Help needed on Simple Timer Issue - Timer not correct due to Caps not discharged

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venkir

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All,

please help me on the below.

I'm using simple timer 2.5 seconds using Transistor and Caps.

As Caps discharged takes more time via bleeder resistance, the timer is incorrect on successive tries.

how can I momentarily short the caps and discharge either after switch of main voltage supply or during power on.

the circuit I try is very basic as in the link **broken link removed**


please help me and advice any change of or new circuit

thanks in advance.
 

That method isn't particularly reliable but keeping it simple, the easiest solution is to use a change-over switch instead of a press-to-make push button. Wire it so that when the button is released you connect a low value resistor (~47 Ohms) across the capacitor to give it a higher discharge current. Do not simply short the capacitor out as the spark will damage the switch contacts.

Brian.
 

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