We found this circuit in a Philips documentation from 1965. The circuit uses a common LDR sensor and the transistors are general purpose types. TR2 can be a BD135.
The trip circuit for this alarm is given in CB16765E. The circuit uses common components and acts...
This circuit is from an old American publication from 1970, but it can be assembled with a BF494...
This circuit found in 1969 Popular Electronics is used to power a gas laser. The circuit produces...