Instructables

An easy to make, cheap and simple LED-blinky circuit with CMOS 74C14

Sometimes you need simply some blinky LEDs, for chrismas decoration, blinky artworks or just to have fun with blink blink blink. I'll show you how to make a cheap and simple circuit with up to 6 blinking LEDs.

Note: This is my first instuctable and i'm not a native english speaker - so please excuse my mistakes.


 
Remove these adsRemove these ads by Signing Up

Step 1: Parts you need

Picture of Parts you need
So you need some cheap electronic parts, here we go:

- 1 CMOS 74C14 - its a small and really cheap microchip, we use it to create oscillators to make our  LEDs blink
-  some jumper wires
- a breadboard to stick the parts on it
- a 9V block battery with batteryclip
for further experiments a potentiometer around up to 1 M

for every LED-Circuit (you can add up to 6 to one chip) we need
- an LED ;-)
- a capacitor (around 4,7 µF, you may vary the value to get different blink frequencies)
- a resistor 100k-200k
- a resistor to limit the led current, around 1-3k

Step 2: Okay lets stick it together

lets go to our first blinky cirtcuit. Place the CMOS Chip in the middle of the breadboard as shown on the image.

Connect pin 7 of the chip with the ground (-) and pin 14 with the VCC (+)-bus on the breadboard.

Now connect the capacitor to pin 1 and the ground (attent to the direction, there is a minus printed on the Cap - that lead goes to the ground). Place a 100k-200k resistor between pin 1 and 2 of the chip. Then you need to add the series resistor (1-3k) between pin 2 and the LED. Attent to the right direction of the LED. The shorter leg goes to the ground.

I hope you may see it on the image.

If youre done, connect the batty to the plus and minus bus of the breadboard and your first LED should start blinking. :-)

Thats fun! Lets go forward, add more LEDs...

mathews4 years ago
Good little circuit. If you wanted to expand it, you could replace the LED with a transistor, and use that to source a few more LEDs (which could be placed in amongst other sets of LEDs operating at different frequencies).

You could also replace the resistor between pins 1 and 2,  with a pair of resistor and diodes in series. You can use this to adjust the mark/space ratio of the oscillation.

          R1      Diode
   |---===----|<|----|
--|                          |-----
   |---===----|<|----|
          R2      Diode

Combining these two will allow you to make a more random twinkling pattern for xmas lights.
Lapin14 years ago
Neat little circuit. Your link to Drawdio! does not explain the theory so well.
I personally prefer Fairchild application note: www.fairchildsemi.com/an/AN/AN-118.pdf.
Thanks for writing.

mischka (author)  Lapin14 years ago
Thanks for the link. There's a video of that japanese fountain that describes it very handy and simple. But your link of course provides more information.
lucas_m4 years ago
Great project; I've been looking for something like this for some time now... I just have one question: Can you replace the CMOS chip used with a TTL version of the 7414?
mischka (author)  lucas_m4 years ago
I think it would be possible with any CMOS Hex Schmitt Trigger Inverter chip. If you have one just try it out ;-), think you cant destroy something.
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!