Analog Discovery Impedance Analyzer Bias Voltage

[@chris_lynch]

Great video. Im going to buy a AD3 soon and ill make your pcb. Im mainly interested in inductors. Is there a simple way to do the test with a bias current? Thanks

[@TheStuffMade]

Thanks, I believe you should be able to use a similar setup with a coupling capacitor, just with more current. Cheers, Jake

[@chris_lynch]

@@TheStuffMade I could probably use the coupling cap and one or more inductors to block the sine wave from the current source. I'll select the values based on the sweep frequency

[@TheStuffMade]

@@chris_lynch You're right about the extra inductor. I did a quick test using a 80uF coupling cap and a 400uH air core inductor between current source and the DUT, then measuring a surface mount cored 68uH inductor with up to 3A dc bias current. This seems to work just fine. I did add a couple of extra diodes across the inductors, just to be on the safe side. Cheers, Jake

[@chris_lynch]

@TheStuffMade great, thanks for testing it. I ordered an AD3 so I'll be able to play with it soon :). Good idea about the diode for back emf. Out of interest what did you use for the current source? I'm tempted to build a high current one. At the moment, im just using a bench supply and rheostat, but my bench supplies are prob too noisy for this purpose.

[@TheStuffMade]

@@chris_lynch No problem, I just used a linear bench supply as current source, that worked fine, but limited in max current available. For the inductor between current source and DUT, I used a large air core (speaker crossover type inductor) as it should be able to take a lot of current before saturating. For the diodes, I believe the silicon ones I used did have an effect on the measurement, probably some TVS diodes would be better suited. Cheers, Jake

[@wahng9552]

A fairly easy method to measure the relevant capacitance parameters with bias. Is there any way to obtain the board and software so I can try this out this method ?

[@xaledxaled418]

Is it possible to measure output impedance of a DC PSU using this board? Something like Cleverscope does: kzbin.info/www/bejne/qoSkfqmpnL6LjZI