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 simple circuit controls the brightness of an LED from LDRs, NTCs, PTCs or other resistive sensors....
We found this circuit in a 1990 documentation. It draws one out of 10 numbers and during the draw...
The circuit shown in figure 3 uses a programmable unijunction transistor (PUT) of the BRY39 type...