SEC 06: Measuring SRF without oscope

In this video I show a circuit that can be used to measure the spatial resonant frequency if you have a source of signals and a multimeter. Great for keeping experiments nice and cheap. The circuit was found to be pretty accurate (within 0.2MHz of oscilloscope)

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Science & Technology

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[min2oly]

any way you can turn your "smart" phone sideways instead of upright?

maybe a different app... most annoying

It takes away from the most gracious and excellent info you provide.

thanks for sharing - BTW

cheers,

Patrick

[rau369]

@min2oly Yeah it annoyed me a little too but I only noticed when it was uploaded and it took an hour and a half to upload, I wasn't doing it again. Turns out a 'smart' phone really might not be that smart lol Thanks for your comment, I'll ensure this doesn't happen anymore :)

[slider2732]

Does the yellow one have numbers on ? like 104 or 223 ? Tables of values are online easy enough, 104 being a .1uF (100000pF, 50V normally and 10% tolerance). The bigger the number at the end, the bigger the multiplier of capacitance.

Enjoyable instructional vid, thanks :)

[rau369]

@slider2732 The yellow capacitor has '1n2J 100' on the top of it.

[slider2732]

@rau369 hmm 102 is 1nF, 100 'should' be 100V, larger size than regular radio circuit caps. Often the multiplier is used instead of the decimal point. Here's a good page: kpsec. freeuk. com/components/capac. htm. Hope i'm helping.

[rau369]

@slider2732 Thank you for the link I'll check it out now. Your definitely helping :D

[rau369]

@KyleCarrington Sorry I knew there was something I missed. The brown ceramic was 100pF. I can't work out the size of the yellow one but I will say that ideally you'd want it to be small, the smaller it is the easier it gets charged and therefore the more accurate it'll be.

[KyleCarrington]

Thanks very much. So when you set your signal generator to 14.6 MHZ, you ended up with 15.x on the multimeter... and that was the peak ~mV readable? (Aside from the lower anamoly at 19.x mV) What choices in your capacitors have you made, and will that vary? Thanks very much.