Opamp Tester
Quick go/non-go testing for operational amplifiers
Published in issue 341, March 2005
Not a microcontroller in sight, and yet this item of test equipment will be found very handy in any electronics lab.
If you ever want to use an operational amplifier salvaged from an old circuit or from the junk box, you will take into account that the device may no longer work properly. Unfortunately, it is not as easy to perform a quick go/no-go test on an operational amplifier using a multimeter as it is with a resistor, coil, fuse, diode or even a capacitor. Although an opamp tester would obviously be a useful thing to have, a dedicated instrument is not easy to come by. However, you can build this item of test gear yourself in a few minutes, and it certainly won’t break the bank.
Unfortunately the printed circuit board for the above project contains a mistake concerning the supply voltage to the opamp in position IC4. However, the problem is easy to solve.
Using a sharp hobby knife, completely isolate pins 11 and 4 of IC4 from the rest of the circuit by cutting all copper tracks to these pins. On the IC socket, bend out pins 4 and 11 sideways and solder a short wire to each pin. Solder the IC socket in place (at the underside of the board). Connect the wire on socket pin 4 to the positive supply voltage. Connect the wire on socket pin 11 to the negative supply voltage.
Populate the rest of the board as indicated by the component mounting plan.
Please note that sockets IC2, IC3, IC4 and LEDs D1 through D16 have to be fitted at the solder side (underside) of the board. This allows the board to be better mounted in a case.
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Click below to download a PDF copy of this article from Elektor magazine. Please note. In view of the complexity of international markets, Elektor cannot guarantee the availability of components for this project.
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