ON/OFF pulse switch???

Didnt know what to title this as, im looking for something that requires a single quick pulse to activate a switch.

once the switch has been activated i dont want it to consume any more power so a relay is out, looked at thyrister but they require a continuous current to stay on.

the switch is connected to a timer, every 3 hours it sends a pulse, this will activate the switch, the switch is a double throw, i.e it has 2 outputs

so as an example i need it to do the following,

3 hours elapsed, pulse, switches to device A
3 hours elapsed, pulse, switches to device B
3 hours elapsed, pulse, switches to device A


anyone any ideas???

555 and 4017 can fulfill you requirement.
You just use only Two channels of 4017, so that it can toggle one and other for each pulse.
But i am not sure about 3 hours time delay using 555 timer.

Hi cobra,

use the CMOS-version of the 555 timer circuit. You should be able to generate 1 pulse every three hours (better use a timer circuit and a binary counter, e.g. CD 4020 to keep the timing capacitor within small dimensions and timing more accurate).

Use a JK-Flip-Flop (CD4027) to switch on the loads alternating.

Boncuk

hi guys, thanks for the input, i have just looked at a couple of circuits that use the ICs you mentioned, they all use a relay for switching between side A and B.

this will consume too much of my power holding the relay coil for 3 hour periods.

ideally the 2 outputs from these ics should light leds, not a relay that toggles back and forth.

will keep looking and see what i can find

cheers again guys

cobra1 said:

this will consume too much of my power holding the relay coil for 3 hour periods.

Click to expand...

ideally the 2 outputs from these ics should light leds, not a relay that toggles back and forth.

Click to expand...

Sounds like a job for a **broken link removed**.