3-Digit Counter

Thread Starter

maker_2023

Joined Nov 20, 2023
167
Hi:

I have breadboarded a digital counter circuit. I added a hundreds digit and it doesn't
do anything although the units and tens digits work and the counter counts up to
99. I have checked the wiring and I believe that it is correct as it is identical to the
tens digit stage. I have also swapped out the hundreds digit ICs with the tens digit
ICs and they work. I am at a loss as to what the problem could be. I would appreciate
some help.

I have attached a photo of the circuit and a schematic of the 2-digit version (the third
digit is identical to the second).

Thanks,

M
 

Attachments

Thread Starter

maker_2023

Joined Nov 20, 2023
167
hi maker,
As a test, does any segment on the 100's light if you move the Yellow wire [arrow end] to +5V?
E
Hi E

I checked each segment and they all light. Yesterday, I also swapped the 10's chips with
the 100's chips and the counter still counted to 99 so I guess the chips are ok. I should
also mention that I removed all segment connections but one just for clarity when taking
the photo.

M
 

ericgibbs

Joined Jan 29, 2010
18,827
Hi,
For debugging, try feeding the Units clock directly into the last decade, ie: 100's logic.
Use the yellow wire that drives one segment as a probe to trace the progress of the clock through that part of the logic., do you follow OK?
E
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
Hi,
For debugging, try feeding the Units clock directly into the last decade, ie: 100's logic.
Use the yellow wire that drives one segment as a probe to trace the progress of the clock through that part of the logic., do you follow OK?
E
I will try that.
 

ericgibbs

Joined Jan 29, 2010
18,827
Hi,
A handy debugging circuit is a simple single LED with a 1k series resistor.
LED Anode to 0V and the high side of the 1K with a wire for probing the circuit.
E
 

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MrChips

Joined Oct 2, 2009
30,780
Hi:
I have breadboarded a digital counter circuit. I added a hundreds digit and it doesn't do anything...
You are doing it again - "it doesn't do anything"
What is that suppose to mean?
Do any segments light up?
Have you done the LAMP TEST by connecting pin-3 of the CD4511 display/driver to GND?
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
I will try that. It didn't work.
I found that the area of the breadboard where I had the display, is no good.
When I moved the display to the bottom of the board, it displays a "0".
It still does not count. I am surpised that the breadboard is defective as it
is brand new. Sad thing is, I bought three of them.
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
You are doing it again - "it doesn't do anything"
What is that suppose to mean?
Do any segments light up?
Have you done the LAMP TEST by connecting pin-3 of the CD4511 display/driver to GND?
It displays a zero for the hundreds and counts to 99. I did mention that in my 0 - 9 counter post earlier but I got no response
so I created a new post and forgot to say that this time. But it does not count.

As the circuit stands now, if I connect pin 3 of the hundreds CD4511, it displays an "8".
 
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Thread Starter

maker_2023

Joined Nov 20, 2023
167
No D,C,B, and A are at logic zero. The counter is not counting. Is it possible that the oscillator
just doesn't have eough drive for more than two counter stages? I remenber when I tried to
drive a small LED off the oscillator as a pulse indicator, the counter wouldn't count at all.
 
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MrChips

Joined Oct 2, 2009
30,780
No D,C,B, and A are at logic zero. The counter is not counting. Is it possible that the oscillator
just doesn't have eough drive for more than two counter stages? I remenber when I tried to
drive a small LED off the oscillator as a pulse indicator, the counter wouldn't count at all.
The problem is not clock loading. CMOS gates take very little input current.
Check and double check your pins and wiring on the CD4510. I have seen people insert ICs into breadboards and a pin gets bent unseen underneath the IC.
 

Thread Starter

maker_2023

Joined Nov 20, 2023
167
The problem is not clock loading. CMOS gates take very little input current.
Check and double check your pins and wiring on the CD4510. I have seen people insert ICs into breadboards and a pin gets bent unseen underneath the IC.
Hi:

Checked them. Pins are ok. I have checked the wiring multiple times and even re-wired multiple times.

After making no changes I powered the circuit up again. Now the hundreds displays a zero while the
counter counts to "99". When it hits "99", the hundreds digit blinks but continues to display a "0". The
counter counts to "99" again and then the hundreds digit blinks an changes to "1". Then at some point
the hundreds digit reverts back to a "0".
 
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