[simpits-tech] RC Timer delay

[Ross Hutton]

 --- Stig Joergensen <stig.joergensen@clearsky.dk>
wrote: > Ross... please explain why....
> 
> As I see it, the resistance over the capisitator is
> pratical zero
> (remeber we are talking of DC not high frequency,
> where things start to
> shift :-) compared to the R1 value, And by applying
> the normal u=r*i
> rule; out should be aprox the strobe as long as it
> is held high....

Let's assume that before the strobe goes high the
voltage across the capacitor (Vc) is 0.

The moment the strobe goes high, Vc will still be 0.
Vout = Vstrobe - Vc = Vstrobe.

However, the capacitor immediately starts charging up
and after 5 time constants the voltage across the
capacitor will be within 1% of Vstrobe.
Vout = Vstrobe - Vc = 0

Vout will look something like this.

  *
  **
  * * 
  *   *
  *      *
***          * *

If your strobe is much shorter than a time constant
(and maybe in your case it is) then you won't see this
effect. 


=====
--
Ross

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