Published by Philips in 1965 documentation, the sensor for this circuit is a common LDR. The transistors are general-purpose types from the time, only TR3 is a power type according to the load.
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...
This timer activates a relay after a time interval of up to 15 minutes has elapsed, starting from...
This circuit was used to regulate the speed of small DC motors of cassette recorders. However, if the...