>I need a flip flop circuit with a one or two second memory
>after power has been removed and then turned back on.
>12 Vdc level to power two different circuits through transistors.
>It has to work like this :
>
>1. power applied / output 1 active
>2. power removed & re-applied before timeout / output 2 active
>3. power removed & re-applied after timeout / output 1 active

Hi Ed,

here is another but similar solution.

Use an RS flip flop, connect an RC network with a long time constant to the
SET pin and another one with a significant shorter time constant to the
RESET pin.
Now at initial power up both RC networks are discharged and start charging.
The SET pin however will be active for a longer time period than the RESET
pin and therefore output Q will be set high. (state 1)

On power drops shorter than your desired timeout, the network connected to
the RESET pin will be discharged but the one at the SET pin will still have
some charge, thus RESET will be active while SET will be not. Consequently
outout /Q will be set high. (state 2)

Germain

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