Re: Chart Recorder and Its Replacement

Pax Electronica

I did some testing on the terminals that supposedly provide the START signal. It turns out to be just a relay that closes when the recording starts and opens again when the scan is finished. The resistance goes from infinity to zero at START and goes infinity again at STOP, at least in theory. In reality, the instrument has other stepper motors going on and off. When that happens, the relay seems to be unable to hold down and goes open momentarily. The interruption is short enough so that a small capacitance could solve the problem, but is that what we supposed to do? Or is it an indication of some other problems, such as power supply going weak?

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