Kittywampus Charge Pump Whine

[Tremster]

I built the Kittywampus (Mr. Black Thunderclaw) that whines like crazy.
The pedal calls for an LT1054 charge pump, I used an LT1054CP (isn't that the only 1054 you can get?).
If I put in an ICL7660SCPAZ the pedal is quiet and works fine.
It's weird that the "correct" IC doesn't work and the other one does. Should I just leave the 7660 in? Get a different 1054?
Can I link or cut some pins on the 1054 to make it work?
Anything else to consider if I leave the 7660?
Thank you.

 

[jwin615]

No schem posted yet
Curious about the frequency cap
I'd advise trying it on isolated power and see if it goes away.
If it does, but comes back when on a circuit with other pump pedals, you'll need to use a different pump or maybe try changing the frequency with a different cap value
See bottom of page 10 on the datasheet

https://www.ti.com/lit/ds/symlink/lt1054.pdf?ts=1722304403120

 

[jesuscrisp]

Are pin 1 and 8 of the charge pump IC connected?

 

[Tremster]

Are pin 1 and 8 of the charge pump IC connected?

Tried that now and only got a low humming noise.
Also lifted up the leg of pin 1 but the whine remained.

 

[Tremster]

I'd advise trying it on isolated power and see if it goes away.

No success.

 

[music6000]

1. Are Pin 1 & 8 connected on the PCB?, that is where their may be an issue & why the 7660S is OK???
2. Where did you get the LT1054CP's from?

 

[Tremster]

1. Are Pin 1 & 8 connected on the PCB?, that is where their may be an issue & why the 7660S is OK???

I don't know, not visibly. There is no schematic/build doc yet.

2. Where did you get the LT1054CP's from?

UK Electronic in Germany, tried and true reputable seller, I have been buying theer for ten years.

 

[music6000]

You should see a trace either top or bottom of the pcb going straight from Pin 1 to Pin 8 or with the power unplugged & IC removed, test for Continuity.

 

[andrewsrea]

Yep - not all the LT1054's are the same and not all the 7660's are the same, when it comes to hearing sub harmonics of the internal clock / switching oscillator. IDK if it is shielding, filtering or both. All will step up the voltage exactly the same, but only particular suffix types will be silent.

That is why I exclusively use the ICL7660SCPAZ. Functions reliably.

 

[Tremster]

Sorry for the late reply, busy days.

You should see a trace either top or bottom of the pcb going straight from Pin 1 to Pin 8 or with the power unplugged & IC removed, test for Continuity.

I don't see a trace and get no continuity with the power off and the IC removed.
I'll just leave the 7660 in and be done with it.

 

[music6000]

There will be a trace in order for the the 7660SCPAZ to work correctly!
It's the only one I use & have recommended others that have had issues with the TC1044S with the same issue you had here.
The only advantage the LT1054 is it can handle up to 15v input & double to around 28v + -.

 

[Tremster]

It's a rather nice "Orange" distortion, btw.

 

[Robert]

There's a trace under the charge pump.

It's a little concerning that you don't read continuity between those points, but if it's working with a 7660 there's really no need to change it.