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.
This SCR circuit activates a buzzer when triggered. The circuit is from a Popular Electronics from...
June 2016 - It can be purchased from Mouser Electronics the TAS5720x the evaluation module from...
This circuit was found in a National Semiconductor manual from the 1970s, appearing in articles and on...