This audible continuity test was obtained in a book from the 90's describing simple projects. The feeding is done with a single battery.
We present a DC-DC converter circuit that can operate with input voltages from 2.4 V to 14 V and...
We found this circuit in a Texas Instruments documentation from the 80s. The circuit uses simple...
This circuit was obtained in a 1965 American magazine translation. The coil is formed by 40 + 40...