We found this circuit in the August 1994 issue of Electronics Now magazine. The circuit is based on the now uncommon CMOS 4046. The frequency range is given by C1.
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...
Using only one general purpose transistor this circuit is powered by batteries. The lamp of the...
Can be used as a shield, this old American documentation circuit offers digitally selected...