This simple circuit makes use of neon lamps to indicate the voltage of a power grid. The lamps are common neon and the circuit indicates whether the voltage is 110 V or 220 V.
We found this configuration in a technical documentation from 1974. It can test both TTL logic...
The current can be kept constant in the load circuit using the integrated regulator LM350. The...
This circuit was found in an Elektor from the 90s. The integrated circuit is uncommon today. This...