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Need 6 channel digital input to PC

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iwonder

New Member
Hi, i am at a loss after having scavenged the net for hours without finding any precise answers for this.
I have been asked to program a PC based scoreboard for Tae Kwon Do competitions which I will do in VB.
I need to register the 3 judge's inputs in this manner:
each judge has a hand control with two buttons - one for each contestant.
In order for a score to be registered, at least two of the judges have to push the same button within 2 seconds.

I was thinking that RS232 seems to be leaving the world of laptops, so parallell or USB (or USB via a port replicator) would probably be the way to go.

I am familiar with assembling electronic circuits, but not designing them so I was hoping maybe someone here would help me out...


Best regards
Jens
 

Russlk

New Member
My solution is posted below, you don't need the PC.
 

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iwonder

New Member
Hi, thank you for your reply - the solution was really neat, but I am afraid I need the PC anyway since I have to make a transcript of all activity, ie. for every point given, I have to record what vote was given by each judge. In addition there is a judge out on the mat giving out warnings and negative points by hand signal and these have to be recorded by an operator on the PC. One more (and the main) reason is that I want the score presented by a projector on a large screen for the audience to see.
This is all to replace the manual system of flipovers used today, which has a significant delay so it is hard for the audience unfamiliar with the sport to actually see which hit gave a point.

I hope I didn't leave out too much this time.

Best regards
Jens
 

Roff

Well-Known Member
I suspected you had a multitude of reasons for needing to use a PC. I'm sorry I don't have any answers for you. I agree that Russ's solution is neat, but I think he designed that circuit when he was tired, and a few errors crept in. For the sake of someone else who might want to use it, or wants to analyze it as an intellectual exercise as I did:

1. The NOR gates need to be changed to NAND gates.
2. The intermediate 3 input NAND is not needed.
3. The top NAND on the latch needs 4 inputs. The bottom one can be the remaining one from either package.
4. The high output is from the top of the latch, not the bottom.
5. The time constants on the monostables are 2ms. They should be 2 seconds (actually, 1.82 seconds).
6. The judge must release his button before the 2 seconds is up (fairly likely, but differentiators would solve this potential problem). I didn't add these.
A revised schematic is posted below.
 

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