5 second on timer

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Gr3mlin2008

New Member

• Feb 13, 2008

• #1

Hi, i was wondering if someone could help, i want to have a button that when pressed and held for 5secnds it outputs a -vdc, clamps to earth.
then if pressed again for 5 secnds it turns that output off again.
Any ideas?
cheers

edit: and maybe if possible does a quick output -vdc on a 2nd output. on a quick pulse will do. but thats not a biggie*

 

Hero999

Banned

• Feb 15, 2008

• #2

Why do you want to do this?

This would be easy with a PIC.

 

G

Gr3mlin2008

New Member

• Feb 15, 2008

• #3

I've been working on a little project, and i need a delay on the button before it activates the output.
That said my requirements have changed.
when some presses the button, it begins a 5-10 second count down, then at the end of the delay, a small -vdc pulse is all i need.
then if button 2 is pressed, 5 seconds later a small -vdc pulse is all i need.
So basically all i need is a 5second counter with a pulse to ground.

make sense?

 

fingaz

Member

• Feb 16, 2008

• #4

Hi,

Google for 'on after delay 555 schematic' there are a number of schematics available on the web. you could use 2 555 circuits to acheive what you want but you may have to play around with the R/C values to get thie timing delay you want.

 

G

Gr3mlin2008

New Member

• Feb 17, 2008

• #5

I've looked through 'Google' with no luck, it does have a lot of 555 timers, but i could not find one that only pulse to output once after the time delay has finished...

would this work, I have had a press on button, between the cap and its charging souce, so when the button was pressed it let the cap charge, then if the button was released it discharged the cap via a resistor on the NC and COM button terminals?
then that would give me my pulse on!? Right?

 

fingaz

Member

• Feb 17, 2008

• #6

I think you should be able to use an 'on after delay' and use a small (0.1uF) ceramic cap on the output so that you just get a small pulse. You may have to use a NPN transistor on the output to invert the output from a positive pulse to a negative one.

 

G

Gr3mlin2008

New Member

• Feb 17, 2008

• #7

fingaz said:

I think you should be able to use an 'on after delay' and use a small (0.1uF) ceramic cap on the output so that you just get a small pulse. You may have to use a NPN transistor on the output to invert the output from a positive pulse to a negative one.

Click to expand...

Ok, when you say, "I think you should be able to use an 'on after delay'" can you supply me a link, cos lastnight i spent 1hour googling 'on after delay' and alsorts of different things. trying to find a circuit diagram of which you speak. to no avail.
as for the npn transistor, that exactly my thoughts. but i still need to get the delay before turning on worked out!

thanks for the reply!

 

fingaz

Member

• Feb 17, 2008

• #8

Try looking here


near the bottom of the page is a '10 minute timer' schematic, there's also an explanation of the circuit. You'll have to change the values of the caps and resistors to reduce the timing cycle.