Why am I getting Vout = Vsupply in my op amp circuit?

[ponjavic]

Hi!

I solder the following circuit:
http://en.wikipedia.org/wiki/File:Op-Amp_Non-Inverting_Amplifier.svg

With an opamp of +-5V or 0-10V operation

I use a 12V dc supply and give a Vin of 0.05V with resistors 10k and 1k.

For all cases no matter what I supply I get Vout = Vsupply.


Then we stripped everything nad just tried to supply v- and v+ 1.0001 and 1.0002 and still got Vout = Vsupply

Any ideas?

 

[berkeman]

Hi!

I solder the following circuit:
http://en.wikipedia.org/wiki/File:Op-Amp_Non-Inverting_Amplifier.svg

With an opamp of +-5V or 0-10V operation

I use a 12V dc supply and give a Vin of 0.05V with resistors 10k and 1k.

For all cases no matter what I supply I get Vout = Vsupply.


Then we stripped everything nad just tried to supply v- and v+ 1.0001 and 1.0002 and still got Vout = Vsupply

Any ideas?

Stay with the +/-5V supplies for now. When you put in 0V, you should get out 0v.

If you don't, double-check the pinout of the opamp to be sure you are connecting it correctly. Try a 2nd opamp chip in case the first one is blown. You do have the opamp chip socketed, right?

Double-check the resistances with a DVM. Maybe the resistors are not what you think, or are damaged. Check the resistances with the power off.

 

[vk6kro]

Hi!

I solder the following circuit:
http://en.wikipedia.org/wiki/File:Op-Amp_Non-Inverting_Amplifier.svg

With an opamp of +-5V or 0-10V operation

I use a 12V dc supply and give a Vin of 0.05V with resistors 10k and 1k.

For all cases no matter what I supply I get Vout = Vsupply.Then we stripped everything nad just tried to supply v- and v+ 1.0001 and 1.0002 and still got Vout = Vsupply

Any ideas?

The circuit in Wikipedia assumes a dual voltage power supply.
If you want to use one power supply, you need to do this:
[PLAIN]http://dl.dropbox.com/u/4222062/opamp%20non%20inv%20bias.PNG

This will have a gain of 9 but centred around 6 volts.
So, 6 volts in gives 6 volts out.
6.1 volts in gives (6 V + (9 * 0.1)) or 6.9 volts out.
6.5 volts in gives (6 V + (9 * 0.5)) or 10.5 volts out.
5.8 volts in gives (6 volts - (9 * 0.2)) or 4.2 volts out.