Lowest energy Timer circuit

[icap123]

HI people!, I'm looking for something like an auto-open-switch circuit, I mean I want to turn on the switch and the lamp light on approximately during 5 minutes and then the switch automatically open the circuit. I have make one circuit with lm555 monoestable and astable, its ok but I need something who dont need energy supply all the day like the lm555 monoestable or astable (or the one who stay in the market), I know its a very little current... buts all the day!!!, I am an ecologist, need a Timer with the lowest energy circuit for my radiant experiments. Maybe a solenoid? maybe a 555 with relay? or maybe you think doesn't exist something like that?...thanks in advance...
sorry if my post is in a wrong place, if so, I'll delete or relocate it.

[sucahyo]

That is difficult problem. If you are using relay, relay will consume at least 50mA up to 250mA when ON.

To reduce current consumption of a 555, use high resistor number (maybe in 100K range) and lower the capacitor value to compensate. Maybe you can run it with 20mA or so.

How about optocoupler? it should consume less power.

[Harvey]

The TLC series 555 is a low power version.

But your problem is a different problem than just getting a low power timer, you want your light to turn off after someone has left it on for 5 minutes. Then you want it to reset the next time they turn it on.



A time delay relay does just that. When the light is powered, the relay energizes and keeps itself on and the timer begins the countdown, at the end of the countdown, the relay disengages and severs the power to itself and the light.

In order to turn the light on again, all that is needed is a momentary connection to the relay coil, and the process repeats.

This way, no power is consumed when the light is off.