need help timing a simple circuit

[xanth]

Hi all, Great site, it's taken me a bit of time finding a good helpful forum like this. I'm trying to make a circuit that outputs +5VDC once every 5 mins from a +9VDC source (9v battery). I have the 5V power supply circuit but need a little help in the timing part of the output please. Not sure what to use for it, trying to keep it simple and cheap as possible. The timing could be below 5 mins but probably won't need any longer. Hope I've included enough info and I really appreciate any help.

 

[melone]

Try taking a look at the LM555 timer. The app notes can be found at

http://www.national.com.

Good luck and keep us posted!

 

[nbucska]

What is the tolerance and the duration of the 5V pulse?
(or what is it used for ?) <nbucska@pcperipherals.com>

 

[xanth]

It's going to be used for a keystroke on a keyboard, although I'm not sure what my friend wants to hook it to, possibly directly to the keyboard, or another contraption he has in mind. It will be a mechanical macro in a sense. So the pulse can be fairly brief I assume. I'm going to find out more from him as soon as possible and am looking through my school books on 555 timers right now. Thanks again for the help, I have a bachelor degree in electronics engineering but never applied myself with the knowledge after school beyond messing with computers and it's been a few years so a bit has left my mind.

 

[nbucska]

If it is not intended for production I suggest using 556 -- or two 555-s -- one for oscillator, the other to make
an adjustable pulse with ( monostable )

If driving solenoid, connect a diode antiparallel to protect
the electronics from the turn-off spike which may be HUGE.
<nbucska@pcperipherals.com>

 

[electricuwe]

Since you are going to operate the circuit from a battery I would recommend to use the CMOS version of the timer, LMC555, also available from National Semiconductor.