[Amps] Resonant choke measurment

[peter chadwick]

Another  method is to make a Hay's Bridge. Then you can apply AC via a transformer winding in series with the DC supply used to set the current through the choke. If the choke is around 20 ohms DC and you want to measure at 1 Amp, you'll need something a like a 20 ohm resistor capable of carryng an amp, and a suitable variable PSU - 50 volts at up to one amp. You do need a good sized capacitor across the PSU output, and by a few sums, you can work out the approximate values for the capacitor and resistors for the other bridge arms. So you need a PSU, a big electrolytic, a low voltage AC source, a high power resistor, two low power resistors and a selection of capacitors. Plus a scope, or at a pinch, a pair of headphones.
Plus the choke shouldn't be resonant at the ripple frequency, but a little  bit above the ripple frequency, so that it appears as a much bigger inductance. (Resonance is where the applied voltage and current are in phase, and the XL=XC is an approximation - usually, but not always, good enough.

73 and Season's greetings
Peter G3RZP