Looking for a switch...

Yes Ron, as williB indicated I would like to have power after the delay and stay on.

nerosrevenge said:

Ok I have prepared a schematic based on Dingo's suggestions (I have adjusted the voltage for now, the final circuit will be 9v) The file is attached.

Thoughts??

Steve.

Click to expand...

Ummm not quite.
See drawing below, quickly done in paint :roll:

When you press the button the relay will stay in, let go of the button the relay will still stay in until the cap discharges, that is your timer.
Flick the switch without pressing the button first and it is an instant boom fizzle ding of whatever you have connected to it.

The idea is, press the button and hold it in, flick the switch so it is closed (you are now armed), as soon as you let go of the button the countdown starts.

Thanks Dingo. I have a question. If I hook up the following circuit 3v+ to 1100 uF capacitor to LED to ground, the led lights for about 3 seconds and then goes out once the cap is full. So using the same idea, if I go 3v+ to the cap, then to the relay, then to ground, the realy should open until the cap is full. Is that correct? So then using and SPDT relay once the cap is full and the relay switches, that will complete the secondary circuit which basically the cap supplying power to the LED (which in turn should light) is that correct?

Thanks again!

Steve.

nerosrevenge said:

Thanks Dingo. I have a question. If I hook up the following circuit 3v+ to 1100 uF capacitor to LED to ground, the led lights for about 3 seconds and then goes out once the cap is full. So using the same idea, if I go 3v+ to the cap, then to the relay, then to ground, the realy should open until the cap is full. Is that correct? So then using and SPDT relay once the cap is full and the relay switches, that will complete the secondary circuit which basically the cap supplying power to the LED (which in turn should light) is that correct?

Thanks again!

Steve.

Click to expand...

Not sure what you are after here. Can you supply a circuit or discription of what you want to do?

Do you want the LED on while timing out?

I think I may have confused things with my last post. I as only trying to acertain if a relay would behave in a similar fasion to an led once the cap had fully charged.

Here is what I am after (for information sake I should mention that the LED at this point only represents the device I am trying to control using this circuit so the voltage has been adjusted from 9v to 3v for simplicity).

I want to depress a button, 3-7 seconds later (the timing is not crucial at this point) I want the LED to light.

I'm not sure I understand why it is the schematic I posted won't work. Can you explain?

Thanks,

Steve.

nerosrevenge said:

I think I may have confused things with my last post. I as only trying to acertain if a relay would behave in a similar fasion to an led once the cap had fully charged.

Here is what I am after (for information sake I should mention that the LED at this point only represents the device I am trying to control using this circuit so the voltage has been adjusted from 9v to 3v for simplicity).

I want to depress a button, 3-7 seconds later (the timing is not crucial at this point) I want the LED to light.

I'm not sure I understand why it is the schematic I posted won't work. Can you explain?

Thanks,

Steve.

Click to expand...

you have no power in the circuit with your LED...!!

The LED was never supposed to receive power from the battery directly.

I may have done the schematic incorrectly but the led was to be powered by the capacitor once it had stopped the power supply to the relay. Once the cap is full the relay would close again (theoreticaly) completing the LED circuit. I found that the capacitor once it is fully charged is able to light the LED (albeit on for a second but I think that is long enough for this application) I just haven't been able to find a suitable SPDT relay to run a test. The one I will ultimately need is 9v but none of the parts suppliers I have found have them in stock (even Radioshack). I have found several 12v SPDT relays, is it possible to increase the voltage before the relay from 9v to 12v??

:roll: This is getting complicated, I have to say thanks again for all of the help! You guys are great!

Steve.

i see what you are saying..
you were just using the LED to test the process..well you could still put a battery and a resistor and an led , on the right side of the circuit ,
for effect.. :lol:
a 12V relay would probably work , with 9 V..maybe.

I had no idea perhaps I'll pick up a 12v relay and give it a shot!

A led will not behave the same as a relay. Look for a reed relay it uses less current so the cap can keep it in longer, you can also use more than one cap just keep adding them on. 5v relays might be the way to go.

Anything more complex and you would be better off with 555 circuit williB posted.