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Game-buzzer setup

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IamSmooth

Wed May 23 2007, 01:41PM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

We were playing jeopardy at work and had to resort to someone ringing a bell at their tabe. Does anyone have any ideas how to setup a simple buzzer device that will allow only one of three buttons to turn on a light and lock-out the other two? There would need to be a reset switch to re-enable all three.

I've started thinking about it and I guess I would have to setup some logic probably with flip-flops and the output from the designated table would activate a SCR to turn on a light. It is the logic part that I could use some suggestions.

EDIT:
After an initial search I found some suggestions. Here is one article with some ideas:

I was wondering what others thought as the best approach. Would logic circuits be overboard? Simply using SCRs seems like a quick solution.

Part Scavenger

Wed May 23 2007, 04:04PM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I built one for the nursing school. I'll see if I can dig up some info for you when I get home. I have the original schematic from an issue of Popular Electronics and one I modified and build. It has been working fine for over a year, I've even still got the PCB file for ExpressPCB. In fact, I posted the schematic somewhere on this forum if you want to go find it.

It was real easy, just bunch of SCRs, resistors and a relay run by a 555 and a 2n2222 to reset the SCRs...

Ok, looked at the site, my design didn't have "contestant stations" just a pipe bomb style handheld button. We got some rubber bicycle grips and jammed PVC pipe up their rear and put a nice red Radio Shack button on top, then we used RCA cable to connect to the unit. It looked very professional.

I'll see what I can dig up when I get home.

Bjørn

Wed May 23 2007, 05:32PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

I suggest using relays, a single relay can replace a lot of transistors and logic gates depending on how many sets of contacts it has. Grown-ups playing Jeopardy with some dinky flip-flops does not sound right to me.

ConKbot of Doom

Thu May 24 2007, 01:15AM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
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Posts: 329

BjÃ¸rn BÃ¦verfjord wrote ...

I suggest using relays, a single relay can replace a lot of transistors and logic gates depending on how many sets of contacts it has. Grown-ups playing Jeopardy with some dinky flip-flops does not sound right to me.

Relays would be pretty good for that, just some 4PDT relays would work fine. 1 set of contacts to latch the relay on, and 1 set for each other buzzer, and one for the light. I would avoid latching relays, since you could run into a situation where somehow two people hit the buzzer at a close enough time, that they both ring in and kill the power to each other, and either both or neither ring in.

IamSmooth

Thu May 24 2007, 02:26AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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How would relays help? If the contact is made to complete the magnetic circuit within the relay, what prevents another relay from activating?

Bjørn

Thu May 24 2007, 02:34AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

You connect it so it disables the other relays. At one time it was common to make computers out of relays so anything you can do with a PC you can do with relays. It will just take a bit longer.

IamSmooth

Thu May 24 2007, 02:49AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
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Posts: 1567

I found another version with the SCRs

Part Scavenger

Thu May 24 2007, 03:04AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Here's the circuit, as promised. Seems like I got rid of the 4017 'cause it wasn't worth it in shipping and used a monostable 555 and a transistor for "K2." I had quite a bit of trouble getting the SCRs in a small package so I used larger ones, just make sure you put enough current through them to keep them on. I also amplified the output of U3 so that you could hear it loudly in our noisy classroom. I wish I had pics, it was BEAUTIFUL, oak box and the first panel I made I would consider "nice."

EDIT: Well crap beans! Why doesn't the resizer work anymore? */Digging out my "HTML for the galactically stupid."

IamSmooth

Thu May 24 2007, 11:49AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

Thanks a lot. Now I have to decide how nice to make it look.

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