# A Cheap Laser Tag

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## Introduction: A Cheap Laser Tag

Christmas Holiday is one of the most awaited holidays in the

year. We have loads of DIY projects on internet which you can make during Christmas holidays

So inspired by one such project of MAKE magazine I decided to build a simple circuit for a laser tag game

There are at present loads of projects on internet regarding laser tag but this circuit is unique and can be built in a few pennies .Though it doesn’t have a score maintaining and other features but it presents us an opportunity to built a cheap circuit which can serve the basic feature of a laser tag

## Step 1: Materials Needed

1) NPN Transistor (2N3904) x2

2) LDR x1

3) LED x1

4) 3v battery and holder x1

5) PCB x1

6) Potentiometer 50k or 10k x1

7) Wire

If you don’t have a potentiometer then you can use resistor from 1k to 10k but I prefer you to use a potentiometer

Tools

• Solder iron and wire
• Laser
• Wire Stripper

## Step 2: Understanding the Circuit

One of the most important things is to understand that how does this circuit work or else it would be just like copying and pasting some matter from website without using BRAINS to understantd how it works

So I am going to explain you the concept via a video and written matter

Written matter is separated in 2 parts

1. Understanding the circuit
2. Understanding the logic or brain due to which this circuit works

Now I will directly start with the explanation of the laser tag circuit and for all those who don't know you can check these sites

or

view the above video

So in the circuit we have a LDR ,a resistor and 2 Transistors

Now look at the circuit as I explain

• When Light Hits LDR At sufficient level
1. Current flows through the battery to the joint of LDR and LED
2. The current flowing through LDR gets little but reduce as More light means Less resistance for the LDR
3. But then also base lead of transistor receives less current than the amount flowing through the collector lead of transistor so the current flows through the junction of base and collector
4. Now at the junction of base and emitter current again flows as there is no current at the emitter
5. But then this will supply the current to the base of 2 transistor but again as compared to the current coming to the collector it is more than the current at the base of 2 transistor so current flows and the circuit subsequently get complete
• When light doesn't hit the LDR
1. Now in this case the LDR would give high resistance and its such that the base of the 1st transistor doesn't get the needed current and thus the connection wont be able to complete
2. Now due to incomplete current flowing through the 1st transistor it further makes the second transistor OFF or due to not getting any current at base transistor is unable to make the circuit complete
• Now you might be thinking that why do we have the other resistor so its basically to support theory that current always finds the path with low resistance in other words the current will floe through the part of the circuit that has the least resistance so now you know that why do we have this resistor as we cant change the value of LDR to get it work well in problematic situation like there may be high light in one room and low light in other room
• So by just decreasing or increasing resistance of the resistor you can get desirable result I hope that you are so far with we
• So this is how this circuit works so lets have recap
1. When light falls on LDR its Glows the LED
2. When there is darkness it makes the LED dim

## Step 3: UNDERSTANDING THE CIRCUIT ++

### Now get ready to know the main concept which made this project a success

SO as in the earlier part we studied that we light hits the LDR , LDR make the LED glow or in other words starts light so thus again that LED light which was started by some other light source glows and give light to the LDR and this process continues again and again making LED glow till some obstruction is there b/w the LED and LDR or the 2nd resistor values change(the resistor other than LDR) to such extend that the circuit circuit stops and thus the light of LED

Now enough of talking gather up you tools and parts and get ready to make one for yourself

## Step 4: Placment of the Parts # MOC

• First place all the components on PCB following the circuit which is given in the fritzing image

Or

You can etch your PCB board I have given the fritzing image

Here are some tips for how to place components efficiently
i) The 2 transistor can be placed such that the collector of 1st transistor and collector of 2nd transistor are at adjacent holes of PCB and the emitter of 1st transistor should be adjacent to base of 2nd transistor

ii) Now try to place other components similar to the images given

iii) Remember not to cut the extra leads of resistor and LED it will be useful for you at time of soldering

iv) Remember to place LDR and LED facing opposite to each other this is what that will make this circuit work

• Now cut the PCB but remember to leave some place if you would require it at time of soldering

#MOC is Making of circuit :-P

## Step 5: Soldering #MOC

Now you have to solder the parts remember not to get your components damaged

Here are some useful tips

1. Keep the iron tip clean. A clean iron tip means better heat conduction and a better joint. Use a wet sponge to clean the tip between joints. Keep the tip well tinned.

2. Solder small parts first. Solder resistors, jumper leads, diodes and any other small parts before you solder larger parts like capacitors and transistors. This makes assembly much easier.

3. Use adequate ventilation. Most soldering fluxes should not be breathed in. Avoid breathing the smoke created and make sure that the area you are working in has adequate airflow to prevent buildup of noxious fumes.

4. Before use, a new soldering tip, or one that is very dirty, must be tinned. "Tinning" is the process of coating a soldering tip with a thin coat of solder. This aids in heat transfer between the tip and the component you are soldering, and also gives the solder a base from which to flow from.

YOU WOULD GET A SIMILAR PRODUCT AFTER SOLDERING IT

## Step 6: Testing Time #MOC

Now first test it by putting 3v battery in holder

Now adjust the value of potentiometer such that the LED gets just off .

Now point the laser to it LDR and see the result>>>>>>>>>>LED should get on.

Take help from my video this also shows how to turn off the LED using 2 techniques

Congo on creating your first Laser Tag At a low cost don’t forget to post the pictures of it will surely help others to make it.

## Step 7: Finishing Up #MOC

Now all you have to do is to make it attach to the cloth Images will help you through this step i found that the little space which i left was helpful for me at this step

## Step 8: PLAY TIME !!!!!

Kudos !!!!!!!! You did a great job now all you have to do is enjoy the result of your hard work make some more of them and play with your friend .

Take a look at the fight of me and my friend actually its just me shooting but i had a great time with it and check out the critic comments too

## Step 9: Future Plans

You can further modify it using a 555 timer circuit in

different modes for the laser

Astable mode

This would help you to make Laser a machine gun style just click the button and the laser pointer will on and off I have made this circuit like that way So here are some images of it and the circuit to guide you

Monostable mode

This would be help full when you want to give the person just one chance to shoot the target usually I used it for making a shot gun in which you have just a fixed no of chances in India we usually during fairs or MELA for that you would be need to make a 555 timer circuit in Monostable mode

In the circuit just connect the laser pointer to the output and the ground make sure that you connect it with the same polarity.

So if you have any question regarding the circuit or explanatory part just post the comment Enjoyyy and forget to like my Youtube videos.

Participated in the
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Participated in the
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## 24 Discussions

How do you get hit? What senses the hit?

LDR senses the hit. For a better info try to go through the project once again.Though if you are asking how LDR works?Answer is that it changes its resistance when the light hits it,hence the name Light Dependent Resistor(LDR)

hi sir i want to develop this with a lager led lights and and wth a bigger baterry and ldr which is trigered by laser in daylight i am an ncc cadet pleasse help me as it can benift many cadets if this works

Its a difficult prospect to use it in bright light.as it depends on light to trigger the system.You can try out other methods to achieve the result for weapon training.But if you still wanna try this idea out in day light you could try to make laser pulse in a particular frequency and then use a decoder at the target end to detect if the same frequency of light is being hit on the ldr,for that to happen you would need some basic knowldege of logic gates and timer chips like 555 timer

Thank you for answering... final question, could I just use a light to activate the LDR? I thought it would be tough to hit the LDR at a long distance with a laser

But with led you will not be able to concentrate a beam so, this will make the game senseless as even if you just point it left or right to the person ldr will still detect it. If you are looking for gameplay where you can shoot a person from long distance best idea would be to use laser as they long range and to make target big use a bigger ldr and make reflector from aluminum foil just like we have in our flash light this will ensure if you even hit a person 20 -30cm far still that will be taken as a hit

Yah like the one used in camera flash. But this will only be able to give you short range. For long range laser is the only buddy

Potentiometer gives you a way to calibrate your laser tag according to environment light cause after all the ldr will sense all lights whereas you want it to trigger the led only when laser strikes it so a potentiometer is nice to have you can swap that with the resistor if you are gonna play inside and the light amount is constant through out the day

Yes any kind will work

I hope that IgorS20JackANDJude and vforturan are able to make it by yourself if you have any other quires please ask and if you have made it then please share your tags pic here

can i use any other transistor

I have the

Bc 2222

Bc 547

Bc 548

Bc 557

And

Bc 558

?

#### I have mentioned 2N3904 only because it works great with LED But still you can use other transistor but only NPN

Yahh sure you can do so but first check its datasheet or try it with one LED with the type of circuit and see that is it working

I really like this happy,happy!

ThanksJackANDJude

Try to make it and send us those amazing images