On Wed, 18 Mar 2015 17:40:06 +0000 (UTC), DecadentLinuxUserNumeroUno
wrote:

On Wed, 18 Mar 2015 10:30:44 -0700, John Larkin wrote:

On Wed, 18 Mar 2015 09:28:57 -0700, Jim Thompson
wrote:

Voltage-Controlled Capacitor Spice Model now on my website.

See VControlledCap.zip on the Device Models & Subcircuits Page.

Includes Library File (.LIB), LTspice Symbol (.ASY), and a JPEG showing
how it was developed.

...Jim Thompson

I don't have time to play with this just now, but one quick question:

Given that C is a variable capacitor, set C to 1F and charge it to 1
volt. Now change C to 0.5F. What is the new voltage?

How many 1 farad capacitors are you aware of?


In LT Spice, you can use any C value. 1F is the generic capacitor. I
usually normalize theoretical circuits to 1F, 1H, 1 ohm. [1]

In real life, Digikey will sell you 1F caps. Or 5000F caps. But not
variable 1F caps.


Oh and would not a 1F charged cap dump into a 0.5F cap and fully charge
it? If that answer is yes, then the voltage would be the same...
slightly less even, all elements considered.

You thought it would morph the EMF into something else?

I'd like to know if Jim's model conserves charge, or conserves energy,
or conserves voltage. Or whatever it does.


[1] I do find myself picking standard values, like 39nF instead of 40
nF, and worrying about leakage and stray capacitance and power
dissipation, when none of these matter in Spice.



--

John Larkin Highland Technology, Inc
picosecond timing precision measurement

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com