ir beamer

Post by **Edwin** » Sun Nov 23, 2008 11:15 am

Hi i have a linksys camera without nightview,
i`m thinking about to add a ir beamer(about 60 euro)http://www1.conrad.nl/scripts/wgate/zco ... width=1024

but don`t
know of its a good combination.
anyone have experience with it?

Post by **TANE** » Sun Nov 23, 2008 11:37 am

Edwin,
you can also try the ir leds they cost about 1 euro.
some of th camera's has build in ir filter, ir will then not help

ps links from conrad will not work this way

Post by **MindBender** » Sun Nov 23, 2008 12:47 pm

Hi Edwin,
Unless you use a black&white cameara without or with removed IR cut-off filter, IR LEDs will do you not much good improving your camera's night vision.

Post by **Edwin** » Sun Nov 23, 2008 1:45 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chak
 Edwin,
you can also try the ir leds they cost about 1 euro.
some of th camera's has build in ir filter, ir will then not help

ps links from conrad will not work this way

Post by **TANE** » Sun Nov 23, 2008 10:23 pm

Not sure if it will work..this are the products that you can tray.
Some time ago I was going to convert modify my Axis camera after reading the next article.

http://www.jasonmacpherson.com/adding-n ... y-monitor/

LED's:
IR-LED-LAMP 5 MM LI520C
Bestelnummer 175321 - 89

IR-LED-LAMP 5 MM LI521
Bestelnummer 175322 - 89

Potmeter:
PT 15 LH 250 R
Bestelnummer 431184 - 89

Post by **MindBender** » Mon Nov 24, 2008 6:43 pm

Again: If your camera is not suitable for IR, you will not get better night vision using IR illumination.

You can test your cameras IR sensitivity using a remote control: In the dark, point your camera to an object about 1 meter away from the lens and try to illuminate the object with a remote control, keeping the remote control itself outside direct view of the camera. If you can see the object in the flickering 'light' of the remote, your camara is suitable for IR. If you don't, buying IR LEDs is pointless, unless you are planning to buy hundreds of them. Please note: Any camara can 'see' IR when pointing a remote directly into the lens, this means absolutely nothing.

Most black & white cameras can be easily modified to be more sensitive to IR: Usually there's an IR cut-off filter behind the lens, just before the CCD (or CMOS) sensor. It looks like a piece of light blue glass and it's usually not hard to remove it.

Color cameras mostly have their RGB pixel filters printed directly onto the CCD (or CMOS) sensor. These filters usually include an IR cut-off filter as well to insure correct colors at day time under presence of IR. More expensive night vision capable cameras (such as the American Dynamics SpeedDome VII Day & Night @ ~1800 Euro) have a separate IR cut-off filter, which can be retracted mechanically under low light conditions.
On cheap versions, the printed IR cut-off filter is purposely left out and a more rigorous white balance is used to deal with IR reaching the sensor during day time. At night time they switch to black & white and use a long integration time (== slow shutter).

TIP: Instead of LEDs, you can also consider using dimmed halogen lamps to produce IR. A 500 Watt construction lamp, dimmed to the level the filament barely glows, already radiates A LOT of IR. Three 20 Watt halogen spots put in series to spare a dimmer works well too. But remember that halogen lamps need to burn at 100% every one in a while, or their life span will suffer.

Post by **MindBender** » Mon Nov 24, 2008 8:13 pm

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Chak
 Not sure if it will work..this are the products that you can tray.<hr height="1" noshade id="quote"></blockquote id="quote">
It's not that easy: When you're using a potentiometer only, you can easily blow up your LED, burn your potentiometer or blow your fuse when the potentiometer is set at a low resistance.
But it's not that hard either: Besides the potentiometer, you can put an extra resistor in series to limit the current.

LEDs are diodes (hence the 'D'), which are non-linear components. Because of this you cannot simply apply some voltage to them. Instead they need a certain current. When buying an LED, the current they need is usually specified as Iforward, If for short. When this current is run through it, some voltage can be measure over it as a result. This Uforward, Uf for short, can be found somewhere in its datasheet as well.

Now to allow the LEDs to setup itself at its rated current, we need put a resistor in series with it. The value of that resistor can easily calculated for any voltage you need. First you subtract the LED's Uf from the power supply's voltage to calculate the voltage needed to be taken care of by the resistor. Once we know this voltage, we can easily calculate the value of the resistor because the current through it is already known: It's in series with the LED, so the current is equal: If.

For example: If we want to power an LED with an If of 20mA and a Uf of 1.8v using a 5v power supply, the series resistor needs to take care of 5-1.8=3.2v. Given Ohm's law (I=U/R), the minimum required resistance is 3.2v/0.02A=160Ohm. Rounded up to the nearest E12 value gives you a resistor of 180Ohm.

Again, please not that an LED cannot be powered without using a series resistor, not even if your power supply outputs the LED's Uf. As stated, it's a non linear component which needs this resistor to setup it's current.

Post by **Edwin** » Mon Nov 24, 2008 9:07 pm

Thanks for the ideas,
I will first try the remote with my camera.

greetings edwin

Post by **TANE** » Tue Nov 25, 2008 12:23 am

I'm not that deep in electronic to know that...friend of mine was going to build that.