This circuit was found in a 90s European documentation. The circuit already includes a powerful amplification stage. The MOSFET can be of any type.
This experimental amplifier was found in the 1960 Mullard transistor reference manual. The...
This circuit from Motorola is from 1968, appearing elsewhere on this site. The transistors admit...
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...