This simple circuit for a common 110 V power grid was found in a 1980s American documentation. The circuit uses neon lamps as indicators.
This circuit is from September 1984 Radio Electronics. The frequency can be changed by changing C1 and...
This optical coupler for short distances is powered by 12 V which is the voltage of the lamp and...
This circuit was found in a 1980s Intersil documentation. The integrated circuit used is not...