Found in an American documentation from the 90s, this circuit uses small low voltage lamps (6 to 12 V0. The circuit can be adapted to use LED indicators.
This circuit is from a Japanese publication in 1967. The circuit uses a Geiger-Muller valve and...
Motorola's LM13600 integrated circuit is not very common today. The input voltage is 10 mV. We...
This circuit is from a 70s linear integrated manual. The integrated circuit used is uncommon today...