Found in documentation from the 1980s, this circuit can have several adaptations to use modern transistors and LEDs instead of the lamp. The power supply voltage can also be changed.
This circuit was found in an old American magazine for radio amateurs. The circuit is based on a...
The LDO series (Low Dropout) TPS80 from Texas Instruments (www.ti.com) can provide output voltages...
This circuit is from Motorola's 1990 Linear Databook. We can implement it with other operational...