The circuit shown indicates voltages from 10 to 14 V used to monitor automotive voltage. One or two LEDs light up depending on the voltage.
This article is old, from 1994. But, for those who have an old PC and want to use a joystick from...
The passage of an object in front of the LDR, producing a shadow or even turning off the ambient...
The transistor used in this circuit is uncommon today. AC124 or equivalent such as AC188K and...