This simple circuit has good gain and can be implemented with any general-purpose transistor. The circuit is from Electronics Now, June 1997. The coil determines the frequency range.
Lamps in the range between 20 and 50 mA can be used. Voltage supply is according the lamp and...
The purpose of this circuit found in an old documentation from the 90's is to switch on low...
This configuration, which appears elsewhere on this site, was found in documentation from the...