We found this circuit in December 1986, Radio Electronics magazine. It uses 3 inverters and has the frequency determined by the crystal. The power supply is 5 V.
Texas Instruments' low power operational amplifiers OPAx196 can be found on Mouser Electronics....
This circuit operates with input voltages from 50 to 140 V providing an output of 12 V under...
This circuit mimics the sound of a siren when we turn the axis of the small DC motor. The...