Introduction: Run a 4017 Decade Counter for One Cycle Then Stop

When making any electronic projects, have you wanted a sequence of events to transpire once and then wait for a trigger input? In my case I'm making a heart rate monitor with a funky visual display.

Well here's a handy way that uses the 4017 decade counter chip.

I used a 555 timer chip to regulate the timing of the sequence.
This instructable assumes you know how to use a breadboard and set up a 555 chip in astable mode.

The circuit starts when you push a button or give it a digital input to. It is active low, meaning the digital input must be a pulse to Minus or a brief connection to GROUND.

I've explained how to in the video in the next step.

Step 1: Connect Pin 15,13 and 3 Together




After setting up your 4017 chip with a timer such as a 555, let's set it up to run as a monostable device. IE. something that does something once and then waits for further input.

So take two scraps of jumper wire or whatever you usually use to do make such connections and connect pins 15, 13 and 3 together.

Step 2: The GO Button

Connect a button from pin 15, 13, or 3 to ground. When the circuit is waiting, this will kickstart it again by overwhelming the positive voltage from pin 3 and connecting pins 15 and 13 to ground.

Handily the button needs no debounce system because this circuit functions as a debouncer.

And of course you could trigger the circuit using something other than a push button. But I'll leave that up to y'all.

That's it. Pretty simple but handy for any one-time sequences you want to run.

Have fun kids.

Please leave me a comment if this was useful to you :)

Comments

author
mtcountrygirl made it! (author)2013-08-15

Great post! Thank you. I'm not very knowledgeable about circuits and your example is close to what I need. Instead of running an entire cycle I want it to increment each time the button is pressed and then stop. So 'press, initiate 1, pause, press, initiate 2, pause,' etc. Could you explain how to do that?

author
snotty made it! (author)snotty2013-08-15

Yeah for sure. Here's probably what you need to do: put a button on the clock input.

I think the clock input is "active high, edge triggered". What this means though is that when the clock input pin receives a change in voltage such as going from ground to 5v, the 4017 jumps forward one notch.

To set this up let's assume you're running a 5v system and let's assume that the clock pin is indeed active high. What you'd do is connect the input through a 100k ohm resistor to minus and then hook up a normally open button to +5v and the other side of the button to the input pin. This way the clock pin is not left floating (sometimes unconnected pins behave erratically) When you do nothing the clock pin has a bit of electricity flowing OUT of it (imagine the minus wire is like a vacuum cleaner sucking up electricity and the resistor is a big fluffy sock jammed in the vacuum cleaner hose. It still sucks but not super hard). Now when you push the button lots of electricity comes dumping out of the +5v side and into the clock pin (imagine the +5v wire is like a leaf blower farting out electricity). The flow of electricity reverses direction in the clock pin since most of the juice from the +5v side is going into the clock pin and only a little is getting sucked down through the resistor into minus. This change in direction registers as a clock pulse for the 4017.

Hmm let's see if I can do an ASCII schematic...

Plus+
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Button (disconnected until pushed) Pushing this overwhelms the "minus" input
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4017 pin 14 clock input (gets a weak 'minus' input until you slam down the button)
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Resistor (big number, low wattage is fine)
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Minus-


Confused yet?

author
innowation made it! (author)2013-04-21

Thanks was very useful to me,hope it works also for me. I already want to use
a Flip flop

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