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 purpose of this circuit is to sense the water level in the windshield wiper reservoir. The circuit...
The circuit illustrated in Figure allows external loads (8) to be driven from parallel port...
This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit...