Path: ...!news.misty.com!weretis.net!feeder6.news.weretis.net!usenet.blueworldhosting.com!diablo1.usenet.blueworldhosting.com!feeder.usenetexpress.com!tr2.iad1.usenetexpress.com!69.80.99.27.MISMATCH!local-2.nntp.ord.giganews.com!nntp.supernews.com!news.supernews.com.POSTED!not-for-mail NNTP-Posting-Date: Tue, 09 Apr 2024 14:21:10 +0000 From: John Larkin Newsgroups: sci.electronics.design Subject: Re: Inductance meter for BIST Date: Tue, 09 Apr 2024 07:19:26 -0700 Organization: Highland Tech Reply-To: xx@yy.com Message-ID: References: X-Newsreader: Forte Agent 3.1/32.783 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 31 X-Trace: sv3-F6PWT0c9IYe1yZHGDWksIB79QWMFAX8F+zUypC00eGDvP0SM7ynTXN71CusbJWQ/8KOVkPg5xuHmbpp!uAClaazDv+55c5YpsN/F0FRm/HDlBxNz1mhui/hp5xKJgOcbKnRZCYuaO7vDf07uGRaUjWNkSZbK!McwHCQ== X-Complaints-To: www.supernews.com/docs/abuse.html X-DMCA-Complaints-To: www.supernews.com/docs/dmca.html X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.40 Bytes: 2607 On Mon, 08 Apr 2024 17:17:15 -0700, john larkin 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.