Re: Inductance meter for BIST

On Mon, 08 Apr 2024 17:17:15 -0700, john larkin <jl@650pot.com> wrote:

I can build this into my new programmable inductor module, for
self-test. With a 1% cap, it should be plenty good. L range will be
750 mH down to maybe 10 mH, part of simulating solenoids and torque
motors and such.
>
If I add a switch to open R3 and run some current through R1, it can
measure series resistance too.
>
https://www.dropbox.com/scl/fi/tn8lpk38677ioylhdkget/P955_L-meter.jpg?rlkey=xynqyzfc2x020llr3a945c0td&raw=1
>
https://www.dropbox.com/scl/fi/gojlqxj23r4m57ke9jhui/Ind_Meter_1.asc?rlkey=if40kmtiz49gp62bacfvju3uv&dl=0

Most L-meters, the AADE sort, lie or don't work with big Ls.

This is better:

https://www.dropbox.com/scl/fi/9tex1slpnaqz4n2cbxp3n/Ind_Meter_Apr_9.jpg?rlkey=52vbyylc5ax48w54qdxm9r9cq&raw=1

Given a small uP, like the Rasp Pi thing, it could measure L and Rl
pretty easily. One could get compusive and math out the small
inductance measuring error from the inductor copper resistance.

I need repeatability more than accuracy, and don't have time to
explore this very deep, but it's interesting.

I've been buying shaftless torque motors off ebay, to understand them
electrically. We need to simulate a torque motor.