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From: Jeroen Belleman <jeroen@nospam.please>
Newsgroups: sci.electronics.design
Subject: Re: Inductance meter for BIST
Date: Tue, 9 Apr 2024 17:36:28 +0200
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On 4/9/24 16:19, John Larkin wrote:
> 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.
> 
> 

What's R1 (1G to +5) for?

Are torque motors actually predominantly inductive? Just
because it has coils doesn't necessarily mean it is so.

Jeroen Belleman