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kinjalgp said:1) Mount 741 on bread board
2) Connect Vcc and -Vee (+-15V)
3) Connect both the input terminals to ground. The output should be approximately 0V.
4) Now connect NI terminal to Vcc. The output should also be Vcc. And if it is connected to -Vee, the output will be -Vee.
5) You can even test the same thing with NI grounded and I given Vcc or -Vee. The output in this case would be Vcc when I connected to -Vee and -Vee when connected to Vcc.
Thats it.
Note that at 3) the amp is running at max gain, and the output may go up to V+ or down to V- depending on the input offsets.
It depends what voltage 'ground' refers to. You said connect Vcc and Vee to +-15v. I assumed that ground was 0v = half rail. Under those circumstances it is extremely unlikely that the output would also be half rail.kinjalgp said:Note that at 3) the amp is running at max gain, and the output may go up to V+ or down to V- depending on the input offsets.
If both the inputs are grounded, the output should be ideally zero. I have observed that for 741 in open loop configuration, the output is around 2.5V when both the inputs are at 0V without any offset adjustment.
Here if you connect both inputs to -Vee the output swings to +Vcc and if both inputs are conneted to Vcc the output swings to -Vee. So this is a test. Just check this funny behaviour on breadboardIf ground refers to Vee then there would be no bias current for the input stages, so it would not really be a test.
kinjalgp said:Here ground refers to 0V i.e between +15 and -15. Now if you practically check the output of 741 with both inputs connected to 0V the output is at +2.5V. And even in simulation the output shows 2.439V. This is due to very very very small offset present between two inputs.
Here if you connect both inputs to -Vee the output swings to +Vcc and if both inputs are conneted to Vcc the output swings to -Vee. So this is a test. Just check this funny behaviour on breadboardIf ground refers to Vee then there would be no bias current for the input stages, so it would not really be a test.
Thanks. I'm glad you agree with me .kinjalgp said:Your explaination is correct Pebe. There are chances that my Op-amp was faulty or may be it is due to device to device parameter variations. Op-amps of different make can also cause this problem. Mine is National semiconductors LM741. What about yours?