This is the Fade LED. It is a small circuit that fades on and off when you open or close the circuit. It runs on a 555timer and a 2n222 transistor. It is a small and easy circuit.
Step 1: Components
In this circuit you will be needing:
1x 9v battery
1x 9v battery connector
6x jumper wires
1x 220uf(or more) capacitor
1x 2n222 transistor
1x 555timer chip
2x 10k resistor
1x 2.2k resistor (depends on how much current your LED wants)
Step 2: Components Footprint
If you are not yet familiar with the components footprint, then it may be a good idea to know them.
In the image above, it will show you the component footprint(symbol) along with what component it is.
Step 3: Build It!
Now you are prepared to start construction!
One image above shows you each specific components value, while the other shows the overall breadboard.
Remember the way the way the way the 555 timer and transistor faces. Note: ignore the '555' written on the chip, follow the numbers on it.
Step 4: Test & Finish
Now that you are finished, you can test you circuit to see if it functions.
Yes: If it works then this would happen: When circuit is on, LED will take a few seconds before it lights up. Once it lights up, it should stay lit. When you turn off the circuit, then LED should slowly fade off.
No: If the LED does not fade, you have either linked the capacitor the wrong way or the chip the wrong way. If the LED simply does not light, then you have a wiring error, so you should check again.
Step 5: Tricks
Now you have a working circuit, you can try modifying it.
To change then fade amount, you just change the capacitor. The more capacitance there is, the longer the fading lasts and vice versa