Using shift register/counters in a circuit, urgent help needed

Thread Starter


Joined Dec 11, 2006
I am working on project and am having issues getting it to work. I need to design a circuit that does four things:
1) debounces two input switches,
2) lights one led, two leds and then clears on the third press of the first pushbutton,
3) the second push button lights one led, then 2 leds, then a third LED and clears the lights on the fouth press
4) Whichever input reaches its reset point first, it clears the lights for both pushbuttons. (Its just for couting balls and strikes to make it more clear, no outs or anything)

I am just running into a brick wall with getting this to work. I have the debounce designed. Put I have tried a couple of different variations on using registers to get the lights to work and I cannot get it to. Plus, I am running into the 25 component limit on the multisim we have. I am looking at using 74175s or 74195s for the counting sections, but I am stuck. If anyone could give me some pointers on designing this and getting under the 25 component limit I would be forever grateful. The pushbuttons are being used for the clock triggering.

Here is the circuit I have so far:

I have no LEDs for the balls one b/c I am out of components to add the resistors and LEDs for it.
When I run this, LED 1 lights automatically, which I am not sure why b/c I haven't triggered the clock yet. I am basically using the 74175 to make a shift register. But I know I am messing something up in my implementation.

Thread Starter


Joined Dec 11, 2006
Ok made some progress. The strike counter section now works, sort of. It will sometimes let me go through the cycle, push button, LED1 lights, push again, LED 2 lights also, Push again, they are cleared, and push again LED1 lights again, etc.

However, about half the time I get no response from the push button. Or it lets me do the cycle a few times and then stops working. Which makes me think my debounce circuit might not be working right, but I am not sure. The second pushbutton, which will be powering the ball LEDs, if I could add another six parts on the circuit, has the same oddness to it. It will sometimes clear all lights on four presses.

I still am having problems with the parts limit. I should be able to fit it within the 25 part limit constraint, but I don't know how.

Here is my current circuit in larger size.


Thread Starter


Joined Dec 11, 2006
Ok here is the circuit with all the lights and everything. Figured out how to get past the 25 component limit. I still have problems with the buttons not working most of the time. Occasionaly I get lucky and can run through the sequence, but most of the time the buttons will only activate a light or two and quit working. Then if I hit it a bunch of times the next light might trigger. Have not been able to make all the lights activate to check if a full count clears in the correct manner on 3 strikes or 4 balls.

Here is the circuit again. In 1024 by something and 1280 by something to maintain the aspect ratio. Imagevenue shrinks the pictures once they fully load. Just click it to make it large again, in case that has been the problem.



Just in case those are still to small. Here it is giant size.



Joined Apr 26, 2005

I don't know what is going on, but it hasn't become readable yet.

Can you print it to a pdf file and then attach that file here at the forum? If you don't have a pdf distiller, I'd recommend you get the free one at


Joined Dec 7, 2006
Everyone who can't see the big images - you have to click on the small image, it's a thumbnail.

Quint -

I'm not entirely sure what the purpose of the 555's are. If they are part of the debounce circuit then ok, if not get rid of them and route the debounced output straight to the clock input.

I did a basic logic level diagram to illustrate. Otherwise, I can't see anything glaringly wrong.