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.
This circuit produces a signal at a frequency of 455 kHz, based on a ceramic resonator CSA455E, by...
This is the traditional configuration of the 7806 as a 12 to 6 V automotive voltage reducer. The...
This instrumentation amplifier with differential inputs was found in documentation from the 90s....