Instructables

Multimeter inductance meter?

I am building a Tesla coil with a fairly poor primary coil. The primary coil is a conical 12.5mH (theoretically) but when I measured it with my multimeter the inductance kept jumping and was only doing so within the range of .05mH - 2mH why is this can it not measure conical coils?

frollard3 years ago
I have a hunch that the multimeter is able to test in the range of 12.5 mH, it's designed for small discrete components -- what you're attempting to measure is an order of magnitude bigger and has its own capacitance problems to think of, let alone being an air core. I'd stick with the theoretical number for now.
The MadScientist (author)  frollard3 years ago
Would the air core be a problem because I tested the secondary coil and it was only 3mH below the theoretical calculation?
I'm going out on a limb here, but I just have a hunch the difference between expected, actual, and measured will be different for such a small inductance on the primary, where it will be significantly higher on the secondary...I really don't know, but I would guess the error would have a much larger impact on the measurement of a smaller value.
Got an oscilloscope ? If not, get one. You can't really examine your stuff without it.
The MadScientist (author)  steveastrouk3 years ago
Will a TV oscilloscope do I can make one of those?
They're usually only good to audio frequencies, you need Mhz.

Steve
The MadScientist (author)  steveastrouk3 years ago
My multimeter can do 20MHz.
What do you mean by "do" ? Measure 20Mhz or generate ?

Steve
The MadScientist (author)  steveastrouk3 years ago
Measure.
That'll be assuming quite high input signals I suspect.
The MadScientist (author)  steveastrouk3 years ago
High in what way?
Like it will want 1V amplitude input signals ? What does the meter's manual say ?
The MadScientist (author)  steveastrouk3 years ago
Minimum 1.5V max 250VAC.