This circuit also appears elsewhere on this site, obtained from other sources. This is an 80's American schematic book. Instead the lamp can be used white high-brightness LEDs.
The FET of this circuit of a 1971 publication may be the BF245. The circuit serves as a voltage...
July 2017 - Texas Instruments' new bidirectional current controllers LM5170-Q1 for power...
When a small air current reaches the piezoelectric sensor, a small audio signal is generated and...