Laser Challenge

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What a wanky idea! I'd much rather use a chest unit with the sensors mounted on the shoulders, front and back rather than a simple gun with inbuilt sensors.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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The units used at the local LasarQuest have sensors on chest, back, shoulders, outside gun housing, and down the barrel.

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Also, i've seen "joke" zap pens which give the user a mild electric shock when used. They run off three or so button cells, using some sort of DC-DC converter (high-voltage, extreamly-low-current). Is there any way to create a "souped-up" version to punish users for being shot? I don't particually want to give anyone heart attacks - or mabee I do.....

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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abcminiuser wrote:
Freaks,

Ok, now back to the topic. I've changed my system; there is now 3 micros involved. The master micro controls all the LEDs, gets signals from the gun and SensMicro and controls the LCD. The SensMicro listens continuously for electronic "bullets" and holds a "SHOT" pin high (to be read by the master micro), until the master aknoweges by pulling the "sACK" pin high - then both pins go low. This was made becaus the pulse delays were so short, the one micro coudn't have any delays for fear of missing a shot (or recieving corrupt data). The third micro is in the gun, and transmits via the Tx and Rx pins to the master via a 1m curly-cord 4-core cable.

I've read a little about IR Modulating, but how EXACTLY is this done? I saw a simple example of a 32kHz (I think) modulated IR beam for an alarm (break the beam and set ot off), but how does the reciever stay in sync? The design only used a standard IR reciever connected to a PIC, although presumably the PIC checked to see if the signal was 32kHz. Anyone going to shed light on this for me?

- Dean :twisted:

hey! can you please point me to that alarm reading? im trying to do a traffic counter. :D

hmm... im only 16... we should start a youth AVR group :P

Math is cool.
jevinskie.com

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Jevin,

The modulated alarm gizmit project was in the circuit notebook of the Australian "Silicon Chip" magazine, but I can't remeber the issue (some month 2004). Check your library, or the Silicon Chip Magazine website (search Google) as they may have it online. At the very least, the site will tell you the issue's month.

Hmm, 16 eh? Yeah, we should start a Youth-Group for "TINYfreaks"!

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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G'day Dean,

It looks like you are going full speed ahead with your project.

I feel that it is imprortant to state that infra red laser should never be used for this project because they can do damage to your eyes without you knowing for the simple reason that you can't see them.

My preference would be to use focussed red led's for the project and put as much work into getting them to work as possible. (The intensity of an LED is much lower than a laser due to a laser being able to be focussed to a very small point)

From reading some of the initial messages, I thought that you may want to look at a different formatting of your signals.

You may want to look at some data sheets for DTMF transmitter/receiver/transceiver chips to judge their practicality for your project. They are used in phones for the tones that you hear when dialling. They put two sound frequencies together to make each sound. At the receiver it checks for appropriate two sound frequencies and signals which of 16 patterns it has found. They can also require the two frequencies to be sustained for a desired period of time before accepting such a match.

You should be able to get away with one transmitter and receiver per person. (An op-amp should be able to add all the detector signals before feeding them into the receiver)

The only problem is that most readily accessible Aussie electronic shop don't seem to stock both if any at all.

Have a look for DTMF data sheets on the Web to get an idea of how they work.

I just had a look at Rockby and they have a few transciever for between $4 and $10.

http://www.rockby.com.au

Hope this is of interest :wink: ,

Mondon

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Thanks, very interesting. The project's actually on hold for now, as a company has asked me to write the documentation for their next board (not bad for a 16yo!). I'll let you guys know when I continue the project.

Also, I was going to use standard focused IR LEDs rather than lasers - the same ones that are used in remotes, so they'll do no damage.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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Hi Dean,

I am very new on this forum (and with avr's) but i have been working with lasers and electronics for quite some time now, so here'e my 0.02c :)

1 Anything over 1mW (laserpoint) can cause eye damage, the "official" limit for example for 5mW is about 5u Sec and for 10mW it is about 20uSec and This is not a "linear" thing for exposure vs time.

2 Infrared lasers are dangerous, as you cant "see" or "feel" what you do.

3 if visibility is a problem, use 635 nM lasers, better than 650, and 670.
because 650 and specially 670 are on the "edge" of the range of visible light. (a 1mW 635nM can well look brighter than a 10mW 670nM laser).

4 if you use 40Khz you could use laser-light but IR-technology!!!.

5 An IR (100nM) filter in front of a red laser (650nM) leaves you with.... nothing at all for your detector.

6 Modulation is the only way to "recognise" you lasersignal.

7 As soon as you are "outside" of the laserbeam the intensity drops
from 100% to 0 in typically 2mRad (about 0.2 degrees!!) so the "size" of
your sensor will decide if it's a hit or miss.

I hope this is of some use to you

Jean Michel

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Thanks, also very interesting. I was thinking, could it be possible to create a "true" 2 or 3 wire system (with power included?). I thought you could rig up the output of a 485 chip (which permenantly runs power by swapping + and - voltages on two wires to a MOSFET or somthing, to provide several amps of power along the data lines. At the other end (gun), you could use a bridge-rectifier to get out DC voltage regardless of the polarity and then use that to feed the circuitry.

It seems possible, but you woud have to provide the 485 voltags via a seperate power source (regulator?) to the MOSFET, as the 485 translateor chip would not provide sufficient current.

Possible?

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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hello abcminiuser,

Just a thought on your internet purchasing problems. You can phone order from Mouser. They are just about like any other large old mail order company. They'll even start sending you their catalogue after youve ordered once (you can probably just request one over the phone too). Of course their catalogue is hundreds of pages (think yellowpages phonebook).

Tyler

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Thanks, I might actually give Mouser a go - I LOVE electronics catlogues! What are their prices like?

We've got an olllddddd RS catalogue from '93 with thousands of items (with full chip specs and pinouts) that I drool over, you could beat whales to death with it it's so large.

Any feedback on my power over 485 idea?

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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Mouser's prices seem fairly competitive. They sell some things piecemeal, while others you must buy in quantity. I keep looking at something, getting excited over its price, then noticing that its only if you buy 2000... Just browse their site to get an idea. Same with DigiKey, although I have been less impressed by DigiKeys prices. Its probably just what Im looking for though.

Sorry, no idea on the 485.

Tyler

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I'd also need a bootloader instead of reprogramming the unit each time I upgrade the firmware. I plan to add an "initialisation" section to the code, you you can send mode commands through the serial port to set lives, ammo, etc.

I saw some short-range RF transmitters for AU$10 each in the back of the Silicon Chip magazine, perhaps this could be used to send scores back to the computer and recieve commands wirelessly?

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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