Found in a 90’s American documentation, this circuit indicates the frequency of input pulses up to 1 kHz. The circuit has a very explored configuration on this site.
This astable multivibrator using two transistor controls two small 50 mA lamps. The lamps can be...
This circuit uses an SCR as an active component, working only at short distances. The circuit was...
This circuit, shown in the figure, consists of a variable gain amplifier with differential input...