We need the following components:
one LTR-4206E phototransistor
one lithium CR2032 battery (3 V)
2N3904 transistor
1K resistor
Photos of these components:
Progress:
First, take a Transistor and a resistor and solder them as shown in the figure:
Next, we solder a phototransistor to this structure:
Next we will attach Light-emitting diode :
And then the power source:
And now let's see what we got:
This light will turn on when it gets dark