Re: Need a calculator that knows about coulombs
On Wednesday 23 December 2015 17:57:02 Gary Roach wrote:
> On 12/22/2015 06:02 PM, John Hasler wrote:
> > Gene Heskett writes:
> >> In this case, the size of a capacitor hooked to a square wave
> >> source, and I want to know how much charge is transfered for every
> >> full cycle of the input square wave.
> >
> > Zero assuming linear source and load impedence.
>
> And assuming the square wave is symetrical about zero.
plus or minus, at random, but within 10 u-secs of 50%.
> If I recall
> Q=CV where C is in farads, V in volts and Q is in coulombs. With R
> (circuit resistance) = zero. The Voltage on C will instantly be the
> supply voltage an Q=CV applies. In short, it is a steady state
> problem. If R is not zero then there is a charging time constant
> involved.
> But if the on period of the square wave is at least 5 times
> the time constant of the circuit, it's still a steady state problem.
> As I recall the TC = RC seconds. If the period of the wave is less
> than 5 times the TC then things get more complicated. Look up time
> constant in wikipedia will probably give you the answer. In any event,
> any scientific calculator will do the job.
I was hoping to get that sort of an answer, but my button pushing on a
TI-30X||S very rapidly degenerates into answers that are a factor of at
least 100 million from something useful. Sure t=rc, where c is in
farads and t is in seconds, but r in this case, in series with the
square wave input and Cp is an unknown.
I now have a test wire on the BoB that I was using to watch the signal
come and go on queue with a Ds101 pocket scope, essentially proving
my .hal chain of command works, but that was as far as I got today, I'd
found some 2000 grit wet-r-dry and seeing how that works to level up an
air brush laid but spotty finish on some poor mahogany, and busy putting
drops in the XYL's eyes breaks my chain of thought. She's had cataract
operations on both eyes in the last 10 days. First one is working
great, but the jury is still out on the 2nd one yet.
> Gary R.
Cheers, Gene Heskett
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