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When I unplugged my 20 year old chest freezer, my electric bill dropped $60!

A resistor in the emitter will measure IC+IB. You can subtract IB with an op amp. Putting a resistor in the collector circuit would be difficult, you would need a common mode canceling circuit.

I agree that microcontrollers are the way of the future, but it is an analog world and you have to know how to do the interface. I have been doing analog design for 40+ years and am just beginning to learn how to use uCs.

You can get cores to operate above 100kHz, so heating at 20 kHz should not be a problem. Have you visited the Magnetics website? www.mag-inc.com

what do you want to do with it?

I have seen a mag amp regulated power supply, the only semiconductors in it were diodes. It is too expensive for most applications, except military.

My battery charger has a switch for nicad or nhmi, I don't know what the difference is.

You have 6vac filament voltage but is the filament lighted? You should see a light at the socket end of the tube.

Measure the forward and reverse resistance. The forward resistance will be low, under 1K, depending on the meter type and sensitivity. The reverse resistance should be open circuit unles you have a very sensitive meter.

A Johnson counter, divide by 4, has outputs that are 90 degrees. You could switch between them.

There are circuits that use a capacitor to simulate an inductor and vice-versa. Is that what you mean by "impedance converter"?

A 3 1/2 digit ohmmeter only costs a few bucks, why bother making your own?

I have use this equation for solonoid coils with good success: L (microhenries) = ((n^2)*r^2)/(9*r + 10*l) n = number of turns r = radius of coil (1/2 diameter) l = length of winding<p>Keep in mind that the leads of the coil are also part of the inductance which is not included in the equation!

You will need a multimeter. Use a 24 volt transformer for a voltage source. Connect the inductor in series with a variable resistor across the voltage source. Adjust the resistor until the voltage across the inductor is equal to the voltage across the resistor. Measure the resistor, now calculate th...

Why do you want to do that?