This adjustable frequency circuit was found in December 1986, Radio Electronics magazine. The base frequency is given by C1 and the power supply must be 5 V.
We found this circuit in the magazine Eletcronics Now of July 1994. The power supply is according to...
This circuit uses the 7815 regulator to obtain a voltage for motor control num shield for PC. The...
This simple Philips circuit from the 1960s can use any general-purpose transistor. The signal is...