Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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Basically I have a couple of lasertag guns, they have 3 what I believe are IR sensors on them to detect the hits, what Im trying to do is extend the sensors away from the gun.
the sensors themselves are black 2 pin IR receivers (I think)
Anyway I removed the sensors off the pcb no problem, then I attached a 12inch wire to each point where it was joined with the sensor then attached on the ends of these wires.
Tested it out and it received hits on the sensor perfectly, however the gun wouldn't fire properly, it was sometimes not firing at all, then sometimes it was taking a few seconds for it to fire after pulling the trigger. This is where it gets strange to me...
Removed the sensor and left the wires the same length but with no sensor or anything on the ends, same problem. However if I cut one of the wires down to about an inch, or remove it altogether the gun works fine!?!? What is this voodoo? why would it matter how long the wire is especially as there is nothing even on the other ends of the wires?
The only thing I can think is perhaps the wires are acting as some sort of aerial, or causing some sort of RF interference? in which case would using shielded wire help?
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ed
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Registered: 10th Sep 03
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quote:
Originally posted by Steve
What is this voodoo?
Physics, I believe,
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DaveyLC
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Registered: 8th Oct 08
Location: Berkshire
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You did wire up the IR LED's around EXACTLY the same way you removed them yes? 
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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Yeah, but they aren't really part of the equation as the problem happens even with no detectors on the ends of the wire.
Basically 2 12 inch wires attached to the pcb with nothing on the ends, the gun wont fire properly.
If I just cut one of them down to about an inch it works fine
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DaveyLC
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Registered: 8th Oct 08
Location: Berkshire
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The wire you are using might have quite a high natural resistance.. or maybe your soldering sucks? Have you tried testing the impedance with a meter?
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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Nope, the resistance thing has been mentioned to me today aswell, so will try some thicker wire later.
This was a guys reply on the electronic forum who seemed to think it could be related to the wires acting like antennas
quote:
Yes and Yes. The IR Rx circuitry will probably have a high gain amplifier of some kind which could pickup external noise. I don't know why the gun doesn't fire, maybe it does but it's just too fast for you to see and then it detects what it thinks is the return beam straight away. Or if it's receiving anything it just might not fire, that might be part of how it works.
Adam
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Cavey
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Registered: 11th Nov 02
Location: Derby
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IR beams show up on phone cameras don't they? That would show if its firing at all I guess?
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DaveyLC
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Registered: 8th Oct 08
Location: Berkshire
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BTW Steve, are you using shielded wire? If not, you should
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Steve
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Registered: 30th Mar 02
Location: Worcestershire Drives: Defender
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no and plan too 
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Bart
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Registered: 19th Aug 02
Location: Midsomer Norton, Bristol Avon
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Resistance shouldn't be an issue on such a short cable, assuming you've not wired it in something much smaller than the original cable. Volt drops normally only occur on really long cable runs.
Also, I can't see how a shielded cable would make any difference unless a data/analogue signal is being transmitted?
Again on such short distance and such a low voltage device I wouldn't expect it to pickup any interference.
quote:
Originally posted by Cavey
IR beams show up on phone cameras don't they? That would show if its firing at all I guess?
Tried this on a Siemens ultrasonic hand held programmer, it showed up on an old smartphone but not on my iPhone 5s..... odd
[Edited on 20-10-2014 by Bart]
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DaveyLC
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quote:
Originally posted by Bart
Also, I can't see how a shielded cable would make any difference unless a data/analogue signal is being transmitted?
That's what IR LED's are for.. serial data
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ed
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Registered: 10th Sep 03
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quote:
Originally posted by Cavey
IR beams show up on phone cameras don't they? That would show if its firing at all I guess?
They also travel at the speed of light 
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Balling
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Registered: 7th Apr 04
Location: Denmark
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quote:
Originally posted by Cavey
IR beams show up on phone cameras don't they? That would show if its firing at all I guess?
They used to. Some newer phones have IR filters.
I discovered this after trying 4 different sets of batteries in a remote only to realise my new phone didn't show the IR light. 
Ed, you look at the diode. The duration of the light output is typically slower than the speed of light. 
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Cavey
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Registered: 11th Nov 02
Location: Derby
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quote:
Originally posted by ed
quote:
Originally posted by Cavey
IR beams show up on phone cameras don't they? That would show if its firing at all I guess?
They also travel at the speed of light
You know I didn't mean taking a photo of it 
And I didn't know they'd filtered them nowadays, still show up on my Nexus
[Edited on 21-10-2014 by Cavey]
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