Re: How to make a slide choke ballast

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gregory Peters by way of Terry Fritz <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>

Quoting Tesla list <tesla-at-pupman-dot-com>:

Ted,

Actually, my particular choke wasn't very good for adjustment (hence 
my new C cored ballast). Despite having 100m of wire on it, it only 
had about 180 turns or so, because the diameter was 6". The 
inductance range I got was 2.5mH (no core) to about 20mH (core fully 
inserted). Obviously this ballast is no good for low power stuff as 
the lowest setting is about 38 amps. My core shows no sign of heating 
whatsoever, which leads me to think I could have used a much smaller 
one, which would have given me more turns and thus a greater 
adjustment range. 

If I was to make one again, I would use a smaller core (maybe 3-4"), 
more turns (like at least 300) and a centre tapped winding. I think 
the core should not heat up much, provided the rods are very thin and 
are well insulated. Open cores like this need alot more turns to get 
enough inductance, but they are pretty much impossible to saturate so 
a smaller core can be used (thus more turns per metre of wire). My 
new c core ballast has the same length of wire (actually a bit less) 
and has a range of 2.5mH to 0.25H!! The magnetic path is just that 
much more efficient. I could have wound more turns on the choke 
ballast, but I want to keep the resistance to a minimum, and I 
typically run at about 40 amps anyway. 


Cheers,

Greg.




> Original poster: "tesla by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>
> 
> Hi Team/Greg
> Interesting ideas
> Do you happen to know the L range of this setup you made ??
> Best
> Ted L in NZ
> ----- Original Message ----- 
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Tuesday, October 08, 2002 3:21 PM
> Subject: How to make a slide choke ballast
> Really big snip
> 
> >> 
> > If you want to make a slide choke ballast. I've had good
> success with 
> > the following:
> > 
> > 
> > 1. Wrap a coupla hundred turns around some PVC or thinwalled
> 
> 
> 
> 
> 
>