This circuit provides a reference voltage of 2.5 V adjusted in the trimpot. The transistor can be the BC558 (in the drawing it came out as NPN). The control is done by a rectangular input signal.
This old amplifying stage was found in radios and small amplifiers of the time. The circuit is...
This crystal-controlled oscillator can generate signals as high as 200 MHz. The L1 coil is made up...
The circuit shown in the figure is triggered by an input voltage determined by the setting of P1....