This low frequency oscillator circuit was found in an Electronic Design from the 90s. The transistors are common types, and the frequency is given by the crystal.
This solid-state relay (SSR) or shield was found in a 1995 Electronics Now. The transistor can be...
The components used in this National Semiconductor circuit are not common today, but the...
The circuit presented in the figure is an amplifier for stereo sources with the Maxim MAX9723...