Hi,

Let me start by saying that my experience with circuits is somewhat limited, but I do have a basic understanding and have taught myself how to use the Eagle design software.

That being said...

I am attempting to re-create a 30 year old circuit based on a schematic I was given. This circuit creates an oscillating pattern on a 10-segment LED array and then also is used to provide the logic for a much bigger, wall mounted halogen display.

Using a solderless breadboard, I was able to successfully re-create the circuit and it works perfectly. I then attempted to create the circuit in Eagle PCB and had some boards made. When I got them populated and powered it up, the LED array only cycled in one direction, not back and forth.

See this video for both the working breadboard and the malfunctioning PCB:

The circuit uses the following ICs:

4049 (Inverting Hex Buffer)
4510 (Up/Down Counter)
4028 (Decimal Decoder)
4013 (Flip Flop)
2804 (Driver Array)

Attached also are screenshots of my Eagle layouts. This circuit needs to be split over 2 boards.

It's obviously a problem with my Eagle design. I am hoping that someone can spot the issue, because I have gone over it many times and can't find the problem. Or, perhaps someone could at least help me figure out which IC is causing this malfunction, so I can devote my energies just to that segment of the board.

For various reasons, I cannot post the original schematic here. If someone out there truly thinks they can help and needs the original schematic to troubleshoot, we might be able to share it privately.

I am sure there are easier and better ways to design a circuit to produce the desired outcome, but for this project, the circuit design must absolutely stay the same as I have described it.

Thank you!

 

Pin 10 up/dn on IC4 is not being toggled, check for pulses from IC3...

 

Does the wiring is correct with blue color?

 

I checked on my breadboard, and I have a pulse (0V - 9V - 0V - etc) on pin 10 of IC4, but on the Eagle PCBs, it stays a near constant 9V.

Scott - I will check on that and let you know!

 

Scott - yes, that wiring is correct and connects as it should.

 

I checked on my breadboard, and I have a pulse (0V - 9V - 0V - etc) on pin 10 of IC4, but on the Eagle PCBs, it stays a near constant 9V.

Scott - I will check on that and let you know!

There you go, so check pin1 IC3, for pulses to IC4 pin 10.

 

I did that....Pin 1 IC3 also stays a constant 9V.

 

The normal wiring of blue color in my post #3 seems looks like this.

 

Check pin 3 on IC3A
Also check pin 4 on IC3A
Also check pin 6 on IC3A.

 

Pins 3,4 and 6 all pulse on the Eagle PCB, just the same as the breadboard.

 

If pin 1 on IC3 is stuck high, its either faulty or its not being clocked correctly, if the ic is in a socket, pull pin 1 out and check it to see what's happening.

 

Well, it's not faulty. I tried 3 different 4013 chips and they all produced the same result. I even tried the one that confirmed working on my breadboard.

I am going to go back to my Eagle schematic, wire by wire, and compare it to my working example. I've done that many times already, but there's gotta be something small I am missing.

 

Getting back to this...

I can't find the issue. Anyone willing to look over the Eagle schematics and find the problem? I'd be happy to pay for your troubles.

Thanks
Joe

 

Am I missing something? I can't make any sense of the circuits as shown.

 

Pin 6 of IC3A should only pulse high when power is applied to the circuit. After that it should be at zero volts.

Les.

 

OK, if the electrolytic Capacitors are installed as shown, they are installed backwards, and would present problems.

Where does JP2 (the 2 pin one, not the 11 pin one) go?

 

I did mean to say that the entire circuit did not make sense, just the 4049 clock generator part. It can never work as drawn.

Try this

 

OK, if the electrolytic Capacitors are installed as shown, they are installed backwards, and would present problems.

Where does JP2 (the 2 pin one, not the 11 pin one) go?

It goes to the potentiometer that adjusts the sweeping speed.

 

I did mean to say that the entire circuit did not make sense, just the 4049 clock generator part. It can never work as drawn.

Try this

See, that's the thing. It DOES work, perfectly, with this configuration, on my solderless breadboard.

Here's the original, 30 year old schematic. Maybe this will help.

 

See, that's the thing. It DOES work, perfectly, with this configuration, on my solderless breadboard.

Here's the original, 30 year old schematic. Maybe this will help.

So, working left to right, the ship's do the following...
==============================

Cd4049: Create pulses (rate adjusted with pot)

Cd4510: converts pulses to a 4-bit binary value (0 - 9) and sows op on the 4 output pins.
(Counts up when pin 10 is high, counts down when pin 10 is low)
(Note - this up/down pin is critical to back/forth sweep of LEDs)

Cd4028: one of 10 decoder. Takes the 4-bit binary value of cd4510 and converts that to one of 10-outputs. 10-output pins cycle with one light on at a time.

Cd4013: flip/flop is a kind of switch that toggles when the cd4510 up/down counter when the cd4028 gets to its upper or lower limit (pins 3 and 4). (Pin 1 of cd4013 is the link back to the 4510 pin-10)

2804: obviously a darlington output array to amplify current to drive relay coils.

=======
If pin 1 of flip flop is not communicating back to to the cd4510 to tell it to count down, there is trouble with the toggling circuitry. Trace back and look at the inputs of the flipflop.