This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The triac is according to the controlled load. The sensor is a common LDR.
This circuit was found in a QST from the 1990s. The circuit expands the scale of a 10V instrument to...
This 8 ohm output amplifier was found in a 1968 Motorola publication. The circuit uses transistors...
This general-purpose preamp configuration was found in the 1960 Mullard transistor reference...