Measuring inductance with just two transistors

Using a 2 transistor RF oscillator to measure inductors as used in RF circuits. It's super simple but it works.
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[@acmefixer1]

I've had perplexing problems measuring inductors. I measured a 100 uH choke on an LC Meter IIb from AADE and it measured 78 uH. I tried it on an LC Meter from China and it measured 82 uH. I corresponded with the guy I bought them from and he had the same problem, all his measured well below 100 uH even on a HP meter. The only explanation he had was that different LC meters measure at different frequencies and give different values. Some meters use frequency as low as 1 kHz. Some meters use a square wave so the reading may be different. With this simple meter, I think it would be less prone to inaccuracy because the frequency is more in the range of what the inductor will be used for. And with a switch, the range could be changed. The SRF - self resonant frequency, can greatly influence the measurement, and some meters don't take that into account. Thanks for the informative video.

[@GeorgeGeorge-xj2bc]

I am testing and simulating various circuits in an effort to make my own and have different readings to an old Thandar TC200 LCR,metering 'em with circuit and frequency meter and different results in LTspice that found the dc resistor of the coil alters the signal period and finally the reading results.

[@cthoadmin7458]

Yes Peter, please do more vids. Like this. Nice to try to get back to the way amateur radio was before commercially available equipment. Reuse, adapt, tinker, build, explore, learn. I’d like to see radios from junk, or even radios from nothing, like detectors made from a piece of coal, variable capacitors made from plastic coffee cups and coke cans. Thanks for your contribution to,amateur radio over the years Peter.

[@paulepruss]

New amature here Peter and I would very much like to see more "old school" projects and experimentation from you. I've enjoyed everything that you have posted here, I have your ebooks and I'm of the opinion that you are one of the most down to earth and hands-on operators offering instruction "out there". I mentioned you to my local club and the fellow chuckled and commented on a video where you ran a counterpoise (?) down your leg, into the water as you waded in the shallows on the beach. "Good up to 5 watts, then it starts to tingle" (or something like that) - epic! Many thanks.

[@XxzemexX]

Most intriguing video I’ve watched in a long time. I binge KZbin 24/7, FYI. Most vids are bilingual, one size fits all, kind of answers. This video tho, total electricity enlightenment. I vote more vids. Thank you

[@chronobot2001]

Love it... Do more old school stuff. You are an inspiration.

[@chronobot2001]

More primitive test equipment... Yes please! Love your channel. Keep up the good work.

[@jacobfarnes8572]

Thank you Peter. I really appreciate you taking the time to document simpler devices & ways to measure things. You've got me thinking of how to test things without needing expensive equipment.

[@FishingHam]

Peter awesome video! Yes Please make more of these videos!

[@Berghiker]

Just what I'm looking for. That's just perfect! Thanks.

[@khalidtarawneh2289]

great info, what I like most about Ham Radio is it allows you to learn almost everyday, this has been very informative and well detailed Peter, thnx FER the info 73 from JY

[@YellowsourceOrg]

Yes! please. More of this. Thank you so much.

[@josephhager1933]

I would love to see more videos like this thank you for sharing.

[@frankjames264]

This inspired me to build something similar! Thanks Peter!

[@scienceappliedtotheunivers9871]

Great video, more please. I'm building out my lab.

[@MoTown44240]

Yes, of course. I am pushing building equipment rather than buying in my CW/QRP SIG (special interest group) of my local Amateur Radio Club. Of the new entrants to this hobby many are buying rather than building their equipment. It was your video and magazine article that inspired me to build a straight Morse key and I passed that on to the members of my SIG. We had a fun time that kit. One of the members is knowledgeable in building circuits and this month we are assembling CPO's (code practice oscillator). I don't need one but all the members do as they struggle to become proficient with CW. I'd rather build something that you've designed, built, and used rather than ordering a kit from China or elsewhere. KB8AMZ

[@MiscDotGeek]

Yes Peter, this was very informative! More! :)

[@guillermosempron5776]

Just BRILLIANT.

[@byAlmad]

Hi Peter...Homebrew with knowledge is better than a commercial one, due the challenge of it own built-in and good result ...Best 73. PU2SKA

[@ahmadhasan8607]

very interesting and helpful. thanks a lot.

[@WalterFox]

Very interesting and fun!

[@supyrow]

well done!

[@wasteoink8376]

Wow I have an LCR meter but it seem it doesn't like small inductors, your circuit seems easy to reproduce thanks

[@nasian4641]

Excellent

[@maur210]

G'day Peter, I just put one of these together and it works great. Its going to come in handy around my component junk box. Thanks for sharing. Keep up the great work. VK6HLY

[@tdumnxy]

Very interesting - more of the same would be appreciated.

[@magozander]

Thanks exellent

[@kevinsvanlife1259]

Very interesting Peter yes do more like this helps keep people on there toes. Thanks for your videos. Kevin Vk7Hkn

[@WI9LL]

I would love to see more videos like this! I want to build one of these testers. Do you have a printable copy of that schematic?( if not I can grab it out of the video)

[@vk3ye]

Only have the one on the screen unfortunately.

[@michaelpetrou2014]

Can you use any other transistors from jay car?

[@noisyaudio]

Picture is a bit dark. There's a similar circuit out there based on a LM311 comparator which let's L and C values to be measured. Thanks Peter

[@albertmorris4889]

Thanks Peter. There really does need to be more simple, repeatable & useful "Back to the Basics".

[@iceberg789]

thumbs up !

[@MauriatOttolink]

Simple additional connection could add yet another function..Xtal activity test oscillator.

[@josealfredoalcoviadebarcel4633]

Thanks Peter. Go ahead with your work on elemetary measuring technics. PY3HF

[@bundylovess]

Yes please

[@bullthrush]

Yes on primitive test equipment.

[@DonDegidio]

Hi Peter, Show video of more of your simple testers. 73 WB3BJU

[@andrzejpl9897]

👍

[@shobhityadav9019]

Sir namaste Sir how you calculate total capacitance of tank circuit.

[@vk3ye]

Find the tank circuit's resonant frequency with a known inductance. Then calculate the capacitance from the formula. A dip oscllator (or these days a Nano VNA) can do that.

[@shobhityadav9019]

Thank u so much sir for answering my question.🙏

[@jeetenderkakkar7570]

Hello sir What is inductance of two transistor

[@vk3ye]

I recommend this book which explains basic electronic theory. www.amazon.com/Radio-Theory-Handbook-Beginner-Advanced-ebook/dp/B083JHVK7P

[@peterbatka2402]

Better view on schematic: easyeda.com/batkapetko/nh-meter

[@amirassem-4668]

Thanks man you are the best!