Using a Decade Counter to Make LEDs Flash

[Andrea De Napoli] created a LED display consisting of a half-dozen LEDs connected to the inverted signals of a CD4017 decade counter, giving the effect that a dark LED is running back and forth. The CD4017 works by activating 10 outputs, one at a time, as controlled by a clock signal sent to pin 14.

The first and last LEDs are lit by outputs 0 and 5 with the help of a PNP transistor and a 12K resistor. The middle four LEDs are switched by two outputs each and go dark when one of them goes high. [Andrea] really delves into the CD4017 and he shares a lot of detail in the project page.

Hackaday publishes a lot of posts about obscure ICs: Project 54/74 aims to create a database of die images of 5400 and 7400 series ICs. In a remix of a classic, the Baby 10 uses a 4017 to make a music sequencer.

20 thoughts on “Using a Decade Counter to Make LEDs Flash

  1. There was a time when the first electronics everyone did (not talking primary school hook up light bulb to batteries) was with a 4017 and a 555.

    Googling to find the history of the 4017 I see it’s now in the GCSE curriculum.

    Shame they spent all that money on the microbit and not teaching.

      1. I’m wrestling with this –academic, I think–‘argument’.

        Is the implication, “Expensive teachers don’t teach but the inexpensive Microbit does”?, or “Expensive teachers teach, but the inexpensive Microbit does it so much better”?. or…what, precisely?
        How, exactly, does the inexpensive Microbit, even with the aid of those obscenely expensive teachers teach electronic design which does not require a microprocessor? How does the Inexpensive Microbit teach that a microprocessor solution might not be the best solution?. How does…

        Common sense and critical thinking are, unfortunately, uncommon.

  2. I remember making something like that in about 1981.
    74C4514 for the 4->16 decoder,
    4 bit up/down counter. I don’t quite remember, perhaps a 74C193?
    Quad nand, perhaps a 4093, for the RS FF to control the up/down count direction and make the clock.

    I had multiple LEDs per ‘4515 output, arranged in a circle to give the appearance of two pairs of lit LEDs chasing around the circle in opposite directions simultaneously.

    1. On second thoughts the up/down counter might have been a CD4029 or MC14516, which have separate clock and U/D inputs. The ‘193 has an up-clock and a down-clock input which makes it harder to use in that application.

  3. Good work, Andrea. You’re proof that true electronics design is still alive.(“Oh yeah, I can do that with a Raspberry Pi and a CPLD; a little bit of code–you can do anything with code–…”)

    Keep up the gread work. We’re all looking to see much more good stuff from you.

  4. I remember using a few dozen decade counters each of their outputs attached to darlington drivers and diodes to drive a couple of infrared leds. The darlingtons switched by shift registers. Clocked at just the right frequency it could chuck out any tv control command, of loading all the timing and most of the processing.

    1. A rats nest, long dismantled, I used to talk to it via a parallel port from a batch file, chucking out commands, heath robinson style. Variables, echo to file, pipe to debug. Even going as far as reading the input pins back to variables again. Slow messy but if it works it’s not stupid. It made a great vcr record timer.

  5. HaD says: “Hackaday publishes a lot of posts about obscure ICs…”

    Come on HaD. The venerable CD4017 is FAR from “obscure”…

    A 30 second search of DigiKey for the 4017 part comes up with tens of thousands available for immediate ship in lots of versions and packages. At first-glance even the old-standby PDIP 16-pin CD4017BE is qty. 4,808 ready to ship immediately in qty.-1 at $0.52 each!

    So yeah – HaD says “Hackaday publishes a lot of posts about obscure ICs”.

    OK – But THIS particular post is NOT about an “Obscure IC” at all!

    Have Fun Everyone, David

  6. Coming up this week on Hackaday:
    – 555 blinking LED
    – 4017 LED chaser with 555 clock
    – 4017 (with 555 clock) “electronic dice”
    – Multivibrator alternating LEDs with two transistors, two LEDs and two capacitors

  7. Glad to see having fun with discreet logic chips is still a pastime. Doing this sort of thing helps build a fundamental understanding of electronics for advanced projects(CPLD’s and FPGA’s). Even to this day with embedded processors I still find a use for basic gates in design. So I keep a supply of AND, OR, NAND, NOR, XOR and Inverters on hand. I particularly like the single gate surface mount packages.

  8. The CD4017 is a standard part in my stock parts bins. It’s just such a useful part! I’ve honestly used the 4017 even more than I’ve used 555 timers! I most frequently use them in nixie tube clocks. Who needs a stinkin’ micro when you have a clean time pulse and a series of counter dividers! :D

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