Hey Dave

Thanks. Its gunna be a busy busy weekend.  ;]

Thanks Luc.   ;]

Im just full of energy today, dunno why.  ;]   Tonight im going to wrap 20 wires around me and see what output I get.  lol  ;]

Ok  back to worky   be back later.

Magfi   ;]

Can anyone tell me the best glue to use for coils of Litz wire?   I was thinking of using my hot glue gun but remembered that heat may melt the coating on the wire, although not as hot as soldering iron?  Hot glue is fast but not sure it will even hold the wires.      Or is it best to just use tape? 

Thanks

Bill

Hi Coradelelecktro

depends on cap uf value hwo many volts you will have in it from the backemf/recoil of the motor/drive coils - in say 5uf cap I will get near instanlty 200V from 12V input to my drieve coils and wait awhile and it climbs and climbs up too 300V or higher - those recoil spikes strech way off scope...
go with say 2000uf for you collector/recovery cap then at 12V you might only get instantly 15V or 20V somethign like that....
also if it lurches draw of motor up a bit when it fills cap is somethign to consider - you can only go with "so big" of a cap, and it will lurch draw up...smaller sizes dont do anything so find best cap size...

alternative is to "switch-out" backemf/recoil...put a swtihc on the AC leg of a FWBR or one side of single diode if you want, then you time the switch to turn ON during the period when the recoil spikes shoot out backwards - whihc would be at motor-coil's input switch turn-off...this makes thingks way different  - now "active" rather than "static" recovery....sometimes I can get dramatic speed-up of motor when backemf comes out doing a swtihc out circuit with the backemf.
Look for about a 5 degree delay to the backemf/recoil switch as compared to the motor coil swithcing itself...probalby a bit of "overlap" too - ther will be sweet spot according to rpms and load etc... its very precise when you do a swtich-out of backemf to get a speed up.

check out powering your motor coils with mosfets that are hooked bidirectional in that their gates and source leads connect and the swtihcing happens between the two drains now.
Put FWBR AC legs across the tow drains and DC into cap and you will get huge backemf power happenieng....mosfets only go "one way" you might be missing half of the power to be had.

Big thing about the bakcemf/recoil inot caps, is when you hit load with it you better have that cap DISCONNECTED from the coils they are collecing from or it all backs up makes big amps surge to the input, but if it is disconnected you get nothing at all and output to load is invisible to input.

Hey E2matrix

your calculations crack me up.

if you want to know how to calculate cap discharge here it is:

the Farads of the capacitor / 2

Multiplied by:

(high point of voltage in cap before cap discharge SQUARED
MINUS the low point of voltage in cap after discharge SQUARED)

Then all this multiplied by the RATE per second of cap discharge events...
not too hard eh

Quote from: maw2432 on June 30, 2011, 01:58:00 PM
Can anyone tell me the best glue to use for coils of Litz wire?   I was thinking of using my hot glue gun but remembered that heat may melt the coating on the wire, although not as hot as soldering iron?  Hot glue is fast but not sure it will even hold the wires.      Or is it best to just use tape? 

Thanks

Bill

Hi Bill

90 degrees C is the max I have found for hot glue guns

Polyurethane varnish is what I have used to make permanent coils. Tape is ok for temporary.