This interesting 1924 triode tube receiver was found in a documentation by Gernsback. Observe supply voltages. Coils are for tuned wavebands.
In the figure we have a negative power circuit for SCR and unijunction transistor suggested by...
We found this oscillator in a documentation for radio amateurs from the 1970s. The circuit can use...
This 5 V power supply for TTL, Shields and microcontrollers is old, and the components can be...