This circuit is from an English documentation from 1969. The circuit can be designed based on modern equivalent transistors. Diodes are general purpose types.
When the supply is established, the load only receives the supply some seconds later, a time that...
With S1 closed, when dark, the triac will supply the load with the power set in R4. The LDR is...
This interesting amplifier for frame antenna for the medium wave range was found in a Popular...