We found this simple protection with zener diode in a 1967 Motorola documentation. The zener diode is 18 V, but the components can be changed for operation with other voltages.
This mechanical reverberator circuit for guitar was found in the February 1970 issue of Radio...
This circuit generates high pulses from a sinusoidal input, using SCRs for this purpose. The...
September 2016 - It can be purchased from Mouser Electronics the new ultraviolet high power LEDs...