Inductor question

Discussion in 'Electronic Basics' started by Jay, Jan 31, 2004.

1. JayGuest

Hi everyone. I have a question about inductors I hope someone can help
me with. It is for a physics lab and I am not too familiar with them.
I had imagined that they would have two leads like a resistor. However
I sent out for a variable inductor and received something that had
five leads - two on one side and three on the other. It also had two
larger ones on the side but I suspect they would be used for mounting
on a board. My question is about the function of the five leads here -
what exactly is what?

Thanks!
-J

2. Jacobe HazzardGuest

some combination of winding taps and coupled windings.

Measure the resistance between the leads with an ohmmeter, you will find
that some leads are connected by a low resistance, and by comparing the
resistances you should be able to determine the order (the pair with the
highest resistance between them are then ends of the winding, any other
wires are taps connected to the middle parts of the winding).

You may find that there are two separate windings, so that the resistance
between wires belonging to different windings is nearly infinite. This means
your inductor is also a transformer (since transformers are just coupled
inductors). It's also possible that some pins on the device aren't connected
to anything, or are connected to the case. Use your ohmmeter to figure this
out.

There should be a ferrite slug in the middle with screw taps in it, turn
this with a non-ferrous screwdriver to adjust the inductance of the windings
and/or the coupling between them.

3. JayGuest

Jacobe - thanks very much for the information!

Take Care -
- Jay