1-valve reflex receiver (T1557E)

Found in a 1924 book by Gernsback where we only have reflex receivers, this circuit uses high impedance headphones and battery power.

300 mW output stage (CB4280E)
This 80's circuit uses a germanium transistor like the AC121. The circuit has an output...
Simple 9V Power Supply (CB4367E)
This circuit was obtained from an English magazine from 1977. The magazine no longer exists, but...
Programmable Regulator TL431 (CB4640E)
The TL431 integrated circuit consists of a programmable shunt regulator with an internal...