i have a transmitter that have 2 LEDs, one is a plain LED and the other is a super bright LED, if i press the button (normally open), the plain LED will light and will stay at that state unless i press the button again, the super bright LED on the other hand will just blink momentarily (due to the normally open switch)...i have latching circuit for the plain LED, but my problem is this...

I press momentarily the switch, LED1 turns on, and LED2 blinks then i will remove the battery or the Vcc from the circuit, and when i connect again the battery from the circuit, LED1 should be turn on immediately because this is the last state. And when i turn off the LED1 and remove the battery and then connect it again, LED1 should be off.

What circuit will i add to make kind of switching happens? Currently i have a pbno and a latching circuit in my transmitter. also, i can not use other type of switches because this a requirement.

thx!

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\"better to reign in hell, than to serve in heaven\"

 

The circuit cannot remember the last state if the battery is removed. It will start in a random state when the battery is re-connected. If you want it to remember the last state, you would need a non volitile memory.

Alternatively, you could have a "switch on reset" so it always starts in the same state.

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Len

 

'ljcox" + if need a solid state soln,(ofcourse with constraints) , u can use a large cap+higm imp: switch ckt to store a charge ,(like a long term volatile memory)

 

Yes, that would be a way to do it - provided that the quescent current drawn by the device is small. Otherwise the cap may discharge before the button is pressed.

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Len