We found this circuit in a Hands-On Electronics from the 90s. The circuit must be connected to an external amplifier. Frequency control is capacitive, using an antenna for this purpose
This circuit detects traffic problems on a miniature railway by triggering an alarm. The circuit was...
When establishing the voltage at the input of this regulator, the output voltage rises smoothly until...
This circuit was found in a Motorola documentation from 1975. Modern equivalent transistors such...