Two-tube regenerative receiver (T1595E)

This circuit is from a Radio Electronics from 1949. The circuit is battery powered and has high impedance listening.

Transistor Push Pull Power Amplifier (CB20005E)
This circuit of a few watts of power shows a typical configuration from the 70s using driver and...
Gain Relay Excitation Circuit (741) (CB11882E)
Signals ranging from a few millivolts to a few volts can be used to excite a relay with this...
15 W Class D Stereo Audio Amplifier (CB12952E)
The circuits shown in figure 2 are suggested by Texas Instruments (www.ti.com) make use of the...