Double button microphone preamp (T352E)

This circuit was obtained in the 1937 RCA tube manual. Tubes are well known types that can even be obtained today. The power source is not given.

Electronic Dice with the 4018 (CB4630E)
A recreational application of the 4018 is shown in the figure in which we have electronic dice....
KMR 6 Keys Tactile SMT (COM035E)
It can be obtained from Mouser Electronics new tactile keys subminiature SMT KMR 6 Series C & K....
Preamplifier Using JFET (MSB012E)
This circuit is indicated to operation with piezoeletric transdicers or other with high impedance...