Also anotehr thing.
if hook up the coil to the battery I get an electo magnet. if I put a 50 ohm
resistance in series or even an higher resistance i get nothing. measured
the resistance of the coil. its 50 ohms. the resistance get very hot, but no
electro magnet.. why
ken
somewhere you state that the resistance of the coil is 50 ohms - well
if you put a 50 ohm in series with a 50 ohm coil half the voltage will
drop across the coil and half across the resistor. Your total current
with 100 ohms total resistance should be 120 milliamps and close to a
watt of power in the resistor - plenty to cause heating.
Your current with no resistor should be .24 with a power dissipation
of close to three watts in the coil causing it to heat (and depending
on its physical size and construction it may take awhile to heat
noticeably)
As for the electromagnet effect: with the resistor you cut the
current in half and you cut the voltage across the coil in half. You
drop the effective "ampere turns" by a factor of four so the magnet
should be 1/4 as strong as it was with no resistor.
It doesn't sound all that hard to do even with a 555 and a 3055
So something is obviously wrong . . .
What became of the 2 KHZ you were initially driving it with? Is/was
that a square wave? Is your coil very large?
I had a little 555 circuit driving a car ignition coil. The coil
resistance was ~3 ohms. I used a TIP 120 to drive the coil and it
worked reasonably well (made sparks). I forget the duty cycle, but
the frequency was adjustable and duty cycle fixed (I think - this was
several years ago)
This shouldn't be a big problem unless the inductance of the coil is
very high - and then it may be hard to pump any real energy into it at
2 KHZ with only 12 volts.
And when dealing with MOSFET's and inductors, like someone suggested,
it takes some savvy to protect the mosfet from the inductive kick to
keep from destroying them. You need a relatively high voltage part
and some high speed diodes or zeners to protect them - it would be a
good idea to read up on their characteristics first.