This interesting 1924 triode tube receiver was found in a documentation by Gernsback. Observe supply voltages. Coils are for tuned wavebands.
This circuit was obtained in a Popular Electronics of 1991. The magazine no longer exists, but the...
With this voltage regulator we can have currents up to 4 A at a 5 V output for TTL circuit power. The...
This circuit was found in February 1976, Radio Electronics magazine. The circuit is quite...