This 6-transistor radio was sold in Japan in the 1960s. The super-heterodyne circuit for the OM band was powered by ordinary batteries.
This sonic, sound or vox switch uses common SCR and transistors can be BC548 or equivalent. The...
This circuit allows you to use a calculator as a timer by directly activating a sum key with...
This circuit is from the time when photos were revealed in darkrooms. We found it in a 1968...