tc1044 voltage pump

[sbirkenstock]

Hi Everybody,

I started tinkering with a tc1044 voltage pump.
I just put it on the side of my breadboard (did not connect anything the the existing cirquit), connected power (+9V), a 10mF Cap (bipolar) between Pin 2 and 4,
and a 25mF elecrolytic cap (just was sitting there, normaly I use them as kathode bypass for 12ax7 etc) between Pin 5 (Vout) and GND.
Perfect: Pin 5 delivers -9V.
Just the cirquit now puts a audible high pitch beep on my (very simple) boster circit (still running on 9v with a JFET).
Possibly the 10k hertz the chip uses.
Only connection shared between the TC1044 and the rest are GND and +9V.
I can see some ripple on the +9V supply on my oszilloscope.

So I tried to filter with a higher Cap Pin 5 to GND. (have seen 100mF in other Schematics).
Does not change too much.
Also I tried some filter caps from GND to +9v.
25mf, 100mf, 220mf, 470mf.
Did not change much.

Then I used Pin 1 of the TC1044 (Boost).
This made the "ripple" not audible any more.
But with the oszilliscope I can see it is still there, likely at 45k hertz?

Is there a way to isolate the TC1044 better, so the ripple goes away?
Of course you can not hear 45K hertz, but it might start some funny oszilations in the tube amp the stompbox will be connected to.

In general I saw several schematics (Booster, OD, Distortion) with "filter caps" from GND to +9v.
All kind of values. Any hint on the difference in that value and it´s effects?

Best regards,

Stephan

[blackieNYC]

That boost is increasing the frequency, presumably for audio purposes. This probably isnt a bad idea for charge pump circuits, if not every pedal - put a 8-12khz low pass filter on the input and output.
I believe RG is the loud advocate for only letting the frequencies you want get in or out of your circuit. 
45 (44.1)kHz  is trying to scream at you from every compact disc. We can't hear it, but we still filter it out. I thought the "boost" doubled to 20 kHz. Datasheet.

[greaser_au]

The high frequency performance of the average electrolytic capacitor is fairly poor.  A 100nF film or monolothic ceramic capacitor is often seen in parallel with the electrolytic in similar applications.  I suggest you might try this and see if it helps in this situation... 

david