Is my OpAmp bad?
IamSmooth, Mon Sept 04 2006, 03:57AMI have a Norton OpAmp and I think it is shot. I connected Vcc to pin 14 and Ground to pin 7. When I connected voltages to the + and - inputs nothing seemed to happen. In fact, when I put 2v on pin 3 and measured the voltage it was 0.7. Is there anyway to tell if the chip is bad or is this sufficient evidence?
Re: Is my OpAmp bad?
Steve Conner, Mon Sept 04 2006, 11:26AM
No, the part number of the chip would help. By Norton op-amp do you mean an OTA? or a current feedback op-amp? Neither of these behaves much like a regular op-amp, so if you were expecting regular op-amp behaviour, you might well think it was broken. (Or even break it by wiring it up like a regular op-amp.)
Steve Conner, Mon Sept 04 2006, 11:26AM
No, the part number of the chip would help. By Norton op-amp do you mean an OTA? or a current feedback op-amp? Neither of these behaves much like a regular op-amp, so if you were expecting regular op-amp behaviour, you might well think it was broken. (Or even break it by wiring it up like a regular op-amp.)
Re: Is my OpAmp bad?
HV Enthusiast, Mon Sept 04 2006, 12:29PM
Part number and schematic of how you are hooking it up would help.
HV Enthusiast, Mon Sept 04 2006, 12:29PM
Part number and schematic of how you are hooking it up would help.
Re: Is my OpAmp bad?
IamSmooth, Mon Sept 04 2006, 03:59PM
This is the OpAmp I was monkeying with:
I connected a 2k resistor - 2k pot - 2k resistor series from Vcc to Gnd.
I connected the 3900 to a 5v supply and the resistors to a the same 5v supply.
I connected a triangle wave source to 2IN+ (pin2) and I connected the pot to 2VIN- (pin3)
Nothing happened at 2OUT.
EDIT:
I decided to hook up the opamp with some resistors (1k into VIN- and 2k from VIN- to Vout) so I get a 2x amp. I put a triangle wave in and could see that it did double the voltage on the positive side. This brough up a question:
1. I though the LM3900N, with a single positive voltage supply, could work with positive and negative signals.
IamSmooth, Mon Sept 04 2006, 03:59PM
This is the OpAmp I was monkeying with:
I connected a 2k resistor - 2k pot - 2k resistor series from Vcc to Gnd.
I connected the 3900 to a 5v supply and the resistors to a the same 5v supply.
I connected a triangle wave source to 2IN+ (pin2) and I connected the pot to 2VIN- (pin3)
Nothing happened at 2OUT.
EDIT:
I decided to hook up the opamp with some resistors (1k into VIN- and 2k from VIN- to Vout) so I get a 2x amp. I put a triangle wave in and could see that it did double the voltage on the positive side. This brough up a question:
1. I though the LM3900N, with a single positive voltage supply, could work with positive and negative signals.
Re: Is my OpAmp bad?
Steve Conner, Mon Sept 04 2006, 04:40PM
That's a current-feedback op-amp, you have to apply it in a completely different way to a normal one:
Steve Conner, Mon Sept 04 2006, 04:40PM
That's a current-feedback op-amp, you have to apply it in a completely different way to a normal one:
Re: Is my OpAmp bad?
IamSmooth, Mon Sept 04 2006, 04:45PM
thanks steve.
IamSmooth, Mon Sept 04 2006, 04:45PM
thanks steve.
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