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Please help with simple circuit requirements

  1. Jan 18, 2009 #1
    Hi. I hope this request is within forum rules. I couldnt spot anything that would make it "illegal" but apologise in advance if it is. I need some assistance with design of a circuit for a project I am building for a charity fair, to help do some fundraising. It is probably a simple request but any ideas for "jazzing it up" a bit would also be welcomed. (Bearing in mind I have a fairly basic skill set and for example do not wish to do any soldering.)

    Anyway - here is what I am trying to do:

    I have a board, A1 size. The LHS of the board is split into a grid of 49 squares, within each square is an object. Underneath the object is either a pin, or a 2mm socket connector. On the RHS of the board is a list of names of objects. next to each name is either a pin or connector.

    The challenge to the game participants is to correctly link (i.e. connect) an object within the grid to the name for that object. I see this being acheived by use of a cable where each end has either a plug-connector or a croc-clip which allows the pin/socket in the grid to be connected to the pin/socket by the Name.

    Having made the link, a switch of some sort is activated, and if the link is correct, a (green?) light comes on. This is the very basic requirement. It would also be nice if I had a solution where when the link is not correct, something else happened! e.g. A red light comes on or even better a buzzer that makes that awful noise like the Family-Fortunes "WRONG" sound woud be great! (Want to make it fun!).

    Anyway - I presume it is something I could run off a few AA or C batteries. All suggestions gratefully received.

    Now the tricky bit - I only have five days to build it. And need to source my components within the UK (e.g. Maplins?). I am fine with connecting wire to terminals so think it will be quicker for me to take that approach than trying to learn to solder within that time.

    I think all of the info required is above but please let me know ifyou need anything further.

    Thanks in advance for any help offered.

  2. jcsd
  3. Jan 18, 2009 #2
    Sounds simple at first reading but not so simple to actually do.

    It could be done with pulses which have to arrive at the at the same time.. would mean a lot of logic circuits..integrated circuits ob printed circuit boards or vero boad.. a lot of fiddling about to get ot to work..

    Another idea. Instead of plug/sockets and wire jumpers.. Push buttons.. one by the object and one by the name. Wire them in series ( in twos..the correct two) and then the whole lot in parallel with an led and resistor (or buzzer) in series . So if you press the wrong combination of push buttons there is no circuit. Push right the combination then there is a circuit.

    Thinking about the wrong condition indicator now. Not so easy.
  4. Jan 18, 2009 #3

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  5. Jan 18, 2009 #4

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  6. Jan 18, 2009 #5
    Thanks Pumblechook for you suggestions. I was thinking this through about how to do it practically and came up with a circuit which is pretty much same as yours I think. I'm attaching it.

    I thought if a croc-clip was at the C end of BC it woud be manually attached to the pin next to the name of the object that has to be found. Then the person playing the game effectively is holding the connector AD and has to use the connector/croc-clip to touch the pin/socket at the crrect place in the object-grid, i.e. they make the connection at D. Then once both connections are in place switch S would be pressed on to see if the light lit up :-)

    Regards the transistor to detect a wrong answer, is this a fairly standard component? I presume to do this there would be another circuit such that when switch S is pressed, if there is *no* voltage between A and B then the buzzer sounds. Would there be a transistor that could have crimped cable connections or am I likely to be forced to do some soldering here ?

    Anyway thanks a lot for your help so far which has got me going in the right direction I think...

    Attached Files:

  7. Jan 18, 2009 #6
    I was wondering if anyone could help me out with something. I have a motion sensor component layout and i wanted to apply this to a recording camera of some sort. Or to a remote buzzer or lamp. SCHEMATIC.jpg Is there a way to get the layout of a recording camera to find out where i could implement it into this circuit?
  8. Jan 18, 2009 #7
    You could use mini choc block to terminate the transistor and resistors but really soldering would be better. Emitter to battery -ve. Base to the junction of all the resistors. May have play around with resistor values.. 22 kOhm or higher (too low and the LED will light (slightly) when you dont want it to.

    Low voltage Buzzer between transistor collector and battery -VE. You want an NPN transistor which will handle the buzzer current.

    LED only works one way round. 150 Ohm resistor in series with it.

    You may need to use 4.5 V supply or put a 2.2 K resistor across the LED or the transistor may not switch on.


    Buzzer or lamp could replace the relay in the motion sensor or just use the relay contacts to form a switch.
    Last edited: Jan 19, 2009
  9. Jan 21, 2009 #8
    Would it be easier to make it so when the sensor is tripped, that a camera starts recording?
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