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.
We found this circuit in a 1995 documentation. It is a two-channel preamplifier for supplying a...
In the figure we have the way to connect solar cells in series in order to increase their voltage. The...
This circuit is from the 1990 Motorola Data Databook. The circuit can be implemented with...