4017 IC PB Advancement

[danuke]

Hi,
I'm looking at trying to make a circuit that will light LED's in sequence using a 4017 (have several on hand). The only thing is that instead of using a pulsed clock from an IC such as a 555 timer, I would like to use a pushbutton. Is there an easy way to accomplish this? All help is appreciated.

Thanks...
Joe

 

[chemelec]

Hi,
I'm looking at trying to make a circuit that will light LED's in sequence using a 4017 (have several on hand). The only thing is that instead of using a pulsed clock from an IC such as a 555 timer, I would like to use a pushbutton. Is there an easy way to accomplish this? All help is appreciated.

Thanks...
Joe

A Pushbutton to ground, from a 100K Resistor to the Supply voltage.
The output is between the Switch and the Resistor.
Everytime you push the button, the Signal goes low.

 

[philba]

I think you want each press of the button to advance the LED sequence by 1. right?

A push button as described above will work but will very likely have the problem of bounce. Any mechanical switch will bounce several times before settling. This will be interepretted as multiple button pushes. You will probably want to build a debouncer. There are a lot of ways to do this. Look here for probably the best treatment of debouncing by Jack Gansle - http://www.ganssle.com/debouncing.pdf He gives lots of hardware debounce circuits. It is a must-read if you are using switches for anything other than power.

 

[danuke]

I'm having trouble with a 4017 IC. I have it wired up as follows:

Relay to debouncer (https://www.elexp.com/t_bounc.htm - Figure 2)
-R = 1M ohm
-C = 0.1 uF
-Relay completing the circuit to ground for the switch
-Using a 4011 IC with inputs tied together to make a NOR gate
-I calculated this to give a 0.1 second debounce time
NOR gate to Clock on 4017
Output to LED's having common cathode (vertical stripe on breadboard)
common cathode strip to resistor (470 ohm)
470 ohm Resistor to ground
Everything is powered from a single 12V 5AH Lead Acid battery

The issue I'm having is that it transitions as 2 pulses when i trigger the relay. If I trigger the relay within a very short time frame after it is released it will pulse as 1 cycle, advancing by 1 led. If I wait more than roughly 1-2 seconds it will advance by 2. Any ideas on the issue?

Thanks,
danuke