Neutron is working...still need a little help though

[DaveTV]

I've got the Neutron up and running and it sounds great for the most part. However, when I change the Direction switch to the "Down" position, I get a high pitched whine. I also seem to get this whine in the "High Pass" setting with the Direction switch in the "Up" position.

Yes, I'm using the 7660 chip in this circuit, but I've eliminated the On/Off transistor, since I only use a 9V power supply--no batteries to drain. The power supply's + connectes directly to the 8 pin. I basically turn it on when I plug the power supply in.

Since I'm using a 3PDT switch for true bypass, I've eliminated the bypass connection shown on the schematic.

Otherwise, everything else is as shown. I understand that using the 7660 chip can cause a high pitched whine, but would it go away at some settings? Would any of the changes I made cause for this whine? Did I read something about connecting the 1 and 8 pins on the 7660?

Any help is appreciated.

[Capaletti69]

Im having the exact same problem and mine is wired the exact same way and powered the same way as listed above, anyone...Im using a max 1044, jumping pins 1 and 8 got rid of the whine but i lost some sensitivity as well.

[R.G.]

The 7660 switches at a frequency that is within the audio band. If you use it, you will hear some whine. Period.

The MAX1044 can be made to switch at higher than audio frequencies by connecting pin 1 and pin 8. The whine is still there, but you cannot hear it. The 7660 does NOT do the faster switching if you connect pin 1 to pin 8. It's an older, and less functional chip. You can also use the LT1054, which also is above audio, and does not whine.


The MAX1044 having pin 1 and 8 connected has nothing to do with any sensitivity changes. It can't.

[zeta55]

There are different versions of the 7660 circuit.
7660ACPA dodes not have the boost option, the 7660SCPA do.

/Krister