3-tube receiver 2 (T1603E)

Using known tubes, this receiver was found in a Radio Electronics from 1949. The circuit does not include the power supply.

Power Control (Dimmer) (CB435E)
In the original circuit a 40431 quadrac is used, but this is not a common component today....
Limit Comparator (CB5084E)
This circuit, which appears in this section elsewhere, is from an American 1980s documentation....
555 Biofeedback Monitor (CB24775E)
This simple 555 biofeedback circuit was found in the December 1983 issue of Radio Electronics...