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Blinking LED

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By: kurt

Make an LED blink with this simple circuit. By using a 555 timer in astable mode, a square wave is generated. This square wave is output to the LED to turn it on and off. The LED blinks about 3 times per second with the values given in the schematic. The blinking rate can be varied by changing the resistors R1, R2, and the capacitor C1.

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Bill of Materials

Qty Part # Description Schematic ID Source
1 41bd4938af68bc803f33ddd1f8dda4d6902f60f1 NE555N IC, TIMER IC1 Source
1 A9d8f3614bcec6d0341317ce35862a70d692a376 ECA1EHG101 CAPACITOR, 100UF, 25V C1 Source
1 A0ff3ab201a9c105cb1f0720fa3859f44c920eba BS6I SNAPS 9V 6" LEADS I-STYLE 9V_BATTERY_CONNECTOR Source
1 Dffd8453bea3aff79b960b8a5cecb5a7b3ec1f0c CF14JT1K00 1/4w 1K ohms 5% Carbon Film Resistors R1 Source
1 A7c88c699ae93df915e3fce25b261df5db07b5f1 CF14JT2K00 RES 2K OHM 1/4W 5% CARBON FILM R2 Source
1 F3de1730e1c5c8a8cf1c375eace429ecf63eb1e4 CF14JT470R RES 470 OHM 1/4W 5% CARBON FILM R3 Source
1 45030f5359ca883029e7ac046bdca8276d1557d3 WP7113LID 5MM LOW CURRENT RED LED, LAMP THOLE, BULK LED1 Source
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1. Insert 555 timer

Put the 555 timer IC in the middle of the board at the top. Make sure that the notch/dimple is at the top of the chip when you put it in the breadboard.

P5153500 P5153502

2. Add wires

Place jumper wires as shown. The left rail will be used for ground, and the right rail will be +5V. Next, we will insert the 100uF capacitor.


3. Insert capacitor

Step 2: Insert the 100uF capacitor as shown. The positive lead should connect to the orange and purple wires on the right. The negative lead is marked by the white stripe going up the side of the case. It connects to the orange wire in the bottom left.


4. Insert LED

Insert the LED. The longer lead is the positive lead. It will be connected to the 470 ohm resistor in the next step. The negative lead connects to pin 3 of the 555 timer.


5. Insert 680 ohm resistor

Insert the 680 ohm resistor as shown. It connects the positive lead of the resistor to the white and green wires. This resistor limits the current that flows through the LED since LEDs act like short circuits when they are forward biased.


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13 - fixed a typo
12 -
11 -
10 - changed LED part
9 - added project image description.
8 - changed 9V connector part added file descriptions
7 -
6 -
5 -
4 - updated parts so they have images now.
3 - added parts
2 - deleted missing step image. added parts. updated schematic.
1 -
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