Problems with Quad OP AMP IC

Well, I am new here, and new to this hobby and I do not know if this the right sub-forum to post my question to.

I have constructed this circuit on a prototyping board:

https://www.circuitlab.com/circuit/875t83/receiver_1_4/

Each amplifier works fine as long as nothing else is connected to the chip. Once I connect a single resistance to the chip, the output of the amplifier goes high. The output on one of the amplifiers rises to 0.5 V while the second falls to -0.5 V. Both work properly but with the mentioned offsets. Now my question(s):

1-Why does this happen? 2-Can I avoid these effects or.. 3-That is normal and I have to eliminate these offsets, or... 4-Probably use two single OP-AMP chips instead

Thanks in advance

PS. I tried using TL084 instead of the LM324: same behavior.

by khier
March 27, 2013

Can you show what you are doing on your CL circuit?

Save your CL circuit under a new name and then add the components you are attempting to describe, run a DC and/or a sim transient and post it here.

If you've actually built it on a physical prototype board then the most likely thing is that you've just made one or more wiring mistakes.

Or it's oscillating.

Got access to a scope?

Can you post a link to a photo?

by signality
March 27, 2013

It is working fine on CL. The problem is in real life. The input signal is DC, something like 20 mV.

by khier
March 27, 2013

Well, I lied....

CL simulation shows identical 270 mV offset for zero input. This is half of what I get at home, and identical for both amplifiers, but it is not zero as I mentioned above. Funny though, I get 0 V when only one amplifier is wired and zero input applied.

by khier
March 27, 2013

Look down in the bottom right of the Editor window when you run your sim ...

Compare with:

by signality
March 27, 2013

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