[sdiy] Analog Modeling, with a computer!

[Antti Huovilainen]

On Wed, 14 Sep 2005, Harry Bissell Jr wrote:

> I'd disagree (in part). Modeling a capacitor or
> resistor is unlikely to result in any change in

I meant that simulating the components _separately_ is not sensible. Of 
course the complete model should take into account all relevant 
nonidealities (finding them is the tricky part!).

To go back to my AD example, you cannot model capacitor, resistor and 
diode separately, as it is their interaction which produces the result. So 
you model the combination and arrive into a single non-linear differential 
equation that takes all relevant things into account (in this case the 
logarithmic V-I curve of the diode).

In this case it is (for the decay stage)
dV/dt = I/C
I = (V - Vd)/R = Is*exp(Vd/Vt)

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova