[A83] Re: OT: Clock with resistor and capacitor
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[A83] Re: OT: Clock with resistor and capacitor
Here is what I learned in school about RC-circuit's
If you want to know the voltage in the capacitor you can use this formula:
Uc = U max * (1-e`(t/tau) (That's minus time divided by tau)
If you want to put this in your calc as a function, you'd have to do this:
(for example say R = 10 ohm C = 2.5e`6 F Umax = 8 volt)
1 tau = R * C
= 10 * 2.5e`6 (minus 6)
= 1.25 e`5
function becomes : Y = 8 * (1-e``(X/2.5e`5)
You'd see that it graphs with a e-power.
Remember that it is said that after 5 tau the capacitor is full
Which would come down to
5*2.5e`5 = 1.25e`4
Type this in as Xmax and 8 as Ymax, and you should get a nice graph ;)
(Xmin = Ymin = 0)
This formula relates to when the capacitor is being loaded, when being
"unloaded" the 1- is being removed from the formula.
Hope this helps you
>From: Gavin Olson <gtolson@snet.net>
>Reply-To: assembly-83@lists.ticalc.org
>To: assembly-83@lists.ticalc.org
>Subject: [A83] Re: OT: Clock with resistor and capacitor
>Date: Tue, 09 Oct 2001 14:44:34 -0400
>
>
>At 05:01 PM 10/9/2001 +0200, you wrote:
>
> >A few posts ago, someone mentioned that the clock frequency in the
> >TI-83(+) was done with a resistor and a capacitor.
> >Can someone give me more info about it, since I need to have a simple
> >clock generator for a (+5V DC) cirquit I'm making.
>
>
>For a clock, a capacitor will fire on a predictable interval. There is a
>formula by which you can take capacitor value and voltage (an perhaps
>amperage) and get a clock frequency. The resistor is just there to fix the
>formula to the right clock given the other parts of the circuit. If you
>need help with electronics stuff, there are a number of good web sites, or
>the TI-H list.
>
>
>
>
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