This circuit was found in a 90s American publication. The same configuration appears in several places on this site, obtained from different sources. The lamps can be replaced by LEDs.
Circuits similar to this appear elsewhere in this section. The transistors can be BC549 (low...
This circuit was found in old documentation, however the components used are common today. The...
This circuit, which can also be adapted to function as a microcontroller shield, is from 2003...