- Published in issue 7/1991 on page 55
Switch-off for battery supply
A frequent annoyance with battery-operated equipment is that just after you switch it on you notice that the battery is fIat. Quite probably, the last user (you?) has forgotten to switch it off. The circuit described here makes sure that this will never happen again. A touch on the button, S1, is sufficient to let the equipment work for a predetermined period only.