This circuit by Ferranti, in a 1967 publication, is intended for reading perforated tapes. The circuit uses transistors from the era that can be replaced by modern equivalents.
The integrated circuit in this application for 6 V motors is not common today. The circuit is from...
When this circuit picks up a louder sound it produces a pulse that briefly charges the 10 uF...
The circuit is from the Linear applications Handbook of the National Semiconductor of 1994. The...