I have made a nifty timer for my wife's new knee rehab exercises. She often forgets to turn it off, so I have programmed it to cry (beep slowly) if it has no activity for 1 min.
But I think it would be better to rig an automatic turn off. I have tried with a transistor wired to both 5v plus and neg. so that a pin output to the base shoud keep it on for a defined term after a button starts the circuit. All attempts fail to turn it on or else to turn it off.
The unit is battery operated, so I don't want to use a relay. I have the circuit down to about 6ma, and don't want to add 30ma or so.
Any one have any ideas?
Thanks
Bookmarks