One shot upon power-up...

[Rescue1]

I would like to build a circuit that will give a single pulse after power-up.Problem is I would like it to be approx. 10 seconds after power-up.When the circuit is powered down,it will reset and the whole process will start over again upon power up.Thank you for the help....

 

[mozikluv]

timer

hi,

what you need is an astable circuit. check out my post last Jan. 14, 2004, you will the formula to use.

 

[Rescue1]

Thank you for the reply,and the great formulas... ...I am familiar with the 555,but what I want to do with this circuit might not have been written clearly by me.Upon power up,I would like a single pulse about 10 seconds after.Then the circuit would power down,or at least stop pulsing.Now a 555 can be set up for a single pulse,but how do I do it approx. 10 seconds after power up,as it would pulse again at some point.My thoughts were to use a cd 4017 counter on the 555 pulse,then set up the time interval so I could use one of the outputs of the 4017 approx. 10 seconds after power-up.The next output I can tie into a flip-flop,or latching relay to shut down the circuit,or pulsing.I think this setup will work,but I like to keep things simple,and feel this can be done by simpler means.Thank you for the help... :lol:

 

[panic mode]

did you think of two 555s?

 

[ljcox]

Power on reset

A Hex Schmitt Trigger such as the 40106 would be much simpler.
Design 2 RC timers in tandem. The first would time the 10 sec, the second 1 sec. Then use an AND gate to provide the 1 sec pulse.

Len

 

[Rescue1]

Both are some great ideas.How could you get the second 555 to just give one pulse though...

 

[Nigel Goodwin]

Both are some great ideas.How could you get the second 555 to just give one pulse though...

Wire it as a single shot monostable.

 

[Sebi]

Maybe this is a simple solution...