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.
The cut-off frequency of the filter shown in the figure can be adjusted to values between...
This circuit was found in a Popular Electronics from the 90s. The components used are all common...
This circuit uses a dual floodgate MOSFET not very easy to obtain today. Its handling is very...