Hi everyone, I have an ancient Heathkit 10-12U oscilloscope,full of valves (tubes) and great for airing laundry. It seems to be only AC coupled; i.e. connecting a steady DC source produces a brief jump of the trace. If I connect a source of pulsed DC which peaks at 9V, how do I interpret & calibrate the trace? Pulse generator is a 555 timer as astable. Viva valves, John.
look on the input line, or some where around it. you should have a switch that saids DC/AC input.
John Marsh wrote:
Thanks for your reply Jamie;there is no such switch on this oscilloscope. It is very old.
Oscilloscopes of that general design were not calibrated at all. About all you can do is apply a known signal and use that as the calibration standard.
Yes, most inexpensive scopes were also AC coupled. The "zero" will be a line through the waveform with equal area above it and below it. Even this will be in error if the waveform you are viewing contains a DC component or contains very low frequencies
You adjust the calibrate (if it has one) until the trace has 9 vertical divisions on the graticule (if it has one).
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