This vibrato circuit was found in Motorola's 1966 documentation. The circuit uses transistors of the time that can be replaced with current common types. Power is done with 3 9V batteries.
We found this shield circuit in the SGS Integrated Circuits Manual of 1982. The circuit is...
This circuit with transistors and a crystal microphone appeared in Radio Electronics magazine in...
This circuit amplifies the signals in the UHF band starting at 470 MHz, reaching just over 900...