Math help...

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

Original poster: "Luc by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ludev-at-videotron.ca>


Hi guy

I presently build a DC power supply for coil. I want to be able
to use it for big coil but mostly for small one, you could see
the circuit at:
http://pages.infinit-dot-net/luc2/ps_mot_3.gif

Some of you will tell me to use a variarc for power control; I
have some but I choose to use variable water resistor for many reason.

Any way I need to have an equation to know at different value of
power how much power will be dissipated in the variable resistor
and the primary circuit ( power in the V. resistance + power in
the primary circuit ), I already know some equation : capacitive
energy J=C*V^2/2, ohm law V=I*R, P=V*I, P-V^2/R, transient
V-(Vf-Vi)*e^-T/RC, but can't merge them in a big equation...:-((.

What I want to have is an equation where variable are PS voltage,
cap value, break rate, value of my variable resistor, one of the
unknown will be the power dissipated in the variable resistance
when the SG conducted, it could be estimated like a short of the
PS across the V. resistance for the time the gap conduct, but an
approximation will do the job. The output of the equation will be
the power use in primary circuit and power dissipated in the
variable resistor.

If one of you could help me with that or make a small excel file
I'll be eternally thankful ;-) .

Cheers,

Luc Benard

*This post and an other one was send friday at 1:00 PM but both
never make it to the list...???