This 40-second delay switch was found in a 1965 Electronic Design. The unijunction transistor might be the 2N2646 and the SCR a sensitive modern equivalent.
This transformerless 16-ohm speaker circuit was found in a Radio Electronics from October 1963. The...
In the figure we have a solar power source for experiments with this type of energy. The cells must...
This circuit was found in a 1986 documentation and it may be difficult to obtain some of its...