1. Home
  2. Hobby Electronics Basics
  3. 4017 without a CLK signal

4017 without a CLK signal

Bit of a dumb question...

I have this 4017 decade counter chip that I want to use, but instead of hooking up a clock signal (like from a 555 timer IC) to the CLK pin, I want to be able to control the 4017 using a push switch. At the moment, I have the switch hooked up to +Vcc with a 100K pull-down resistor connected to GND. So when the switch is not activated, it receives a low input, and when the switch is being pushed, it receives a high input.

But every time I press the button, the 4017 is not changing its output smoothly.... it's skipping and changing at various speeds as I press and release the switch. What am I doing wrong? Tried changing value of the resistor but no joy.

Thank you

Reply to
bigtom28
Loading thread data ...

the switch will need de-bouncing - google this.

Reply to
feebo

try this

formatting link

Reply to
feebo

Ohhhh. I didnt think of that. No wonder. I'll look into it.

Thanks for that

TS.

Reply to
bigtom28

Hi, Tom. The easiest non-technical way to do this is to rely on the fact that a CMOS input is essentially infinite input impedance (it doesn't draw any current at all), but has about 10pF of capacitance to GND. You can hope this capacitance will hold the logic state while you use a single pole, double throw pushbutton (with normally-ON and normally-OFF contacts) like this (view in fixed font or M$ Notepad):

| | VCC | + | | | | | '---o | __--o-->To CMOS Input | .---o | | | | | === | GND | (created by AACircuit v1.28.6 beta 04/19/05

formatting link

For CMOS (and only CMOS) inputs, this might be enough to debounce your switch signal, as long as the switch is snap-action, close to the clock pin, and there aren't any external sources of noise like relay contacts or inductive loads.

Again, this *might* work. If not, you can use the advice of some of the other posts.

Good luck Chris

Reply to
Chris

put a capacitor from input to common. something like a .1

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
Reply to
Jamie

Thanks, but I'm pretty sure I tried that one already =)

Reply to
Jason S

want

receives

input.

Hello Jason, try this:-

+V o | +---+---+ | | +V |o | o || --- 0.047 | |o --- +---+----+ | | | 4017 | | | | | +---+---+--------|CLK | | | | +-+ | | | | +---+----+ | |220K | | | --- +-+ GND | --- GND

... Donkey

Reply to
Donkey D...

No actually, I lied. Its working. I used a 100K & 0.1uF greencap in parallel tied to Ground from Input, with switch hooked up +Vcc, seems to be working ok. BTW, Jason is my mate. Im Tom. Im just using his account. lol

** Problem solved**

Thanks.

Reply to
Jason S

Thanks Donkey, but the problem seems to be solved now. BTW, Jason is my mate. Im Tom. Im just using his account. lol

** Problem solved **
Reply to
bigtom28

No worries Tom. Glad you sorted it out. ... Donkey

Reply to
Donkey D...

Below I used a capacitor in parallel with the resistor to smooth out the button pushes.

formatting link

Reply to
Si Ballenger

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.