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Stupidly simple circuit question - answered. Answered

OK, so I accidentally volunteered to make an X-factor type buzzer board for a school event.

Three switches.  Throw each switch, in any order, a light comes on.

Throw the third switch, in any order, and a buzzer and/or fourth light comes on.

It's a simple circuit.  Must be.  Just a few transistors, LEDs and batteries.

But, I just cannot work it out!

I should be able to sketch it out in my sleep, but my brain will simply not cooperate.

I'd prefer to use a single DC power supply, up to 12V (multiple LEDs to make the lights brighter), but I have several I can use if required.

Dimensions are not important, I'll just change the lengths of wires.

But, can you help with the circuit?

>K<

Thank you, Lemonie!




33 Replies

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lemonie (author)2010-01-02

Right, I've never watched X-Factor, but I think you want:
Each of three switches to light their own light independently.
All three switches to power a buzzer / 4th light?
Get three double-pole double throws, and wire like this.

L

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Lithium Rain (author)lemonie2010-01-02

>gives lemonie a vicious kick for coming up with a better idea and schematic before I was about to post another<


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Kiteman (author)Lithium Rain2010-01-02

I was all ready to go for a set of self-latching relays...

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Lithium Rain (author)Kiteman2010-01-02

I made it all pretty, with a three way AND gate and everything.

>mourns<

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Kiteman (author)Lithium Rain2010-01-02

Hey, you can still post it, especially if it's all pretty.

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Goodhart (author)Kiteman2010-01-04
I have to agree with Jayefuu here too;  without something like a 555 timer, you will have to reset the buzzer manually, or reset everything to cut the buzzer, since it is latching. 

If the switches trip the timer (monostable multivibrator) which trip the buzzer, you can set the duration of the buzz time.
 

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Jayefuu (author)Kiteman2010-01-02

Don't forget a monostable otherwise that buzzer's going to be going off FOR EVER and be really annoying :D

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whatsisface (author)Jayefuu2010-01-03

That's a very good suggestion.

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lemonie (author)Kiteman2010-01-02

If you want something with big red plastic single-push non-latching buttons that light-up and a master-reset, the question is still open...

L

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Kiteman (author)lemonie2010-01-03

I'm now waiting to find out my budget - latching DPDT push-switches are available on ebay.


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lemonie (author)Lithium Rain2010-01-02
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Derin (author)lemonie2010-01-02

Can I recommend armor,pretty useful...

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V-Man737 (author)Derin2010-01-03

Of the pop-tab-maille variety?


(Let's have a discussion about the protective quality of aluminum as medieval armor!) :-P

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lemonie (author)V-Man7372010-01-03

That's one "age" missing from History... But the topic is around here somewhere (a person objecting to the armour on grounds of irresponsibility)

L

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user

Gah, beat me by 3 mins, and with a schematic too!

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user

I would have been a bit quicker, but I had to be sure of what the thing is supposed to do first...
DPDT - we think alike

L

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Kiteman (author)lemonie2010-01-02

Egad!  The man's a genius!

I could even make that with clothes pages!

I knew it was simple, I just could not make it work in my head.

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Re-design (author)2010-01-03

I just have to say that the competition is getting very stiff.  Yall make a great committee.

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Kiteman (author)Re-design2010-01-03
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Re-design (author)Kiteman2010-01-03

So many people with good answers all trying to be there first.

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Lithium Rain (author)2010-01-02

I'm a little confused by the description - you mean like this (yes,  I know it's messy, I did it in a hurry :P )?


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Kiteman (author)Lithium Rain2010-01-02

Three judges, each with a switch.

When they have had enough of a contestant, they hit a switch and a light comes on.

When the third judge hits their switch, in addition to their light coming on, a fourth event (such as a buzzer) indicates that the contestant is no longer welcome on the stage.

So - three switches, each working one light.

A fourth device gets triggered once all three lights come on (the three lights can be lit in any order).

Is that clearer?

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Rock Soldier (author)Kiteman2010-01-02

I know Lemonie already answered, but wouldn't it be easier to have switch one control a light, switch two control an other light, and switch three control a light and a buzzer? As in only switch three needs to be "switched on" for the buzzer to go off? As long as judge three goes last, it seemingly works the say way as Lemonie's suggestion.

Also, what's the school event? Talent show, spelling bee, science fair?

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Kiteman (author)Rock Soldier2010-01-02

It's a talent show, hence the X-factorisation.

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Rock Soldier (author)Kiteman2010-01-02

Ah, I see. I never watched the show, so I wouldn't know. Thanks.

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user

Need three double pole single throw switch.

Use one pole from each switch to actuate each light, connect the second pole of each switch in series to actuate the fourth light.

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user

Thanks!

Unfortunately, Lemonie beat you to it by three minutes.

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Lithium Rain (author)Kiteman2010-01-02

Ahhhh, much, yes. :D Thanks.

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lemonie (author)2010-01-02

Do you get the sense of being on the same level as students who also have homework to do this weekend before they go back...? (Like my brother who's got a load of marking to do)

I'll think

L

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Kiteman (author)lemonie2010-01-02

I've got a few weeks, but I have a terrible habit of getting distracted by new projects.  I know that I have two other large projects on the horizon, plus I have a bit of a learning curve to climb at work in the next two terms.

Oh, and there's the marking...

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lemonie (author)Kiteman2010-01-02

Marking... having a few teachers in the family: I know.

L

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Jayefuu (author)2010-01-02

Sorry, the instructables community doesn't like answering homework questions. :p

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Jayefuu (author)Jayefuu2010-01-02

Ok... so you need:

AND gates

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