelope mode. Then, if I set the switch to envelope mode and then back to lfo mode, the lfo simply doesn't work at all.

idy · May 17, 2020, 01:06:16 PM

Those are two LDRs sandwiching an LED? What do they call those LEDs?

Marcos - Munky · May 17, 2020, 02:26:29 PM

Yep. The original optocoupler is a dual ldr one, so I have to improvise. Those are rectangular leds.

Fab66 · May 18, 2020, 05:06:46 AM

Hello Marcos.
In the schematic you have used there are some 10 Ohm resistors that are missing in the original schematic.
Did you put them?

Marcos - Munky · May 18, 2020, 09:50:08 AM

I followed Nelson's layout. The only thing I used the schematic for was to check which IC does what, to try to debug the lfo. It seems to be locked somehow, sometimes it works, sometimes it just lits the leds to full lit then stops working, sometimes it works back again. The envelope part is working very good. I mean, the modulation pots have little to no effect, but I'm pretty happy with the envelope part as it is.

Fab66 · May 19, 2020, 03:43:49 AM

Thank you

Fab66 · May 29, 2020, 12:04:01 AM

I think there is a mistake in the PCB
The pin 3 of CA3140 must be connected directly to the 15 uF capacitors, not through the 24k ohm resistors

PRR · May 29, 2020, 12:32:45 AM

> I used when playing for Northwood Morris.

Not an automobile?

"...recent clarification of Government guidelines, it seems there may be scope to maintain a more familiar form of Cotswold Morris..... due to greatly increased separation in the set, some dancers might not be able to hear the music. ..., the overwhelming majority of musicians observed that most of the dancers took no bloody notice of the music anyway and they really couldn't see this being a problem."
https://northwoodmorris.co.uk/various/coronovirus-and-the-lone-morris/

Marcos - Munky · May 29, 2020, 10:44:22 AM

Quote from: Fab66 on May 29, 2020, 12:04:01 AM
I think there is a mistake in the PCB
The pin 3 of CA3140 must be connected directly to the 15 uF capacitors, not through the 24k ohm resistors

Yep, good catch. According to the schematic, it should be connected like this:

I corrected mine, but I don't know when I'll be able to test it. Maybe later today.

StephenGiles · May 29, 2020, 01:29:42 PM

Quote from: PRR on May 29, 2020, 12:32:45 AM
> I used when playing for Northwood Morris.

Not an automobile?

"...recent clarification of Government guidelines, it seems there may be scope to maintain a more familiar form of Cotswold Morris..... due to greatly increased separation in the set, some dancers might not be able to hear the music. ..., the overwhelming majority of musicians observed that most of the dancers took no bloody notice of the music anyway and they really couldn’t see this being a problem."
https://northwoodmorris.co.uk/various/coronovirus-and-the-lone-morris/

Some very fine morris dancing here: https://www.youtube.com/watch?v=0QDKLglEP5Y

Marcos - Munky · May 30, 2020, 11:07:29 AM

I tested my build after the correction, and it's still the same issue. Working nice and beautiful on envelope mode (the best phaser I ever heard). On lfo mode, it works when it wants to. Most of the time, the lfo starts and, when the leds are full bright they just stays full bright, something is keeping the lfo locked. That's probably something related to my build, since there are reports of this layout to be working, even with the error on the layout. And that's probably how far I'm going with this circuit, at least for now. As nice as it is (it indeed worths to be boxed just for the envelope mode), it's very big, and I'm basically a 1590A guy. I do need a phaser on my pedalboard, but I'd have to remove 2 or 3 pedals to fit this one.

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