Thanks for replies.
I need this to force a hard reset on some telematics equipment. The devices do have built-in timers that can be used for a variety of events, including a system reset. However in practice they fail after a couple of months. This is why we need to have a completely independent timer that we can rely on to do its job. Like I say it would be permanently connected to 5 volts, so would need to start timing on power-up. Also after its 2 second 'on' period, restart again. The 24 hours isnt critical, just an ideal figure, once a day. If this fluctuated and became 22 hours or 26 hours, or a mixture it wouldnt ever be a problem. Neither is the 'on' time 2-5 seconds is fine.
Thanks again.
Chris