This resistance meter was found in an English documentation from 1989. The operational amplifier admits an equivalent and the transistor can be a BC558 or BC559.
27 MHz Transmitter (CB14008E) This circuit was found in a Japanese publication from the 1970s. The...
This circuit reproduces in a small loudspeaker the sound of the signal that modulates a...
The integrated circuit used in this multivibrator is no longer common today. With the components...