Found in a 90s Popular Electronics, this transistorized circuit generates pulses from 2 Hz to 50 kHz in three selectable ranges. The circuit has both AC and DC outputs.
This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The...
This thermistor circuit was described in an article in Radio Electronics magazine from February 1963....
This is one of the possible configurations using the LM139, 239 or 339 voltage comparators. The...