How to Make an Alternating LED Flasher




Introduction: How to Make an Alternating LED Flasher

Using the 4001 quad nor gate CMOS IC and a few other basic parts, build this simple alternating  LED  flasher.

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Step 1: Parts

-4001 quad nor gate
-2.2k resistor
-1meg resistor
-1k resistor
-10 uF capacitor
-100k pot
-Solid core wire
-2 LEDs

Step 2: Insert the IC and Jumpers

Insert the IC over a slot in the breadboard and make jumpers.  Connect pins 1 and 2, 5 and 6, and than 3 to 5. Pin 7 goes to ground.  Finally, pin 14 connects to 6 volts. 

Step 3: Components

That 10 uF cap connects to pin 4 (+) and an open row closest to the IC (-).  The 2.2k resistor connects to the same row of the negative on the capacitor.  Connect the 1meg resistor to that same row and that to pin 1.  Connect one of the LEDs anodes to pin 4 and the cathode to a free row.  Connect the other LEDs anode to pin 5, 3 or 6 and the cathode to the same row as the others.  Connect the 1k resistor to that same row and then to ground. 

Step 4: The Poteneometer

Solder wires onto the pot.  Connect one to pin 3, 5, or 6 and the other to the 2.2k resistor and test it out.  Use the pot to adjust the speed of the flash.

Step 5: Schematic

Step 6: Troubleshooting

If the circuit fails to work;

-Check if the IC is hot.  If so make sure its not inserted backwards or that the power connections are reversed
-Make sure the LEDs and the capacitor are not in backwards
-If it still fails to operate take apart the circuit ad build it again!

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    5 Discussions


    5 years ago on Introduction

    Where's the 3rd resistor... the 100k resistor that is in the diagram connected to 2.2k resistor? o_O


    8 years ago on Introduction

    Hi there whats the operating voltage for this circuit. The project just right for which i need it for. Looking forward to building this . thanx peeps


    9 years ago on Introduction

    i like this, but i need two things:
    1- could you post a video?
    2- what does the chip say on it?


    Reply 9 years ago on Introduction

    Glad you like it but no, I will not post a video, just look at the schematic, and the chip says: MC14001BCPJT985C.