I have a noninverting opamp config with 10x gain. When input is 0V, output is > 0V, ie, there is voltage offset. I want to eliminate this offset by injecting some millivolts to the (-)input using a pot. As the picture shows, I'm connecting the swipe lead of the pot to the (-)input of opamp. This works as I can adjust the pot so that 0V appears at the output when (-)input is tied to ground. My question is: Should I put a series resistor between swipe lead of pot and (-)input of opamp? And what size resistor, thanks!
Rich (BB code):
10k
----/\/\/\-------
| |
| |\ |
Vin ---/\/\/\------------------|-\ |
1k | | \_|__Vout
| | /
| GND--|+/
resistor? |/
here?
|
|
5V---/\/\/\---------(-12V)
20k pot