A
Anthony Fremont
- Jan 1, 1970
- 0
I've been playing around with LTSpice and I'm ready to start soldering.
[I'm a hobbyist, not an EE student, so I can actually solder ;-)] The
circuitry is simple, but I need a logic level MOSFET (N channel) that
can take a Vds of at least 400V and 20-30A, though I won't be putting
that much current thru it for any amount of time (only around 5-6A avg).
The circuit is a fairly simple configuration with the MOSFET switching a
330uH inductor (wound it myself) to ground via a PWM signal. At the
junction of the inductor and the MOSFET I'll have a fast recovery diode
(the NTE substitute for MUR460) passing the high voltage peaks to a 400V
820uF cap. The plan here is to build up as much as 350V on the cap and
then dump that thru an electromagnet coil in order to provide some
impetus to a ball bearing. The initial circuit will have only one coil,
but I plan to add more stages later (if I survive) and control the whole
thing from a PIC. A simple voltage divider at the capacitor will
provide the feedback to the PIC so that it will know the cap is charged
to the wanted value. After looking at the LTSpice plots, I've decided
to add another fast diode between the inductor and the MOSFET to stop
those nasty negative currents that apparently flow thru the body diode
of the MOSFET after it turns off.
Fairchild makes a nice part (FDH44N50), but I'd like something more
locally obtainable like maybe an NTE part. Any recommendations on a
suitable SCR for dumping the 50J of current in about 10 milliseconds
would also be appreciated.
Thanks
[I'm a hobbyist, not an EE student, so I can actually solder ;-)] The
circuitry is simple, but I need a logic level MOSFET (N channel) that
can take a Vds of at least 400V and 20-30A, though I won't be putting
that much current thru it for any amount of time (only around 5-6A avg).
The circuit is a fairly simple configuration with the MOSFET switching a
330uH inductor (wound it myself) to ground via a PWM signal. At the
junction of the inductor and the MOSFET I'll have a fast recovery diode
(the NTE substitute for MUR460) passing the high voltage peaks to a 400V
820uF cap. The plan here is to build up as much as 350V on the cap and
then dump that thru an electromagnet coil in order to provide some
impetus to a ball bearing. The initial circuit will have only one coil,
but I plan to add more stages later (if I survive) and control the whole
thing from a PIC. A simple voltage divider at the capacitor will
provide the feedback to the PIC so that it will know the cap is charged
to the wanted value. After looking at the LTSpice plots, I've decided
to add another fast diode between the inductor and the MOSFET to stop
those nasty negative currents that apparently flow thru the body diode
of the MOSFET after it turns off.
Fairchild makes a nice part (FDH44N50), but I'd like something more
locally obtainable like maybe an NTE part. Any recommendations on a
suitable SCR for dumping the 50J of current in about 10 milliseconds
would also be appreciated.
Thanks