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LED Circuit mind of its own

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kenwalus

New Member
I have built a LED circuit that cycles 4 led’s with the push of a button. I am using a CD4017 and triggering it with a LM555. When I trigger the LM555 (pin 2) with a pushbutton the output is sent to the CLK of the CD4017. This causes it to advance one light. I have built 24 of these and they are located throughout the shop. This works fairly well so I took it a step further. I made a Master box that sits in the office. It has 24 sets of 4 LED’s that represent what is displayed on the small boxes. From each small box I send the same signal that I use to trigger the first CD4017 and have it trigger a duplicate CD4017 circuit. The lights will change at the same time . The problem that I am having is that the master box LED’s will change sometimes by themselves. I must be getting a stray signal from somewhere. Can I put a filter in the circuit? Any suggestions?
 

Boncuk

New Member
Hi,

that kind of behaviour might have many reasons, such as stray AC causing a timer circuit to be triggered or a false count pulse with the same effect.

It would be helpful if you post an entire schematic diagram of the master and remote panels.

Also distance between boxes and the kind of cable used has influence on the proper function of the circuit.

Boncuk
 

kenwalus

New Member
I will try to upload a schematic GIF format.
The boxes are connected with CAT 5 cable to the main Junction Box. The furthest box is @100 ft away

LED Schematic box.GIF
 

pcbheaven.com

New Member
If you use only the CMOS and the 555 you mentioned, it would be good to have more than 5v supply, 9 or 12 would be better for the I2R loses. Also, a question. Have you add a pull up resistor?
 

sheldonstv

New Member
post a schematic so that we can see what you have built...we wont b scared of it!!!...also are u edge triggering yr 555?if u have a pushbutton connected so you ground pin 2 -as u release yr pushbutton u will have switch bounce which will cause unpredictable results regarding triggering and how long are the leads that connect the trigger signals to each 555?too long a lead length if its picking up electrical noise will also cause false triggering.... ive uploaded a switch debounce circuit for edge triggering yr 555 ........
 

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sheldonstv

New Member
2 things with yr circuit-there is no power on reset....and the 555 needs to be edge triggered as my previous schematic shows with switch debounce......heres a revised 4017 schematic...also make sure there is adequate decoupling across supply lines and on the 555 timer add a 0.1mf from pin 5 to pin 1..........
 

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k7elp60

Active Member
2 things with yr circuit-there is no power on reset....and the 555 needs to be edge triggered as my previous schematic shows with switch debounce......heres a revised 4017 schematic...also make sure there is adequate decoupling across supply lines and on the 555 timer add a 0.1mf from pin 5 to pin 1..........
The 555 doesn't need debouncing to trigger with a switch has shown.
 

k7elp60

Active Member
I will try to upload a schematic GIF format.
The boxes are connected with CAT 5 cable to the main Junction Box. The furthest box is @100 ft away

View attachment 30960
I see three problems with your posted circuit.
1. Pin 4 of the 555 needs to be connected to pin 8
2. You need on resistor about 680Ω between the common LED line and ground.
3. You need a decoupling capacitor between +9V and ground, preferably close to the 555.
 
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kenwalus

New Member
Thank you

Thank you everyone for your replies and suggestions
I will try next week and see how everything works out
I willpost a final schematic when I finish

Ken
 

sheldonstv

New Member
regarding switch debounce-if the timed period is quite short the switch bounce will cause the 555 to retrigger and the 4017 will recieve more than the 1 desired clock pulse....switch bounce doesnt need to be a problem and there isnt much xtra circuitry to prevent it...also if he has long leads from his console to each circuit,a good clean switching signal is needed i have used 555s for quite a lot of things and switch bounce can cause strange things to happen with a 555.....
 

kenwalus

New Member
LED mind of it's own update

Well I have added a few ideas that I obtained from everyone and I think I have a Frankenstin. I have added the debounce circuit and it toggles fine. When I connect the Circuit with the 555 and the 4017 to the second 4017 circuit, I try to go to Prekit (which is the reset) the led will not come on. If I hit the switch again the prekit LED will come on but then change to Setup.
Schmetic attached. Any Ideas?
 

sheldonstv

New Member
no schematic????
 

audioguru

Well-Known Member
Most Helpful Member
The ordinary 555 causes a 400mA supply current spike when its output changes state. Then the CD4017 counters get all confused when their supply voltage suddenly drops when they are clocked.
Use a Cmos 555 (LMC555, TLC555 or ICM7555) which does not have such a high current spike.
 
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