modifying an Electronic dice

[electronicstudent]

Hi,
i am currently working on a project where we have to implement an electronic dice like on this webpage http://www.kpsec.freeuk.com/projects/dice.htm

this part was ok but then we also have to modify it to make the circuit operate in a counter mode, such that each time the switch is pressed the number is incremented by 1.In other words, starting from 1, the sequence will be displayed 1,2,3,4,5,6 each time the switch is pressed.
urgently need help for 2nd part. :s

 

[(*steve*)]

I presume this is a school project of some type?

You need to understand how the dice circuit works.

Then you need to figure out what to change in order to make it perform the new function.

So, what is your understanding of the circuit?

You may need to google some datasheets if you're not instantly familiar with the 555 and the 4017 chip.

There is a sticky thread in the datasheet part of these forums which explains how to look for them, but just googling for the part number and the word "datasheet" is a very good start.

 

[electronicstudent]

yes it is a school project and yes i already googled the datasheet.

i know that the 555 timer can be in the astable,monostable, bistable state. but for this case it is in the astable state which gives a square sine wave signal.

the 4017 IC is a decade counter which goes high for 0-4 and low for5-9.

the RESET output is connected to output 6 so that it resets the counter when the dice shows 6.

diodes are there to prevent current from going to other outputs.

i think that this i as much that i understood... i dnt knw if i just need to change the connections to the 4017 IC or use another counter.. or switch the 555timer state to monostable...

:s any help? :s

 

[(*steve*)]

That's a pretty good explanation, certainly far better than we often get from students. Good work!

Your description of the decade counter is a little off. However the usage in this circuit is particularly tricky, using the carry output in a very unconventional manner.

Also check how (and when) the 4017 reset. Is it reset when the dice shows 6, or after the dice shows 6? (this is actually a very tricky question because the answer is "neither"). Read the description of where the count starts! If the outputs are 0 to 9, yes, there is something special about 6, but it's neither the 6th count or 6 showing on the dice, it is something else...

Using a monostable instead of an astable is a great idea. But look at how the counting is controlled now. What will you need to change to make it work? And what about the time period of the monostable compared with that for the astable?

 

[electronicstudent]

ah.. the reset should be connected to output 7 so that the instant output 7 goes high (that is after dice shows 6) , the counter is reset and counting starts again...

time period of the monostable will depend on only a resistor and a capacitor whereas for the astable state it depends on 2 resistors and 1 capacitor.

maybe invert the divide by 10 output?
increase resistance/capacitance to increase period between each pulse so that we can actually see the dice going through 1,2,3,4,5,6. because for the original circuit it goes so fast that we only see the random ouput....

ahh think i need some help here :S