This simple 1-transistor audio preamplifier appeared in the June 1968 Radio Electronics magazine. The transistor is a general-purpose type of the time. The gain is 14 dB.
This circuit is from a 1980 publication. In it we have a half-wave power control in which the SCR...
We found this circuit in the 1994 Linear Applications Handbook from National Semiconductor. The...
This sound intensity meter was found in a 90s Elektor. The circuit uses an integrated device from...