From: D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent: Saturday, January 31, 1998 7:25 PM
To: Tesla List
Subject: Re: Current Limiting
Another resistive element that works good is a resistive grid stack used to
control large electric motors before all the SCR's came out. Sometimes you
can find them in large motor repair shops doing their duty as a boat anchor
hence you can get them for a very low price or scrap value. They do
dissipate a lot of heat so don't plan on using them in the summer in a warm
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-pupman-dot-com>
> Subject: Current Limiting
> Date: Saturday, January 31, 1998 1:39 PM
> From: Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
> Sent: Saturday, January 31, 1998 10:44 AM
> To: Tesla List
> Subject: Re: Current Limiting
> > So.. based on this idea.. and the fact that lightbulbs don't exactly
> > short things out, why not use lightbulbs as resistive ballast?
> > I am not exactly sure what the VA rating for a bulb is.. but for
> > grins sake, assume a 100W bulb is 100VA, paralleling 2 bulbs gives
> > you total power flow of 200VA, 3.. etc. [ for 220, use 2 110V bulbs in
> > series].
> You bet it will work. Of course, lightbulbs don't have constant
> which actually helps in this application. As the current increases, the
> resistance increases, which reduces the current, etc. This is a standard
> technique for stabilizing the amplitude of audio oscillators (cf.
> Hewlett-Packard designs from day one) and emitter ballast on bipolar
> Lightbulbs and their sockets ARE more expensive than surplus power
> resistors or stove elements though. And, they give off all that light, as
> Inductive ballasting (e.g. NST shunts) is nice because it limits the
> current without loss.