This circuit was found in RCA documentation from the 1960s. The circuit uses components from that time and can measure speeds up to 10,000 rpm.
The circuit, shown in the figure, consists of an audio oscillator that generates signals between...
This circuit was found in a 1992 PE Hobbyst. The circuit detects the presence of spy...
This circuit produces low power flashes in a LED. Frequency is adjusted by P1 and depends also on...