The circuit shown is from the 1977 GE semiconductor manual. More modern equivalent SCRs can be used. R1 must be wire type.
This old fashioned amplifier can source some watts to a low impedance loudspeaker. The circuit...
This circuit is from a 1975 amateur radio manual. The components can be approximated to the...
This circuit receives the local stations of medium waves listened to in a piezoelectric capsule or...