Help Needed

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Posts: 1
Joined: Thu Aug 01, 2013 6:25 pm

Help Needed

Post by Robkelly » Thu Aug 01, 2013 6:32 pm

I must first give my apologies for asking a basic question......I am new to the building of circuits.

Well what I'm after is a circuit that has a rocker switch for turning on one LED and some sort of timer relay to turn off the LED after a few minutes......also the circuit needs to run off 9 volt battery.

Many Thanks For Any Help


Posts: 170
Joined: Mon Jun 10, 2013 7:42 pm

Re: Help Needed

Post by Pauldf » Sat Aug 03, 2013 3:36 pm

You could use a latching relay and a timer relay, use a N/O (normally open) push button to set the latch and a N/C (normally closed) push button to reset it.
The latching relay lights up the LED and arms the timer. When the timer expires it's N/C contact will go open and reset the latching relay.
Then when nothing is running your batteries don't go flat.

Posts: 432
Joined: Mon May 20, 2013 2:45 pm

Re: Help Needed

Post by piratepaul » Fri Aug 16, 2013 1:20 pm

I kind of agree roughly with Pauldf ... momentary switches or just one switch (touch button) not a rocker. What sort of timer ... 555? is there a max time limit on A 555? I dont see why there should be other than if you charge a giant cap at uuA the losses might be more than uuA so it never charges... theoreticaly it could take years to charge.
I will build this circuit when I have time... dont know when that will be though.


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