Using the 555 and 7400 this circuit was found in the September 1977 Radio Electronics magazine. The power supply must be made with a voltage of 5 V.
The quiescent current of this alarm is in the order of microamps and the same is true for the...
This circuit is from a 2005 Linear Technology publication. It converts current into load sensing...
This circuit can operate in a 100 dB range with signals of up to 100 MHz frequencies. Similar...