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Hi, I asked my electronics teacher for some help but he isn't bothered so that is why I need help from you guys.

I am constructing a loop wire game in which you have to move a loop through a wire and once the loop touches, it warns you etc by buzzing and/or the use of LED/s. Here are the two schematics that I would like to combine. Also I have attached an attachment if the link isn't working.



http://tinypic.com/r/wv225g/6

The problem in the FIRST SCHEMATIC is that the buzzer will not sound for a predetermined time. The buzzer will only sound as soon as the loop touches the wire and won't sound after the loop doesn't touch the wire. The problem in the SECOND SCHEMATIC is that it doesn't involve LED/s to stay lit and a reset button like the FIRST SCHEMATIC.

I would like the combined schematic to function like this: When the loop touches the wire (acting as a switch shown in the schematic), the buzzer will sound for a predetermined time varying on the capacitor value and the LED will stay lit, and when the push to make switch(reset) is pressed, the LED will turn off.  

If someone can give me some guidance on how I should approach this problem, or if someone can provide me with the Solved Schematic of the above two schematics, then I'll be really grateful.  

Later on, I will use Arduino Uno to add countdown timer. Any suggestions would be appreciated.

Thanks A Lot


* 2 Schematics.JPG (72.23 KB, 800x480 - viewed 45 times.)
« Last Edit: December 30, 2012, 05:23:06 pm by 06awaism » Logged

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You do not combine sechematics. What you do is to design a circuit that does what you want.
Is there any point in doing this as if you use an Arduino you define how it operates in software and so there is no schematic to design.
By the way what is D2 in the first circuit? A diode only has two inputs not three, and if it is an SCR then it is drawn wrong.
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It is a thyristor. Similar to thermistor but has a slightly different operation. And what I mean by combining two schematics is to design a circuit (as you said) to contain both features as these two schematics have. And that is what I am having trouble with. I cannot design a circuit that has these two schematics on. Thanks.
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Apart from what Mike has already said, if we draw the circuit for you then you learn nothing.  May I suggest you have an attempt at drawing the circuit that meets your needs, then post it and we'll tell you if it's Ok or not; and if it's wrong we'll tell you why.  That way you will learn something.  As a clue, the two attached circuits have all the functional parts you need  -  all you have to do is work out which.
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Swap R4 and SW5 in the second schematic, and remove BZ3 in the first schematic. Then combine them, such that SW2 and SW5 become the same thing, as do SW3 and SW4. But as Mike says, if you will be using an Arduino anyway, then it's much simpler to just connect the switches, buzzer and LED to the Arduino, and do the buzzer and LED control in software.
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"Thermistor" ?  I think not.  A transistor is maybe what you meant.  Either way, they are quite different devices - but both classed as semiconductors.
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I am really sorry. I meant a transistor.
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Quote
It is a thyristor.
That is the same as an SCR.
Quote
Similar to thermistor but has a slightly different operation
No it is not remotely similar to a thermistor. And you do not draw it like that. The gate line is a diagonal line leading to the under side of the cathode.
http://en.wikipedia.org/wiki/File:SCR_symbol.svg

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the buzzer will sound for a predetermined time varying on the capacitor value and the LED will stay lit
You need two circuits, one that will commutate (turn off) the SCR after a pre determined interval. You can do this by having the SCR charge up a capacitor feeding into a unijunction that is wired across the SCR. When it fires the SCR is shorted out and so stops conducting. The other circuit is what you have already. The two are triggered from the same point.

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Swap R4 and SW5 in the second schematic, and remove BZ3 in the first schematic. Then combine them, such that SW2 and SW5 become the same thing, as do SW3 and SW4. But as Mike says, if you will be using an Arduino anyway, then it's much simpler to just connect the switches, buzzer and LED to the Arduino, and do the buzzer and LED control in software.

Thanks a lot for your reply. Well, I thought it would be complicated if I used countdown timer along with this circuit. So I thought I will make 2 circuits. One with arduino which will do the countdown timer and second which is the loop wire circuit itself.
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Similar to thermistor but has a slightly different operation
Quote
No it is not remotely similar to a thermistor. And you do not draw it like that. The gate line is a diagonal line leading to the under side of the cathode.
http://en.wikipedia.org/wiki/File:SCR_symbol.svg


Sorry, I was meant write a transistor.
« Last Edit: December 30, 2012, 05:53:48 pm by 06awaism » Logged

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I was meant write a transistor.
If you did then the circuit would not work like you describe it. Once you remove the gate voltage you turn it off and I thought you said it latches on. If you have an SCR it would latch but a transistor would not.
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I was meant write a transistor.
If you did then the circuit would not work like you describe it. Once you remove the gate voltage you turn it off and I thought you said it latches on. If you have an SCR it would latch but a transistor would not.

Sorry, everybody is getting confused. I have fitted a thyristor in the first schematic. But when someone asked me what this component was, I told them it is a thyristor similar to thermistor, which is wrong. Thermistor is a completely different thing. I was meant to write transistor as it is similar in someways to the thyristor.  
« Last Edit: December 30, 2012, 06:02:51 pm by 06awaism » Logged

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Well, I thought it would be complicated if I used countdown timer along with this circuit. So I thought I will make 2 circuits. One with arduino which will do the countdown timer and second which is the loop wire circuit itself.

Seriously, it's very simple to do with the Arduino. I suggest you start by connecting just the wire loop, LED + series resistor, reset switch and piezo buzzer to the Arduino. Writing a program that drives the LED and buzzer as you want will be easy. After that, add the display and the program for the countdown timer, which is a little more complicated.
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I'm with dc42. Do it all in software and minimize the circuit to a couple of wires and resistors, plus buzzer and LED for which there are heaps of examples.
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I was meant to write transistor as it is similar in someways to the thyristor. 
Again a transistor and thyristor (or SCR) are in no way similar.
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