40110 counter build - weird display problem

Thread Starter

fugoohomer

Joined Apr 1, 2014
3
Hello there experts,
I have a question regarding my 2 digit up/down counter using 40110 IC and NE556

I have used a 5 metre roll of 12volt led strips to make my 7 segment number display. Each segment is a 6 led/10cm strip (needed 30cm high numbers)
Power is a 12v Battery ( the ones used for battery backup in alarm systems)

I built the circuit on a breadboard tested it and counting is perfect.

I then built the circuit with IC Sockets on a Vero board, counting is again perfect however the segments do not turn off fully during counting.
ie the "off" segments are dimmly lit.

I transfer the 40110, 556 ICs and the 7 segment display back to the breadboard the segments turn off completely. So I transfer the 40110, 556 and 7 segment display back to the vero board and the segments again dont turn off completely.

Is there any reason why this is happening? I'm stumped
:confused:
 

Thread Starter

fugoohomer

Joined Apr 1, 2014
3
I built the counter off the following circuit diagram (40110 counter circuit.jpg)

Circuit built onto Vero Brd (40110 Counter - Vero brd.jpg/40110 Counter - Vero brd under.jpg)
It is replicated exactly off my breadboard build.

If the bread board had floating inputs same as the Vero board I would of thought it would show the same symptoms, yet it doesn't.
 

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MrChips

Joined Oct 2, 2009
24,651
When you cut Veroboard into smaller pieces use a fine file and remove any copper burrs at the edges. Also go over all the cut tracks and solder joints with a magnifying glass and make sure there are no unwanted shorts.
 

Thread Starter

fugoohomer

Joined Apr 1, 2014
3
I measured with multimeter, each output pin is not shorted against the next.

So I tested my 2nd Vero board build, ( i need 2 separate counters ) and there is no problem with the segments being off completely.

The only thing i can see is the 2nd vero board build does not have as much solder as the first. (the 1st build i was using a different soldering iron with a thicker tip)

Could the amount of solder between each pin be causing some type of capacitance effect ?
 

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