Hi Folks,
In the past I have made a few inverting op-amp circuits with gains of 10, 50 and 100, these have worked OK. One that had been working for 5 years had a copper track peeling so I tried to make a replacement. I can breadboard circuits that work but when I solder them up I have been getting erratic readings and the meter would not zero. The track did eventually break and I had no choice but move all the components to another part of the same board, in spite of the fact it had worked OK for 5 years it would not now work. The problem, I suppose, is thermocouples at the solder joints, but I wonder why I didn’t get this problem before. I have tried a few things to overcome this problem without success, the latest was to solder resistors and wires directly to the IC, cutting out the usual IC socket and using prototype board without copper pads or tracks. The meter fluctuates between zero and 1.2 mV initially. It does amplify 1 mV to around 100 mV but of course includes the initial offset. Any suggestions for a solution? – Many thanks.
In the past I have made a few inverting op-amp circuits with gains of 10, 50 and 100, these have worked OK. One that had been working for 5 years had a copper track peeling so I tried to make a replacement. I can breadboard circuits that work but when I solder them up I have been getting erratic readings and the meter would not zero. The track did eventually break and I had no choice but move all the components to another part of the same board, in spite of the fact it had worked OK for 5 years it would not now work. The problem, I suppose, is thermocouples at the solder joints, but I wonder why I didn’t get this problem before. I have tried a few things to overcome this problem without success, the latest was to solder resistors and wires directly to the IC, cutting out the usual IC socket and using prototype board without copper pads or tracks. The meter fluctuates between zero and 1.2 mV initially. It does amplify 1 mV to around 100 mV but of course includes the initial offset. Any suggestions for a solution? – Many thanks.