At 01:01 PM 12/10/2006, you wrote:
>Reference
>http://www.4qdtec.com/mvibs.html.
>
>I have been pondering how does the author claims the
>period for each state in the multivibrator comes to
>0.69CR. So for the entire cycle for on - off
>
>f = 1/T. Which is understandable.
>T = t1 + t2
>
>t1 = 0.69CR
>t2 = 0.69CR....... I have no clue how the author comes
>out which this magic value. Shouldn't it be 5CR
>instead of 0.69CR? Not sure here....
>
>Thanks,
>John

We know from calculus that charging a capacitor from 0 to V0,
v(t) = V0*(1-exp(-t/tau)) where tau = RC

if v(t) = 0.5 V0, t = -ln(0.5) = ln(2) = 0.693...

I'll leave it to you to figure out why it's ~0.5 of the charging voltage...

>Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com




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