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RE: Secondary coil forms and winding jigs
Sure I'd like to see the schematic.
Marius.
snip
""Terry, Reinhard, ALL
I've been using a winding jig consisting of a 12VDC windshield wiper
motor powered at 18V through a 60V -at- 75A Power FET PWM'd by a 555.
I've wound coils up to 24"OD and 3 feet long with no overloading.
The windshield wiper motor drives a 3/8" all-thread shaft supported
at both ends by 3/8" bulkhead bearing assemblies. The "tailstock"
bearing end is moveable on a wooden track and locked down with bolt and
wingnut.
The coils have a fiberglass top and bottom assembled with a 3/8"
tapped hole concentric with coilform. Thread shaft up coil with
VSD portable drill, and lock at both ends with 3/8 nuts. I place
a spring loaded wire carrier 15'+ behind winder, and manually control
wire feed using leather gloves (protect those fingers!!!). A slight
negative rake (5-10 degrees) will allow perfect close winding. The
motor comes with two speeds (low / fast), I wired a DPDT switch to allow
for motor reversal, and PWM allows speed from 0.5% (motor squeals, but
does not rotate), to 100% (about 2 turns/sec) in "high gear". I
included a turn counter triggered by a through beam photoeye to a 12VDC
mechanical counter with reset.
I can easily wind a 800 turn coil in less than 10 minutes, not including
coil setup time which is required anyway. The FET's are fused at 10A
against motor lockup, and have successfully blown without destroying the
FET's. Total cost out of pocket <$50 and about 3 weeks to wire and
assemble; and worth every dime. I have run circuit 3 days non stop
while curing polyurtheane on coil form, and the motor was the only
component showing evidence of heating. Windshield wiper motors are
cheap (less than <$20) in most locations, and are very powerful for
their size. I have schematic around here somewhere, may draw up in
Excel and have available if interested.
Regards
DAVE SHARPE, TCBOR
""