Laser Tag & circuit ideas

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Dippy

Moderator
I didn't realise that it had such a following amongst project-builders.
Very interesting.

The optics all look a bit naive though.
 
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CaptainTuna

Member
Those where the sites from which i started from, i know them since 2003 or so, but thanks anyways ;)

The fact is that i don't like those system. I want to make a system which is more realistic, closer to "military-simulation". I'll tell you what how i want my laser tag project to be:

- magazine changing made "physical" (you don't just have to press a button to do that like it is on the first site you showed)

- directional hits; the player knows from which angle he was shot, he doesn't have to guess....

- grenades; i am gonna use those toilet roll tubes and stick about 4/5 IR LEDs, and a 08M, should be very easy

- more sensors, also on the chest

and nothing else comes into mind at the moment, feel free to give me some tips!
I also don't want to make it "arcade" as some may think when the word "laser tag" comes into mind. As i (think) have said before i played airsoft and that's in no way an arcadish game, is much more realistic.
One thing: also the US army has its own laser tag system, so this may give you an idea of how it is.
This is just a photo, that my clarify the idea of how i want laser tag to be, once again is not a dark maze with funky lights :)
 
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Dippy

Moderator
You guys like to dress up really butch then? :)

In principle:
1. Magazine changing - easy.
2. Grenades - easy. Use something a little stronger. You want them to last don't you?
3. More sensors - easy.

4. Direction - phew!

Serious questions:
1. How big is your budget?
2. How much development time do you have?

Seriously, to make something tough you are going to have to spend a few bob.
Sure, use bog rolls and stuff for prototyping, but that won't last 5 minutes in the Real World when your 20 stone friend accidentally stands on the grenade.

I suggest you have a play with IR LEDs and sensors in daylight to get to grips with what is required.

You could make a really 'Pro' system, but its gonna cost in cash and time.

But, good luck, it sounds great fun. I'd love to have a go at it myself.
 
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CaptainTuna

Member
My aim is to make it cost not too much. Something like 200$ maybe. (not too much compared to airsoft...)

My budget is not too big actually, i don't work, i am still in high school. But i believe that's not gonna limit me. If i make some nice prototypes maybe may former airsoft team will accept them and would want to buy some (at least that's what they told me some time ago) so that could make the whole thing easier.
As for now my aim is to make prototypes, i'll have to start with something on breadboard. I've done the sound module already, so now i have to concentrate on the reception/shooting of IR beams.

As for development time, well I will have holidays in a month and a half or so, so again that's no big problem.

Summary: first i make prototypes, then i will try to see if my airsoft team wants to have a go with it :) Once i get the system working correctly i will post schematics and other things so anyone can use it and/or imrpove it.

One last thing about Direction (4): that is what i was trying to achieve by dividing the sensors in 3 different areas so that you can understand where the shooter is by knowing which sensor receives the IR beam.
(i know this is VERY approximative but i see no other way to make it more precise)
 
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Rickharris

Senior Member
Make the shooting gun make a suitable noise - In real life that's about as much as you know (believe me I know) and if you get hit you loose all interest in where the shot came from (no personal experience but I know people who have), your colleagues may be interested but the sound gives them the clues.

You may see muzzle flashes or not with modern weapons.

To be realistic you need a range of weapons from pistols to heavy machine guns with appropriate fire power and range and rate of fire.
 
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CaptainTuna

Member
maybe you're right, i should care more about sounds and less about IR directioning. My initial plans were to use IR directioning because sounds were not that powerful on the sound modules i made.

As for the muzzle flash other system use bright LEDs so i think i should stick with that.

The system can be applied to pistols / heavy maching guns / snipers at user's discretion. Maybe it would be right to set a limit (eg: max 2 snipers) but that depends on the rules set by the players.

Summary: i'll try to see if i can somehow make the sound louder. I am already using a 200 gain-sound amplifier but it doesn't help much.
 
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Rickharris

Senior Member
200x then there is something wrong - Even my modest 25 watt hifi blows your head off if turned up loud.

Of course it depends 200x what?
 
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Rickharris

Senior Member
I have found the 386 to be a bit picky when trying to get loud sounds out (mainly music and i was bothered about distortion) Suggest for a gun sound a simple transistor amplified would do just as well - lots of circuits out there.

Even a pizeo sounder - driven correctly they are ear shatteringly loud (see car alarms)
 
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Dippy

Moderator
Depends on piezo and how loud.

I read, but have never tried, that an open collector with an inductor across Piezo terminals can be pretty good. Inductor in mH range. Time to have a play.
 
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papaof2

Senior Member
CaptainTuna said:
i used this one http://www.futurlec.com/Linear/LM386N-1.shtml
actually i am not sure, maybe it was 20 not 200 (voltage gain).
Click to expand...
The voltage gain isn't that important. The LM386 only provides 250mW (1/4 watt) of audio, which isn't that loud outside, even with a horn type speaker Try moving up to the LM380 (2 watts audio output) http://www.allelectronics.com/make-a-store/item/LM380/2-WATT-AUDIO-AMP/-/1.html. Depending on the ambient noise and the distance to be covered, you could be looking for 10 watts or more (there are some single chip solutions), but more volume means more battery drain. For comparison, electronic sirens on emergency vehicles are in the 100 to 200 watt range http://www.emergencyresponderproducts.com/mosiss.html.

John
 
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CaptainTuna

Member
Thank you very much for the insight papaof2. I think I'll try ordering a few (shouldn't cost much) to play with them and see which one does the best.
As for the resistance of the speaker, how is that involved in the overall output sound? I guess having a higher-ohm speaker does more but since i am not an expert with these i have no idea of which one i should be getting (most projects i have seen use 8-ohms though)
 
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Andrew Cowan

Senior Member
Half, the resistance, double the current, double the output!

As long as you have the means to drive it (current wise), so go with the lowest speaker you can find.

A
 
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CaptainTuna

Member
Alright, thanks for the info.
I now need a PWM generator, i can't use the pwmout command on picaxes tuned at high frequencies. Do you suggest to do this with a 555 timer, or is there some better way?

EDIT: but i don't think i'll really need 64MHz, 32 should be fine enough, and pwm works at 32MHz. (if i am not wrong 32MHz means 8000 instructions per second)
 
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Dippy

Moderator
I hope BB isn't watching!

For producing nice loud sounds you should pay more attention to the speaker 'sensitivity'.
You should also concentrate on what sound you want it to make.
I assume you want to make a BANG sound and not a 'Peep' or play Beyonce's Greatest Hits in full Hi-Fi.

Whether you choose piezo or a coily speaker you must look at how you enclose it too.
This will make a huge difference.

I'd start with the optical sensitivity aspect first before sound ... project creep and all that :)
 
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Andrew Cowan

Senior Member
I'll agree with Dippy about speaker mounting. If you ever take apart a <battery powered> radio or something with a speaker in, try the speaker when it is fully assembled, then remove the speaker and try it again. Once the well designed resonant speaker housing has gone, it is much quieter.

Same with cased piezos - put a piezo against a big sheet of plastic or in a well designed case, and it will become much louder. A deeper and richer sound, too.

A
 
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Dippy

Moderator
And there's the issue.

Most off-the-shelf low cost cheapo piezos are mounted in a plastic case to give a healthy 2kHz to 5kHz resonance. Maybe overloading a with a pulse stream will do it, dunno.
Perhaps a horn style piezo or tweeter speaker would be better as they prodcue a wider range and might give better bang sounds, mind you they are quite big.

I reckon for loud sounds then size may be an issue unless you can find something special - time to part with cash and have a play. And you'll need quite loud for outdoor use.

... after the optics though.. so back to the plot ;)
All the best - nice project.
 
hippy

hippy

Ex-Staff (retired)
A PICAXE using HPWM can drive piezos at considerable volume, and particularly around their resonant frequencies.

http://www.picaxeforum.co.uk/showthread.php?t=11548

Again, that's pure tone though.

Having got my hands on a Poundland car charger using the 34063 DC-DC converter, I'm wondering about using that in step-up mode ( can generate +40V in theory ), connect the piezo to +40V and driving the piezo via a FET/Transistor as a relay would be. That would give around a 0V/40V swing which should be very loud.

On the choice between piezo and speaker, don't forget that the lower the speaker coil, the more current is used, the quicker the batteries will drain.

For a 'proper sound effect' something more than a pure tone is needed. It may be possible to find an 'effect generator chip' which gives a sound as needed and it should be possible to use that with a piezo to a high voltage rail for volume.

If you can determine the wave of the sound effect it could be possible to dedicate a fast, large memory PICAXE to bit banging / PWM'ing / HPWM'ing out the required signal for a piezo.
 
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Dippy

Moderator
Those chips tend to be low voltage and low power so will need gain if the noises are to be heard by sweaty pseudo-paras at a distance and outdoors.
So, will need work and experimntation.
 
hippy

hippy

Ex-Staff (retired)
Andrew Cowan said:
Hippy - would you pull the piezo low in that setup, or just go from 40V to floating?
Click to expand...
You'd drive it High/Low if using a FET/Transistor.

It may be possible to direct drive a piezo to +largeV ( Low and Input/Floating ) but that depends on the current ( 25mA max sunk into an I/O pin ). I have no idea of the resistance of a piezo when operating. Also piezos generate electricity when you tap them so no idea what happens when the I/O goes floating and the piezo springs back to being flat, you might need back-EMF catch diodes, zener clamps.
 
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CaptainTuna

Member
sounds complicated, thus i like it! :)
I think i'll google piezo/speaker to understand their difference so i'll know a bit more about them. I was talking about speakers just because the schematic on the ISD showed one, not because i thought it was better or anything like that!

Since i understand i will be able to (somehow...) get loud enough sounds i might forget about the totally unprecise idea of calculating the direction of the beam by using different sensor areas.
This means that i will be using only 1 interrupt and that makes things much easier, i actually already tried the single-interrupt transmission and works well.

EDIT: doesn't the driving of piezo sounders with PWM just give you a pure sound instead of, say, a "bang" (even if i alter the frequency/timing/etc..). I mean: are "bit-banged-with-pwm" sounds better than ones that come out of an ISD?
 
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Dippy

Moderator
At PICAXE speed I can't imagine anything too impressive.
I'd just send a darned great click and let the piezo/box do the resonance.

I might try that // inductor method I mentioned earlier just out of interest. That might resonate nicely. But your average cheapo piezo element dangling in mid air will be pretty rubbish.
 
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Andrew Cowan

Senior Member
I have a PICAXEd clock. It sends a 0.5ms pulse to a cased piezo, and this makes a 'tick' just like a real clock does.

Not a bang, though...

A
 
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CaptainTuna

Member
So i think i'll stick with the ISD....i don't know if i have the space for a resonance box, considering it has to end up inside the rifle.
 
hippy

hippy

Ex-Staff (retired)
Dippy said:
At PICAXE speed I can't imagine anything too impressive.
Click to expand...
I'm not sure. Windows 3.xx used to have a sound driver which controlled the PC's mother board speaker / piezo with PWM and that wasn't too bad from memory.

A PICAXE can have a long sequence of HIGH/LOW or PWMDUTY commands so it's just like POV blatting out what you need. CALIBFREQ would give some dynamic speed control. On some PICAXE's there's a Voltage Reference which can be routed out to a pin ( need to poke SFR's ) and that can give a 16-step DAC which worked reasonably well when I tested it.

I've been planning on getting a PICAXE to talk if it can for a while but haven't had the time to experiment.
 
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CaptainTuna

Member
Hi guys it's me again!
I checked my airsoft rifle and convinced myself there is no way i'm gonna put the LED in the barrel, i need some sort of tube as mentioned before. I took some of the photos that should prove this.

First one shows the barrel of the gun and its diameter:


This one show an airsoft silencer (IR+lens could be inserted here):


here are other two photos (could include 4 pictures at most):
http://img15.imageshack.us/img15/9638/dscf3324y.jpg
http://img43.imageshack.us/img43/310/dscf3326.jpg

There are also some other things i wanted to show you. First is the magazine housing. If this was a laser tag converted replica i would have to put inside it two electrical contacts, something like the ones you find on the bases of cordless telephones or battery holders, but i really do not now where to buy them (making one myself wouldn't be a problem but it becomes pain when i have to build 10 or more...so i'd prefer something standardized)
Here it is:


Last thing, i also checked out an airsoft pistol and i've noticed there's not much space inside. As for now i'll take care of bigger stuff, then if it works properly i'll try to mess up with those, but again, it'll be a secondary thing.
I took this photo to emphasize the little space inside pistols (or at least, the little space inside pistols that operate with gas)
 
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CaptainTuna

Member
i think it would but the problem is the lens. I could put the lens just outside of the barrel though. WHY have i never thought of that? :D BB pellets have diameters of 6mm. You know what? When i'll convert it to a laser tag replica i'll just take away the inner barrel (the one in which BB pellets go) and just keep the outer one, that makes positioning of the led quite easier, but still hard to handle.
Hopefully the very narrow beam that comes out of it won't be a problem for the sensors.
 
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Dippy

Moderator
Does everyone/anyone else get all that annoying junk when looking at an image on imageshack?
Tinypic is better.

With the picture of the silencer haven't you answered your own question? Flat top LED plus lens. My old lens supplier did 20mm lenses in various FLs - not cheap though.

Or consider the VCSEL I/R laser LEDs from Optek.
Available lensed or flat I believe.

I really don't think any (average) 5mm LED would give enough oomph to give the range outdoors.

Magazine:
Does it have to be electrical? Could it be optical?
 
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CaptainTuna

Member
Sorry about imageshack, i'll use Tinypic next time.

About the silencer: yes it would definetly be easier mounting everything on the silencer, but the bad thing is that you are forced to use it. I'll explain myself: in real life you choose whether to use the silencer or not as it may give you advantages and disadvantage, whereas if i have the lens+led in it every player will be forced to use it.

As for the 5mm LED, other guys have used the in silencer setup and they say that, at night, driven at 1A it reaches distances of 200 meters.

As for VCSEL, i'll document myself on the laser class "1M"...as always safety first! Don't want to do anything wrong.

The magazine can be optical: i'll have to document myself on that too :) Thanks for all the options you listed! They are really helpful.
 
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CaptainTuna

Member
Ok, this might be a totally crappy option but i don't know why it came into mind:
What if you put the sensor in the barrel and the LEDs on the body? This might be crappy because:
-it consumes much more (IR lights have to be on all the time)
-range might be shorter (non lensed LEDs on the body)
 
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SilentScreamer

Senior Member
I think CaptainTuna means the sensor is mounted in the barrel and when the trigger is pulled the IR sensor is read. Each player is covered in IR LEDs making them "beacons".

EDIT: The exact reverse of the original/conventional idea.
 
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Ruzzz

Member
There is one minor point, not related to electronics, you might not have thought about, the Violent Crime Reduction Act (VCRA).

You are talking about manufacturing a Realistic Imitation Firearm ( RIF ). Unless you have one of the specific defences mentioned in the act, you are on very shaky ground, and on even shakier ground trying to sell it.

There is a sub forum on Arnies airsoft devoted to this, it might be worth posting on there what you are doing.
 
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