Some trouble with IC 4017

Thread Starter

enesene

Joined Mar 3, 2020
17
Hi. I just want to prepare a led roulette circuit. I set it on some programs to make sure it works correct. But it doesn't work at all. What's wrong with it? Looks like it should work shouldn't it?

IMG-20200311-WA0009.jpg
 

dl324

Joined Mar 30, 2015
10,536
What is the circuit not doing correctly? Where is your ground connection?

EDIT: I see it now. You have the battery backwards.
 

ElectricSpidey

Joined Dec 2, 2017
1,070
Mr. Guru, you do know that's a sim...right?

In an actual circuit I wouldn't recommend using a single resistor to limit the LEDs, with open collector outputs...ok...but not with CMOS outputs.

In a proper roulette circuit the 555 runs in astable mode and the reset is held low with a NC push button, pressing the button allows the pin to go high thru a pullup resistor.
 
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Audioguru again

Joined Oct 21, 2019
1,304
Mr. Guru, you do know that's a sim...right?

In an actual circuit I wouldn't recommend using a single resistor to limit the LEDs, with open collector outputs...ok...but not with CMOS outputs.
No, I did not know it is only a simulation. My LTspice schematic is not covered with the grid on your schematic. Your 555 is powered (backwards) and has power pins but the 4017 is not and does not.

Did you find the problem causing your sim not to work?
 

Audioguru again

Joined Oct 21, 2019
1,304
With only one resistor to ground shared by all the LEDs then all the LEDs that are turned off get more than their absolute maximum allowed reverse voltage of about 5V by the LED that is turned on.
I have had LEDs reverse-biased by only 3V actually lighting and needed a series diode to stop the lighting.
 

eetech00

Joined Jun 8, 2013
1,869
Hi. I just want to prepare a led roulette circuit. I set it on some programs to make sure it works correct. But it doesn't work at all. What's wrong with it? Looks like it should work shouldn't it?

View attachment 201205
I don't know the program you are using but I think you have to have a ground somewhere for the simulation to work(?)
Try adding a ground connection to the negative side of the battery,

BTW- are those two batteries, or one battery?

eT
 

AnalogKid

Joined Aug 1, 2013
8,384
I don't know the program you are using but I think you have to have a ground somewhere for the simulation to work(?)
Agree. Even though all visible return paths are connected explicitly, there still need to be Vcc and GND named nets for the phantom connections to logic chips that have power pins suppressed.

ak
 

Audioguru again

Joined Oct 21, 2019
1,304
The battery is still shown connected backwards. Its long line is its positive that should connect to Vcc. Its short line is its negative that should connect to GND.

Does your Sim program know what is inside the box labelled "NE555"? Does the NE555 have an output signal?
 

dl324

Joined Mar 30, 2015
10,536
I have had LEDs reverse-biased by only 3V actually lighting and needed a series diode to stop the lighting.
Must be some cheap Chinese LEDs.

I did a test of 10 LEDs I had laying around; all were standard brightness. 7 were OSRAM LYK376 that have a maximum reverse voltage of 3V and the rest were misc (1 OSRAM, 1 Liteon, 1 unknown). I reverse biased them at around 13.5V and I could only detect light being emitted by the Liteon.

My HP reference attributed LEDs in a matrix emitting light when they weren't supposed to be were caused by leakage in another LED. But, it also said that LEDs don't emit light when reverse biased.

I remember seeing one other LED emit light while reverse biased. It was when I was teaching my son about LEDs, diodes, and a curve tracer. He has that one (somewhere); now I have one known to emit light under reverse bias.
 
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jbeng

Joined Sep 10, 2006
72
Here's an edit of your circuit. Note the changes in the connections of the resistors to the 555. Also, I reversed the polarity of your battery & show the power and ground pins for the 4017 (even though they're probably implied by your sim program). With no LEDs connected to Q8 & Q9 of the 4017, no LEDs will be lit during the times those outputs are active.
In practice, this 555 configuration has always worked for me. Some will say that pin 5 of the 555 should have a 0.01uF capacitor to ground, but for general use, I've not found it to be required.

IMG-20200311-WA0009_edit.jpg
 
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ElectricSpidey

Joined Dec 2, 2017
1,070
The 10k VR is fine like that in a sim, but in real life you can create a direct short between VCC and the discharge pin.

"With no LEDs connected to Q8 & Q9 of the 4017, no LEDs will be lit during the times those outputs are active."

Yea, Q8 should be tied to the reset pin, good catch.
 

Reloadron

Joined Jan 15, 2015
5,363
The circuit was taken from here.

While I hate reading right to left the circuit should look like this.

4017 Roulette.png

Most roulette schemes I have see use a button that produces a burst of pulses on the 4017 Clock Input which slowly decays like a roulette wheel slowing down. About all the above is would be a basic LED Chaser using a 555 clock to drive a 4017 decade counter divider.

Here is another one using all 10 4017 outputs and at least this one reads left to right. :)

4017 Chaser Ckt.png

Now, if your circuit fails to work compare your wiring to the first image wiring I posted but something is wrong and with circuits like this threr really isn't much that can go wrong when wired correctly.

Ron
 
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