Naked Science Forum
Non Life Sciences => Technology => Topic started by: Cody on 20/01/2011 03:30:04
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Cody asked the Naked Scientists:
how does the game "Operation" work?
Cody
What do you think?
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Basically, the game works by creating a simple circuit. The battery, light, buzzer, metal edges on the body and metal tweezers are connected by wires yet the wires do not go in a full circle. ie. imagine that each part is like on a chain yet it wont work unless the chain is done up and goes in a full circle. This is called a complete circuit. To complete the circuit the metal of the tweezers must touch the metal edge of the body. This connection works the same as a switch would in a simple circuit such as turning on a light. When the circuit is complete the light and buzzer turn on from the power in the battery. However, if the circuit is not complete this can't happen.
Hope this helps.
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To complete the circuit the metal of the tweezers must touch the metal edge of the body.
This connection works the same as a switch would in a simple circuit such as turning on a light.
It's a long time since I played operation, but isn't there a latch circuit (http://en.wikipedia.org/wiki/Latch_%28electronics%29) involved:
even though the metal-metal connection may only be made momentarily the buzzer and light stay on until reset.
I may be wrong, like I said it's been a long time.
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I think you are right. Here's a simpler version -
[diagram=620_0]
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A couple of 555 timer (http://en.wikipedia.org/wiki/555_timer) circuits would do it : one to make a latch (http://www.kpsec.freeuk.com/555timer.htm#bistable) and one to make a buzzer (http://www.kpsec.freeuk.com/555timer.htm#astable).
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My "drawing" is a latch
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My "drawing" is a latch
The block diagram symbol for a latch is a rectangle: here is the RS latch in the 555 timer IC (http://en.wikipedia.org/wiki/555_timer) (coloured) ...
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More (rectangular) latch symbols here ... http://en.wikipedia.org/wiki/Flip-flop_%28electronics%29#Implementation
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Geezer's diagram, while spectacularly unclear, is a latch.
Perhaps more importantly, I think that game might have been going longer than the 555.
If so, I wonder what the original electronics were.
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I wonder what the original electronics were.
Could be made with a pair of transistors ... http://en.wikipedia.org/wiki/File:Flipflop_by_trexer.png
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Pretty much anything with more than unity gain could be used. That might be a couple of transistors, a relay, or a non-inverting logic buffer.
However, I have a vague recollection that the buzzer sounded for a bit, then shut itself off. If that's true, then a latch won't quite hack it. We'll need a monostable of some sort. That could be done with some sort of resistor/capacitor network to produce a time constant, combined with a couple of transistors, a relay, or a non-inverting logic buffer.
As relays tend to be a lot more expensive than transistors, I'd think it's most likely they used a couple of cheap transistors.
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With lots more detail.
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