This alarm is either activated or triggered after a certain amount of time, giving the owner time to exit or enter and disarm it. The circuit is from a Radio Electronics from April 1975.
Measuring capacitances and resistance this simple instrument was found in Radio Electronics...
The LM143 integrated circuit is a high voltage operational amplifier from National Semiconductor that is...
We found this circuit in the November 1985 issue of Radio Electronics magazine. It uses TTL...