Bench thermometer (CB20501E)

With an ultra-low consumption, this circuit can be powered by solar cells. The circuit is from a 1991 documentation.

DAC with the 7490 (CB13558E)
This simple 4-bit digital-to-analog converter was found in a 1974 publication. The transistors can be the...
Theremin CMOS (CB10231E)
I found this circuit in an American magazine Hands On Electronics from September 1987. The...
Micro High Voltage Generator (CB25720E)
Of course, the current is extremely small, but a voltage of 300 V can be obtained from 9 V of a...