5-tube commercial radio (T1619E)

This commercial superheterodyne receiver was found in a 1949 Radio Electronics. The circuit uses battery.

Fixed Passage Sensor Alarm (CB18115E)
This 2003 circuit uses two types of sensors: by reed-switch and by infrared. If the magnetic...
RC Coupled One Transistor Stage (CB965E)
This one transistor stage for audio signals was found in an old publication of the year 1958. The...
LM324 High Gain Amplifier (CB25969E)
Using the four amplifiers of an LM324 this circuit was found in the June 1996 issue of Electronics Now...