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Dice Project - 4081 AND Gate Help

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Hiredman

New Member
Hello All,
I'm working a breadboard version of a multi-sided dice roller replacement and I'm mostly there but now I'm stuck.

What works:
I currently have a 555 feeding clock to a 4029 which feeds a 4511 driver to a 7 segment LED which works fine as a repeating 0-9 counter. To replace a die I need to preset the 4029 to start at "1" (that's why I'm using the 4029 with preset) which I've gotten working by taking the all the non-1 inputs low and the 1 input high. When I hook up the 8 count pin directly the counter runs 1-7 and resets correctly.

What doesn't:
I wanted to use a 4081 AND gate and a switch to decide the "top" number of the die that was 'rolling'. For instance I thought I could combine the 8 and 1 outputs and take the output from that gate and feed back to the 4029 reset and make the system choose between 1 - 8 on a roll by resetting on '9'. But using the AND gate outputs have been unpredictable - sometimes the gates seem to fire at the wrong times - sometimes they seem to "skip" the reset number on the LED. I have the feeling that the AND chip is taking the counted number low and not behaving as I thought it would. When I hooked up and LED to the AND output I'm not seeing it go high but the 4029 still resets (at the wrong number).

Ultimately I was hoping to feed the AND gate outputs into a switch and decide between 4,6 and 8s but resetting on 5,7 and 9 respectively. Does this seem do-able or is my understanding of the 4081/4029 interaction off?

Thanks - all thoughts welcome,
=Tod

PS Eventually the 555 will have a "roll when pushed" button set-up but it currently just running when powered on.
 

Hiredman

New Member
I didn't get any responses to my initial question so I thought some diagrams might help.
Here's the base circuit that works as expected - it starts at 1 and if I hook up one of the outputs - like 8 - it counts to 7 and starts over at 1.

9357-Sketch_orig.jpg


But I want it to count 1 - 8 so I thought I could simply add a 4081 2 gate AND and attach the output from 1 and 8 to the in AND and then take the AND output to reset to get 1 - 8 counting.

9358-Sketch_4081.jpg


But when I do this with two gates like the 4 and the 2 instead of counting to 5 it usually counts 1-3 just like the 4 output is attached. What's odd is if I attach a common cath LED to the AND output (as shown in the sketch) it doesn't light but it it will start counting correctly.

Is there something I need to do to make the AND gate work for the reset? What would that be?

Thanks!

=Tod
 

mbarazeen

Member
whay dont you try a manual imput to 4029 and observe, instead of 555 input, just put a bompless switch and give clock by pressing it, so you can easily observe the state changes by connecting LEDs at required point. you said you couldnt see the LED connected to the reset blinking, it may be because of you fast clock.

have a try as i said and see how your 4081 responds. if you have connected everything as you explained it should work wihtout any problem.

also check for any poor connection on the breadboard.
 
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