Micro webcams.
August 25, 2006 5:27 PM Subscribe
I am looking for some really small webcams. Micro webcams or something similar.
What would you recommend? I am interested in something that is as small as a package as you can possibly get. I want to put them inside of things that are burning and be able to film the flame propagation as well as possible.
They will be completely disposable video cameras, and don't necessarily need to be webcams but I thought a webcam would be the cheapest solution for this project.
Maybe pen size video cameras?
I dunno. Thanks for your input!
What would you recommend? I am interested in something that is as small as a package as you can possibly get. I want to put them inside of things that are burning and be able to film the flame propagation as well as possible.
They will be completely disposable video cameras, and don't necessarily need to be webcams but I thought a webcam would be the cheapest solution for this project.
Maybe pen size video cameras?
I dunno. Thanks for your input!
Possibly of use: A lot of webcams become a lot smaller once you take the case off - in many cases, much of the interior of the case is empty space.
posted by -harlequin- at 6:27 PM on August 25, 2006
posted by -harlequin- at 6:27 PM on August 25, 2006
Out of curiosity, are you planning on using wireless ones, or just yanking the cord once it starts to burn? Have you thought about using an extension cord to keep the computer away from the flame and possibly give you more time to yank it out? You've probably thought of this last, but just in case: water on an electronic cable is a very bad idea, especially if it's being burned through. Make sure you've figured out how you're going to put out the flame in case things go wrong, so you can save the computer.
posted by spaceman_spiff at 6:49 PM on August 25, 2006
posted by spaceman_spiff at 6:49 PM on August 25, 2006
You don't even need the water. Once it's being burned through it can short out from the insulation not being there any more, even without water.
posted by mendel at 7:40 PM on August 25, 2006
posted by mendel at 7:40 PM on August 25, 2006
Response by poster: No worries guys. I am making a living burning things here, and I just need a good look inside of a chassis to observe an electrical fire. I really don't care if the camera dies in the process, as long as I can get good video from it while it is alive then it is worth the $19 or whatever.
Good suggestion removing the case off of a web cam. I'll buy a cheap one and see what that is like. The more bulk the more it could potentially affect the test.
nlindstrom: thanks for the tip.
posted by nickerbocker at 7:44 PM on August 25, 2006
Good suggestion removing the case off of a web cam. I'll buy a cheap one and see what that is like. The more bulk the more it could potentially affect the test.
nlindstrom: thanks for the tip.
posted by nickerbocker at 7:44 PM on August 25, 2006
Some tint NTSC cameras (like the ones posted above) plus a video digitizer / DVR type card seems like the cheapest solution, especially if you want multiple cameras (you can get multi-input cards) and expect to lose many cameras to the flames.
It should be possible to make sure that shorts caused by the fire won't damage the other equipment (shorts from the power supply to the video cable seem the most likely to be troublesome, assuming the supply itself can survive a short).
posted by hattifattener at 7:47 PM on August 25, 2006 [1 favorite]
It should be possible to make sure that shorts caused by the fire won't damage the other equipment (shorts from the power supply to the video cable seem the most likely to be troublesome, assuming the supply itself can survive a short).
posted by hattifattener at 7:47 PM on August 25, 2006 [1 favorite]
Response by poster: spaceman_spiff: no...wireless would likely see a lot of interference from the initial arcing. And it would be more expensive.
You've probably thought of this last, but just in case: water on an electronic cable is a very bad idea, especially if it's being burned through.
The fire will not be put out. It will be setup in a flame resilient chamber with a hood. It will burn until it goes out or all the fuel is consumed.
posted by nickerbocker at 7:47 PM on August 25, 2006
You've probably thought of this last, but just in case: water on an electronic cable is a very bad idea, especially if it's being burned through.
The fire will not be put out. It will be setup in a flame resilient chamber with a hood. It will burn until it goes out or all the fuel is consumed.
posted by nickerbocker at 7:47 PM on August 25, 2006
Response by poster: good advice about watching for shorts, hattifattener!
Any ideas on how the USB controller on a laptop might react to its pins being shorted?
Good call on a NTSC video digitizer. The link anadem posted would be perfect. I can run 9V from a constant/limited current power supply, so shorts will not be a problem.
posted by nickerbocker at 7:53 PM on August 25, 2006
Any ideas on how the USB controller on a laptop might react to its pins being shorted?
Good call on a NTSC video digitizer. The link anadem posted would be perfect. I can run 9V from a constant/limited current power supply, so shorts will not be a problem.
posted by nickerbocker at 7:53 PM on August 25, 2006
Solving the short problem may be tricky. For starters, I'd add some sort of external USB hub (i.e. don't connect them straight to the motherboard). Perhaps optoisolation is the ticket.
I Am Not An Electrical Engineer
(yet!)
posted by phrontist at 8:05 PM on August 25, 2006
I Am Not An Electrical Engineer
(yet!)
posted by phrontist at 8:05 PM on August 25, 2006
Nickerbocker: I was thinking more along the lines of damage (by fire or a short) to the computer hooked up to the camera, and wondering how you were planning to prevent that. But it looks like phrontist's ideas are
posted by spaceman_spiff at 8:37 PM on August 25, 2006
posted by spaceman_spiff at 8:37 PM on August 25, 2006
The only safety issue is the spreading fire. I mean, it is a fire, you know, and they spread, and that is a big deal!
Electronically though.. The 5v or 9v power supply to the camera shorted to a pin of the I/O connector might be able to damage something, but I think it is pretty unlikely.. You'd have to research the specs of the I/O port your going to use (video-in, USB, or whatever), but a short to 9v doesn't seem that serious. Serious enough that you should run a few tests - try intentionally causing the short circuits that might happen, a partial short is probably even more stressful, but you don't want to spend days testing :P Even if nothing is damaged by a short, you may see shutdowns caused by short circuit protection - bad for your data..
posted by Chuckles at 9:05 PM on August 25, 2006
Electronically though.. The 5v or 9v power supply to the camera shorted to a pin of the I/O connector might be able to damage something, but I think it is pretty unlikely.. You'd have to research the specs of the I/O port your going to use (video-in, USB, or whatever), but a short to 9v doesn't seem that serious. Serious enough that you should run a few tests - try intentionally causing the short circuits that might happen, a partial short is probably even more stressful, but you don't want to spend days testing :P Even if nothing is damaged by a short, you may see shutdowns caused by short circuit protection - bad for your data..
posted by Chuckles at 9:05 PM on August 25, 2006
Regarding how a laptop USB hub/port would respond - a short in a homemade USB device destroyed mine.
If I were you, I'd use an el-cheapo PCMCIA USB adapter, and on top of that, a powered USB hub. Get the short as many stages from your motherboard and integrated USB controller as possible.
posted by fake at 9:10 PM on August 25, 2006
If I were you, I'd use an el-cheapo PCMCIA USB adapter, and on top of that, a powered USB hub. Get the short as many stages from your motherboard and integrated USB controller as possible.
posted by fake at 9:10 PM on August 25, 2006
The problem with putting a USB hub.. There isn't likely to be any electrical isolation between the camera, the hub, and the computer (there might be, but not for $5.00), so you aren't really getting anywhere. Much better to use a disposable PC (like any old PIII) than hope that a USB hub or PCMCIA card will isolate the problem.
posted by Chuckles at 9:26 PM on August 25, 2006
posted by Chuckles at 9:26 PM on August 25, 2006
You might also consider isolating each camera from each other, not just from the data acquisition device (whatever it might be). If they all share a simple common power supply, a short in one camera might cause loss of data from all cameras as opposed to just the camera with the fault.
posted by RichardP at 9:46 PM on August 25, 2006
posted by RichardP at 9:46 PM on August 25, 2006
Do you have to use a computer? An NTSC camera and a cheap VCR might be more sensible.
posted by cillit bang at 5:43 AM on August 26, 2006
posted by cillit bang at 5:43 AM on August 26, 2006
Response by poster: Electronically though.. The 5v or 9v power supply to the camera shorted to a pin of the I/O connector might be able to damage something,
Nope. The level of magnitude of energy is really on completely different scales with the event. You can take two leads from a current limited power supply and short them with your hands all day and it isn't going to hurt your equipment (or you). In fact you HAVE to do that in order to set your current limit! Once the limit is set to a couple of mA above what is required by the camera it is operating the worse things a short does is draw more power. At 9V, you are not going to see very much arcing either.
Solving the short problem may be tricky. For starters, I'd add some sort of external USB hub (i.e. don't connect them straight to the motherboard). Perhaps optoisolation is the ticket.
You are right, phrontist. Optical isolation would protect your equipment, but there could be other problems with that route, mainly with speed. I could print out an intermediary board with some sockets and 2 USB connectors.
NTSC signals are still probably the best solution for reasons of cost and protection of equipment. The composite cables going into the computer pose no risk if they are shorted with themselves because they are such low power.
posted by nickerbocker at 8:24 AM on August 26, 2006
Nope. The level of magnitude of energy is really on completely different scales with the event. You can take two leads from a current limited power supply and short them with your hands all day and it isn't going to hurt your equipment (or you). In fact you HAVE to do that in order to set your current limit! Once the limit is set to a couple of mA above what is required by the camera it is operating the worse things a short does is draw more power. At 9V, you are not going to see very much arcing either.
Solving the short problem may be tricky. For starters, I'd add some sort of external USB hub (i.e. don't connect them straight to the motherboard). Perhaps optoisolation is the ticket.
You are right, phrontist. Optical isolation would protect your equipment, but there could be other problems with that route, mainly with speed. I could print out an intermediary board with some sockets and 2 USB connectors.
NTSC signals are still probably the best solution for reasons of cost and protection of equipment. The composite cables going into the computer pose no risk if they are shorted with themselves because they are such low power.
posted by nickerbocker at 8:24 AM on August 26, 2006
Nickerbocker: Shorting one of the USB lines to +9 does seem like it could easily damage the USB port. Just because there's no macroscopic, visible arcing doesn't mean it won't blow out a chip. The USB spec does require that shorting to +5 or ground must not damage the port (USB 2.0, §7.1.1), though.
Optoisolating a USB connection is difficult because the data lines are bidirectional — they get turned around under protocol control.
As for NTSC cameras, it sounds like you're in a lab setting, so maybe you could just use a bench supply that'll survive short circuits, and install DC blocking capacitors in the video lines to protect the computer input (on the off chance it doesn't already have them ... it probably does).
posted by hattifattener at 11:26 AM on August 26, 2006
Optoisolating a USB connection is difficult because the data lines are bidirectional — they get turned around under protocol control.
As for NTSC cameras, it sounds like you're in a lab setting, so maybe you could just use a bench supply that'll survive short circuits, and install DC blocking capacitors in the video lines to protect the computer input (on the off chance it doesn't already have them ... it probably does).
posted by hattifattener at 11:26 AM on August 26, 2006
Response by poster: I have bench supplies that will survive up to a 30 amp short circuit :). I know, I've had to pump 30 amps into a short before. The cameras will be less then an amp, and my power supplies will be limited to that. They will be more then fine.
posted by nickerbocker at 10:05 AM on August 27, 2006
posted by nickerbocker at 10:05 AM on August 27, 2006
It isn 't the power supply I'm thinking about, it is the USB port or the composite video in, or whatever. Any I/O port will have a maximum voltage rating (maximum current too, but one hopes the port already protects against that possibility). I think damage is unlikely, but tests are easy, and disposable hardware is plentiful, so..
A current limited power supply set appropriately will help limit the risk of damage even more.
posted by Chuckles at 12:48 PM on August 27, 2006
A current limited power supply set appropriately will help limit the risk of damage even more.
posted by Chuckles at 12:48 PM on August 27, 2006
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posted by anadem at 6:12 PM on August 25, 2006 [1 favorite]