Hi
I have a crossover to repair that requries a 3.3mH inductor. Can I put a 3.0mH plus a 0.3mH in series to make the 3.3mH total?
If yes, do they need to be arranged in any specific orientation to each other?
Can I mix an iron core and air core together?
Thanks.
I have a crossover to repair that requries a 3.3mH inductor. Can I put a 3.0mH plus a 0.3mH in series to make the 3.3mH total?
If yes, do they need to be arranged in any specific orientation to each other?
Can I mix an iron core and air core together?
Thanks.
Yes, the series connection will provide the wanted inductance. Orientation of the coils is necessary to prevent the flux lines cancelling. This implies separation and placing one coil at a right angle to the other. It might be easier to add turns to the 3mH iron cored inductor , however you will need a LCR meter to do this with reasonable accuracy.
simple impedance meter
You can measure the impedance of the Inductor if you have a multimeter wwith AC range of 2000mV and a 1% resistor of 10 ohm at least 0.25W
soundcard --> amp/red --> 3mH --> 10 ohms --> amp/black
turn volume control of amp down all the way.
set soundcard to Generator and put out a 40Hz sine of 0dB
measure AC across the resistor
turn the volume of the amp slowly up to 1000mV meter reading
now increase the frequency of the generator and see the meter showing less and less.
read the frequency at 500mV
a 3.0mH coil should read 916Hz, a 3.3mH 835Hz
You can measure the impedance of the Inductor if you have a multimeter wwith AC range of 2000mV and a 1% resistor of 10 ohm at least 0.25W
soundcard --> amp/red --> 3mH --> 10 ohms --> amp/black
turn volume control of amp down all the way.
set soundcard to Generator and put out a 40Hz sine of 0dB
measure AC across the resistor
turn the volume of the amp slowly up to 1000mV meter reading
now increase the frequency of the generator and see the meter showing less and less.
read the frequency at 500mV
a 3.0mH coil should read 916Hz, a 3.3mH 835Hz
If the inductor has DC resistance the frequency value is increased by Rdc/10 ohm, so for 3mH 1ohm we should get 1kHz.
There is a smarter way of increasing inductance, namely to add some magnet wire to your 3mH inductor and call it a day. You will need much less of wire than what's being put in a separate air core inductor.
Maybe if you have separate inductors, but not for the "same" inductor. I don't think this is a good idea when you're trying to produce a larger inductance. If you think about it, you could increase the L by adding more windings to the first coil, and obviously you'd only do that in the same coaxial winding direction.
As 3.3 mH is a standard E12 value, fiddling around with some more inductor or wire only might be necessary if the 3 mH inductor is readily on hands and needs to be replaced *imho*.
Best regards!
Best regards!