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4017 without a CLK signal

B

bigtom28

Jan 1, 1970
0
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
 
F

feebo

Jan 1, 1970
0
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

the switch will need de-bouncing - google this.
 
F

feebo

Jan 1, 1970
0
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

try this

http://www.ece.utep.edu/courses/web3376/concepts/debounce.html
 
B

bigtom28

Jan 1, 1970
0
the switch will need de-bouncing - google this.


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

Thanks for that

TS.
 
C

Chris

Jan 1, 1970
0
bigtom28 said:
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

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 www.tech-chat.de)

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
 
J

Jason S

Jan 1, 1970
0
Jamie said:
put a capacitor from input to common. something like a .1

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

Donkey D...

Jan 1, 1970
0
bigtom28 said:
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

Hello Jason, try this:-

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

Jason S

Jan 1, 1970
0
Jason S said:
Thanks, but I'm pretty sure I tried that one already =)

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.
 
B

bigtom28

Jan 1, 1970
0
Donkey D... said:
Hello Jason, try this:-

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

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 **
 
D

Donkey D...

Jan 1, 1970
0
bigtom28 said:
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 **

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

Si Ballenger

Jan 1, 1970
0
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

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

http://www.geocities.com/zoomkat/RSswitcher.htm
 
J

jasen

Jan 1, 1970
0
Bit of a dumb question...

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.
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?

you're not accounting for "contact bounce".

A 0.1uF capacitor across the resistor may be enough to fix it.


Bye.
Jasen
 
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