This rectangular signal generator was found in an Electronics World of 1966. The transistors are from that time and modern equivalents can be tested.
This interesting circuit was found in a French publication from the 1980s. The circuit indicates when a...
This circuit indicates when a 28 V lamp burns, lighting a neon lamp with higher voltage. The...
The noise comes from the PN junction of a common silicon diode. Since no gain is given by the...