Having 'shopped around for 'Air variable capacitance meter' , all I find is 'capacity meters ' or LCR types which seem to offer fixed value measurement.!
Even considered a Arduino project but.. where do I find a 'sketch'/programme, to build such a meter ?? Any help , much appreciated.

 

Welcome to AAC!

A variable capacitor would be checked the same way you'd check a fixed value capacitor. The only complication is that the former is variable and it would take multiple measurements if you wanted to verify min/max capacitance or linearity.

 

Hi Dennis thanks for the reply . I'm afraid I do not quite agree. Even the old Radio Shack LCR meter would give a continuous readout of the air insulated variable capacitors as used in antenna tuners, etc; as demonstrated on Youtube... !! Cheers

 

Hi Dennis thanks for the reply . I'm afraid I do not quite agree. Even the old Radio Shack LCR meter would give a continuous readout of the air insulated variable capacitors as used in antenna tuners, etc; as demonstrated on Youtube... !! Cheers

Get used to digital instruments, or build you own analogue.

555 based capacitance meter schematics aren't exactly rare online. Most integrate the output pulses to drive a moving coil movement, but you can improve accuracy by triggering a monostable that has constant current output.

 

You mention, building my own analogue circuit ,,! Many years ago I did exactly that , long before digital 'readout' ? just the old meter..
In my late nineties, just 'ain't got the same 'verve' or whatever you would like to call it... Guess I'm looking for an easier solution..
Have quite a number of old variable caps , the larger are ones somewhat easy to 'guesstimate' , , Yes I agree , one can have fun with old 555
If really necessary, I will have to 'fire-up' the old soldering iron , hi Thanks for your interest

 

You mention, building my own analogue circuit ,,! Many years ago I did exactly that , long before digital 'readout' ? just the old meter..
In my late nineties, just 'ain't got the same 'verve' or whatever you would like to call it... Guess I'm looking for an easier solution..
Have quite a number of old variable caps , the larger are ones somewhat easy to 'guesstimate' , , Yes I agree , one can have fun with old 555
If really necessary, I will have to 'fire-up' the old soldering iron , hi Thanks for your interest

There are off the shelf frequency to voltage chips for this type of thing - probably the LM2917 or something like that.

TI did the SN76810 tachometer chip, its long obsolete and the data sheet isn't easy to find either - but the internal schematic pretty much shows you how its done.