This circuit is from an 80's publication. It makes use of small 6 V x 50 mA incandescent lamps. The diodes can be general purpose or even 1N4002. The transformer is 6.3 V with 100 mA or more current.
This is a configuration much explored by assemblers, being found on this site in dozens of similar...
September 2016 – At Mouser Electronics is available audio drivers for the purpose of suitable...
This circuit has a thermal chamber that acts as a stabilizer, compensating for the ambient...