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Dirt Cheap Laser Tag

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LAN_403

Chip Fixes

Thu Apr 26 2012, 02:49AM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

So, a few days before I was going to go laser tagging, I was gazing at a TV remote and I realized that it wouldn't be too difficult to replicate a laser tag system by copying the action between a TV remote and a TV. so I did a little research and found out that the IR receiver basically acts like a relay and 'closes' the circuit when it picks up an infrared light wave at a frequency of 36,000hz.

Then I started thinking of something simple that could generate a 36khz frequency to drive and IR diode... 555 timer, cheap, easy to use, and mostly reliable. After this discovery I figured out that a laser tag system could be produced cheaply and easily. Since I'm a senior in high school I figured this would be a great idea for a "senior prank."

I talked to a lot of friends and everyone is in agreement that it would be awesome to have a giant laser tag battle between seniors near the end of school and that they would be fine with paying for the cost of parts/labor. I'm planning to sell at least 100 of them, however, I'm not sure whether to charge $5 or $10. It would be nice to make a little profit but I don't want to scam anyone, and I want to get as many seniors to buy them as possible.

A few hours on paint and I have a schematic:

Each person would have a laser "gun" -since it'll be used in school it will probably be a flat piece of cardboard (think key-chain flashlight). The gun components would be mounted on the cardboard and would be 'activated' by pushing a push-button. The IR LED would be mounted inside a .22 drilled out bullet casing (or small diameter copper tube) to better direct the waves.

The receiver would be mounted on a a piece of cardboard safety pinned to their shirt (cheap). I don't want to have to buy a bunch of different components so I am going to make it one big free for all by having all the guns send out the same frequency wave as all the receivers, including their own. I don't think activating their own receiver will be a problem as they would have to purposefully point their gun at their own receiver (I think?). Anyway, when the receiver was activated it would cause a pager motor to vibrate and 3(?) red LED's to turn on.

What I could use some help with:
I'm planning to use a TSOP2836 as the receiver because they're the only ones on Electronic Goldmine and I plan to order all my parts from there because I can rely on the shipping, unlike Ebay. However, they only have a range of 20 feet so I was wondering if I increased receivers or IR LED's, would it increase the range? (I think 50 feet would be much better). Furthermore, the receiver only allows, at the most, 6v and 5ma through which is not enough to drive the motor and led's, would there be a cheap way to step up voltage/current? Also, does it matter what duty cycle I use with the 555 timer?
I'm not set on using 9v for power, if 2 AA's would work better, so be it.

Thank you a ton in advance for any help/suggestions I receive!!!!

EDIT: The receiver will have an on/off switch

jnbrex

Thu Apr 26 2012, 03:02AM

Registered Member #3950 Joined: Wed Jun 15 2011, 12:45AM
Location:
Posts: 51

Definitely make a light and a sound when someone gets hit! Might not be a good idea to bring anything like that to school though... high schools are very strict about anything that sounds like a weapon (even though obviously what you are talking about isn't remotely dangerous, they might not understand that).

Chip Fixes

Thu Apr 26 2012, 03:05AM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

I've talked it over with the principle and gave him the details about my idea. He said it's fine as long as it doesn't resemble a gun.
I can make it light up, but idk about the sound..

Bjørn

Thu Apr 26 2012, 04:02AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

To increase the range from 20 ft to 50 ft you need (50/20)^2 = 6.25x the power. You can get that by increasing the number of LEDs or by driving one harder. Remote controls usually use short pulse lengths and high power to get high range and low power consuption. Some of those 5 mm IR LEDs can take short pulses of several ampere.

If you are going to make 100 it is a good idea to give it a lot of thought and testing before you start building, otherwise it will get very tiresome.

mister_rf

Thu Apr 26 2012, 08:16AM

Registered Member #4465 Joined: Wed Apr 18 2012, 08:37AM
Location: Bucharest, Romania
Posts: 145

The circuit of the TSOP2836 was designed in that way that unexpected output pulses due to noise or disturbance signals are avoided. For that we need to provide a data signal that fulfill the following condition:
â€¢ Burst length should be 6 cycles/burst or longer.
â€¢ After each burst a gap time of at least 10 cycles is necessary.
â€¢ The data format should not make a continuous signal transmission. There must be a signal gap time (longer than 15ms) at least each 90ms.
So we need to modify the transmitter circuit, itâ€™s not any more just a simple 555 circuit.

â€¢ By the other hand, in practice you need also to modify the receiver circuit in order to react at very short pulses and to change and memorize the status from 'ON' to 'OFF'â€¦

â€¢ Thereâ€™s also a problem related to local interferences from the receiver to transmitter, due to the wall and other obstacle reflections, and the ideal solution to use dedicated codes for each transmitter, and a list of codes accepted by the local receiver in order to reject local transmitter code.

I do not want to disappoint you an ruin your idea, but definitely, for the actual requirements: to be portable, low voltage operated, thatâ€™s a microcontroller job, not a simple classical hardware implementationâ€¦

Chip Fixes

Fri Apr 27 2012, 12:29AM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

Ah thanks! As for the gap problem... is there a different receiver that isn't picky? I don't want to go the micro-controller route

Dr. H.

Fri Apr 27 2012, 06:35AM

Registered Member #931 Joined: Mon Jul 30 2007, 05:25PM
Location: Bulgaria
Posts: 486

Good day Camp Badger

I definitely think you should use a MCU. It would be definitely more cheap than timers, logics etc. And making corrections to the algorithm is much easier. I have another question - have you thought about focusing the beam ? The IR emitters used in the remote controls are "not" focused.

Cheers

Carbon_Rod

Fri Apr 27 2012, 07:46AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

PIC12F508 $0.71
Vishay TSOP382 $0.98
IR TX led $0.26

It is easy to raw drive the modulated 38KHz unique ID TX codes in assembly...

Chip Fixes

Fri Apr 27 2012, 12:34PM

Registered Member #3781 Joined: Sat Mar 26 2011, 02:25AM
Location:
Posts: 701

Oh i've never used a PIC before so I guess I never realized their simplicity. Obviously I've never programmed them before either... is there a steep learning curve? I havn't bought any parts so it's not too late to make some changes.

EDIT: I planned on focusing the IR with a small piece of copper pipe or .22 bullet casing

Tetris

Fri Apr 27 2012, 03:43PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

Heh. Where do you get the recievers and such? I think this is a cool idea and I might want to build one for myself and my cousin. Also is the cardboard transmitter going to be open (so that the circuits show?) I think you should add a top layer of cardboard to minimize the risk of the thing snapping or something. I also think cling wrap to show the circuitry (because I've noticed people think a battery connected to a resistor and a LED think that it is extremely awesome), so showing off the (more complicated than the LED light) circuit would raise your social status.

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