Air Cored Inductor

[Fuse_Burner]

Cool, I'm glad I asked. This works for a tank coil as well?  I've been told that a tank coil presents no loss and creates no heat.

[ConKbot]

http://www.colomar.com/Shavano/inductor_info.html

Looks decent for putting in a desired inductance and spitting out turns/dimensions that should work. Youre gonna need a lot of turns for a 1mH inductor

[AlfBaz]

if you have something to measure inductance, get yourself some thick copper enamelled wire and wind it onto a half inch whitworth bolt. 10 -15 turns ought to get you close, then unscrew the bolt from the wound wire

Surely this is too low for 220uH or 1mH with an air core?

To be honest, I don't know.

If that formula I posted is remotely accurate then a 1/2" BSW thread is 12TPI so diameter, d = 0.5" (Although I believe its the total outside diameter including the wire), over an inch turns, n = 12 and the length of the coil, l = 1" so
0.5^2 * 12 ^2 / (18 * 0.5 + 40 * 1) = 0.735uH 

Brain fart, thought another .3u would make it to 1m 

[Mar]

if u need 1 mh aircore you will have to do handreds of turns ...
i made 1 mh inductance with ferrite toroid core  got from old ATX power supply ( i though its AL=92 )  .. with only  114 turn about 4 meters from 0.7mm wire diameter ...

[ConKbot]

if u need 1 mh aircore you will have to do handreds of turns ...
i made 1 mh inductance with ferrite toroid core  got from old ATX power supply ( i though its AL=92 )  .. with only  114 turn about 4 meters from 0.7mm wire diameter ...

You have to mind your saturation though if you are using a core. For the desulfator, the L3 inductor, its keeping the pulses/ringing of the desulfator from affecting the charger. So it needs to maintain its inductance under the full charge current.  The ATX one will work fine for smaller charge currents, but an air core will work fine until you burn the insulation. 

Also, if you want to buy instead of make, parts-express sells air-core inductors for decent prices. Meant for crossovers in stereos

http://www.parts-express.com/term/1.0mh?srch=1.0mH