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Help! Scorer?

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The long explanation... Skip this if you are easily bored!
I'm a teacher who decided to go teach in another country. Hey why not? Paid Holiday. Hell yes!
I arrived at my new job to find out I'm now teaching 2 year eleven electronics classes. Only one problem.... I have never taught electronics before. I've never even studied electronics before! So I have been on a very steep learning curve. Don't worry I know manage to work out which part of a component is positive and which is negative 50% of the time. So I think I'm basically an expert now. I just have a few problems. One half my students know more about electronics than I do and two they still don't have much of a clue either.
Please help. It's for the children!

Short explanation...
I need help designing a scorer. Like you would use to keep score of a snooker game electronically. I was trying to use a 4510 bcd counter and 4511 decoder with a 7seg counter. It works fine when I model it in the school's prehistoric version of crocodile clips but when I build it. It doesn't work unless I create an astable circuit to create pulses for the clock input.

Has anyone got a schematic for a scorer? There are heaps of schematics for electronic dices out there but none for scorers.
 

audioguru

Well-Known Member
Most Helpful Member
The switch makes many bounces of its contacts each time it is pushed. The counter counts them all.
You need a "debounce" circuit for the switch. Look in Google.

Poor kids having a teacher that doesn't know the subject. Can you speak their language? My teachers couldn't speak my language and also didn't know electronics.
 
Yeah I feel so guilty... but what can I do? It's the school's fault. At least I speak the language so that's okay.

If the problem was too many pulses wouldn't it still count but just not in order. When I build it, it doesn't count at all. At least it did when I tried it with a 4017 decade counter and ten LEDS. Pin 1 just stays lit the whole time.
 

audioguru

Well-Known Member
Most Helpful Member
If the switch pullls the clock voltage high then a resistor to ground must be there to pull it low when the switch is opened.
 

AllVol

New Member
You really do need to debounce your mechanical switch. Also a hefty bypass capacitor or two will help. Google for these topics.


To answer your question, yes each rapid contact of the switch is counted; so fast, in fact, that you'll never know how many counts were recognized.
 

audioguru

Well-Known Member
Most Helpful Member
A 1k resistor is a low value for a Cmos input that draws no current. The current in the 1k resistor wastes battery power. Use 10k or 100k if the switch has gold contacts.

Pin 15 on a 4017 is its Reset pin. It must be at 0V for it to work.
 

Hero999

Banned
Is this just a simple counter or does it take into account for the different coloured balls being worth different scores?

Could you please post the schematic.

Are you also aware that each IC needs a 100nF capacitor in parallel with the power supply to work properly?

Does it have a power on reset?
 
Schematic

Okay hopefully I've done this right. There should be a schematic.gif attached to this reply.

The top picture is how I had the 4017 wired up as a demonstration for my students. I had a 555 astable creating the pulses.

The second picture is how I tried to set it up so I could use it as a counter. I added the 10k resistor on pin 14 after some advice from audioguru.

The next stage I plan to do is to use a 4510 bcd counter, 4511 decoder and a 7seg display. I haven't built this yet as I am still waiting for the chips to arrive but I am worried now by the fact that the 4017 didn't work as I expected from crocodile clips.

I also need at some point to make the circuit work for different inputs (for different coloured balls) however I haven't really been thinking about that yet. I just want to get the simple one working. Counter.gif

I should add that my students are not that advanced and most of them spend there time trying to vandalise my classroom when I'm not looking but still some of them are trying so hard.

Oh and thanks heaps for all your help.
 

audioguru

Well-Known Member
Most Helpful Member
The clock switch or "coloured ball detector" definitely needs to have "a debounce circuit" added to it.
 
I'm a little confused I must confess about the 100nF capacitor in parallel to the power in each IC. Especially when it becomes time to try the 4510, 4511, 7seg combination.

Does that mean I need 2 capacitors parallel to where I connect the battery pack...

Or do I somehow connect the capacitors in parallel to the actual chips' power pins?
 

Hero999

Banned
Connect a capacitor in parallel with each chip's power pins. This is called supply decoupling; the capacitor supplies power when the IC draws a high current for a sort period of time.
 
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