- #1
Omegatron
- 68
- 2
I've got a simple audio circuit that I wouldn't expect to have any signal coming out of it (the resistor at the input is a pot and is being grounded out).
But the previous stage's signal is still coming through:
http://img399.imageshack.us/img399/5804/opampinterferenceaz8.png
* It's not the contact resistance of the pot; I've soldered the terminals directly together and it's still there.
* 1/2 Vcc pin is perfectly flat relative to ground.
* Increasing the electrolytic cap didn't seem to have any effect
* There are two of these, and the crosstalk on one is higher amplitude than the other, though all the values are the same
* The crosstalk increases as frequency increases
So I'm suspecting some kind of inductive pickup in the pot (20k resistance)? Does that sound likely?
But the previous stage's signal is still coming through:
http://img399.imageshack.us/img399/5804/opampinterferenceaz8.png
* It's not the contact resistance of the pot; I've soldered the terminals directly together and it's still there.
* 1/2 Vcc pin is perfectly flat relative to ground.
* Increasing the electrolytic cap didn't seem to have any effect
* There are two of these, and the crosstalk on one is higher amplitude than the other, though all the values are the same
* The crosstalk increases as frequency increases
So I'm suspecting some kind of inductive pickup in the pot (20k resistance)? Does that sound likely?
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