Solar flashlight (CB20488E)

This circuit charges a battery to power a flashlight at night. The circuit is from an English publication from 1991.

110 to 220V Voltage Elevator (CB4575E)
This circuit is from 1995 documentation. The power depends on the transformer, which in this case...
Flip Flop Debouncer (CB4813E)
EDN magazine in a 90's issue published this TTL technology debouncer flip flop circuit, in this...
Current Amplifier (CB6136E)
This circuit was found in a British documentation from 1969. It can be implemented with modern...