What's wrong?

dl324

Joined Mar 30, 2015
10,467
Image for those concerned about opening PDFs.
1585170127348.png
EDIT: The open mentioned in post #7 was due to over aggressive brightening by me. The correct image is in post 35.
 
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dendad

Joined Feb 20, 2016
3,425
Do you have any bypass capacitors on the power supply?
One 100nF across the power pins at each IC for a start. I often use sockets and place the cap inside each socket so the leads are as short as can be. Then a couple of 10uF Tantalum caps on the power feed as well.
Also, how is it all constructed?
 

Thread Starter

Arjune

Joined Jan 6, 2018
122
What is providing the clock pulses?
I have included the modulus 60 counter which is for minutes and there is another one for seconds attached one after the other. I got the 1hz pulse from a wall clock that drives a couple of transistors. A 555 timer astable oscillator set to about 100hz is used at the seconds input to set the clock.
 

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jbeng

Joined Sep 10, 2006
72
I see an unconnected (floating) input, a big no-no in the world of cmos. If it's really like that, it could be contributing to your problem. Maybe it's just not connected on the drawing?

1585170127348.jpg
 

Thread Starter

Arjune

Joined Jan 6, 2018
122
Do you have any bypass capacitors on the power supply?
One 100nF across the power pins at each IC for a start. I often use sockets and place the cap inside each socket so the leads are as short as can be. Then a couple of 10uF Tantalum caps on the power feed as well.
Also, how is it all constructed?
I use a regulated power supply at about 5.5 volts DC and I don't think I need bypass capacitors. I think I do have a 470 microfarads bypass capacitor at the output of the power supply but I'm afraid that that could go back into the regulator and destroy it if I remove the power from the line. I would have to check to be sure. The circuit is constructed on circuit boards in a plastic case, the seconds is in the back of the case, I will attach a picture.
 

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Thread Starter

Arjune

Joined Jan 6, 2018
122
I see an unconnected (floating) input, a big no-no in the world of cmos. If it's really like that, it could be contributing to your problem. Maybe it's just not connected on the drawing?

View attachment 202394
I am sure when I submitted this post that connection was there. I think it has to do with the paranormal or aliens trying to determine something that they do not understand. I think I'm also dealing with the influence of the devil. I am not being sarcastic or rude. Since you brought that up I am thinking that a wired connection may have an illusion that it exists and it may not in the circuit somewhere.
 

MrChips

Joined Oct 2, 2009
20,859
We've said this too many times before:

1) 0.1μF ceramic capacitors across Vcc and GND are required. This is not optional.

2) Once you drive an LED directly from an output pin you cannot use this output as a valid logic state.
 

dendad

Joined Feb 20, 2016
3,425
and I don't think I need bypass capacitors.
Yes you do!
The ICs are switching at a fast rate and a few inches of wire is significant.
It is good practice to add a bypass cap at each IC. Yes, you can put more bypassing on a circuit that is really needed, but more will not hurt. Too little can cause all sorts of funny problems.
So, get into the habit of soldering a bypass on each IC. You can add them on the bottom of the PCB from the +5V to the GND pins of each ID. Particularly those that are switching. A good clean power supply is the best foundation of any circuit. If you get ground bounce or Vcc sag as they switch, there will be problems.

EDIT: Ah! Onnce again you beat me @MrChips :)
 

Thread Starter

Arjune

Joined Jan 6, 2018
122
We've said this too many times before:

1) 0.1μF ceramic capacitors across Vcc and GND are required. This is not optional.

2) Once you drive an LED directly from an output pin you cannot use this output as a valid logic state.
Mr. Chips I get the message that the circuit design is functional since you didn't contradict my design. So then I'll order the .1 microfarad capacitors but I don't know if they can process this with coronavirus. I see that you can get 10 for less than $3 on eBay. I do believe that the devil is causing transient activity in the circuit to cause a miscount so that he can get a heads up over time. I understand if you cannot acknowledge that because it is not verifiable. CMOS devices use low current so I don't think there would be a transient fault. Correct me if I'm wrong. I should also add that the LEDs do not exist at the outputs of the CD 4510 and it is only there for my understanding. I know the load current capability is very low. Be well sir.
 

dl324

Joined Mar 30, 2015
10,467
CMOS devices use low current so I don't think there would be a transient fault. Correct me if I'm wrong.
In CMOS gates, there's a short time when both P and N devices are conducting. This can put noise on the power supply. The decoupling capacitors are used to filter out that noise.
I should also add that the LEDs do not exist at the outputs of the CD 4510 and it is only there for my understanding.
You can leave them in place if you increase the current limit resistor. Since most CD4xxx outputs can only source about 1mA at VCC=5V, making the resistors 10k should give enough light to see without loading the outputs.
 

dendad

Joined Feb 20, 2016
3,425
It is interesting that you are asking "Whats-wrong" and when a number of us say "add bypassing" you are arguing against that.
It is like trying to build a house without a foundation. It may work, if you are lucky, but it is not the way to go.
The board's power supply is the circuit's foundation and if that is suspect, well.....
 

Thread Starter

Arjune

Joined Jan 6, 2018
122
It is interesting that you are asking "Whats-wrong" and when a number of us say "add bypassing" you are arguing against that.
It is like trying to build a house without a foundation. It may work, if you are lucky, but it is not the way to go.
The board's power supply is the circuit's foundation and if that is suspect, well.....
My mind is not on a firm foundation because of my schizophrenia. I don't trust the truth of reality because it is meant to hide the spirit with theory. I'm arguing because you don't recognize my diagnostics mode.

Anyhow I was wondering if the cd4511 decoder and display drivers could be at fault because I did not bypass those IC on the power pins. I would believe that that is the source of the problem since they use more current to drive the displays as compared to the logic gates or the cd4510 counters. The 4511 would have more transient current surges wouldn't they?
 
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dl324

Joined Mar 30, 2015
10,467
Anyhow I was wondering if the cd4011 [sic] decoder and display drivers could be at fault because I did not bypass those IC on the power pins. I would believe that that is the source of the problem since they use more current to drive the displays as compared to the logic gates or the cd4010 [sic] counters. The 4011 [sic] would have more transient current surges wouldn't they?
That wouldn't cause the count on the hours counter to change.

You have typos in the counter and decoder parts. If you correct them, you won't have others pointing that out.
 

Audioguru again

Joined Oct 21, 2019
1,259
The devil and aliens are making sure that your 50 years old (!) 555 oscillator overloads the 5.5V supply with its 400mA supply current pulses each time the output switches. Instead a Cmos 555 clock oscillator should have been used.
 

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