Hi. I've tried to build the Aion Solaris PCB. But, after trying the pcb the signal goes oscillating. And sound is quite noticeable about 10kHZ freq.
The IC Pump is ICL7660 with frequency boost feature, but it doesn't seem gets engaging. Tried to mess with the caps, but it doesn't get better.
Is there any way to eliminate that noise?
So, the frequency boost is supposed to take it from 10k (what you are hearing) to around 50k, IIRC. Are you using the SCPA version or the CPA version of the 7660? You need to use the SCPA version. If you are, then you might try a different inverter. The MAX1044 or TC1044. Just so it's more confusing the correct MAX version is the CPA and correct TC1044 version is SCPA.
Quote from: madbean on November 23, 2017, 01:27:59 PM
So, the frequency boost is supposed to take it from 10k (what you are hearing) to around 50k, IIRC. Are you using the SCPA version or the CPA version of the 7660? You need to use the SCPA version. If you are, then you might try a different inverter. The MAX1044 or TC1044. Just so it's more confusing the correct MAX version is the CPA and correct TC1044 version is SCPA.
Thank you, Brian. I'll start with trying tc1044 (the scpa one).
Once you do that, if you still have issues, try bumping up the value of the -9V filter caps. I've had Tonebenders that oscillated with a 10uF filter cap, but once I bumped it up to 22 or 47uF it went away. Seems to be an issue that sometimes crops up when running PNP germanium transistors from a charge pump.
Quote from: aion on November 23, 2017, 03:42:58 PM
Once you do that, if you still have issues, try bumping up the value of the -9V filter caps. I've had Tonebenders that oscillated with a 10uF filter cap, but once I bumped it up to 22 or 47uF it went away. Seems to be an issue that sometimes crops up when running PNP germanium transistors from a charge pump.
Thank you, Kevin. I changed the value for a 47uF and poof! the hiss is gone. ;D
Awesome, glad that helped! In my experience it seems to be based on the transistor itself... some of them need a higher filter cap, some don't - just one more characteristic that makes germaniums what they are :)