DS-2cd2432F-IW LED Votage?

B

Brenning

n3wb
May 17, 2015
27
1
Hi All,

The IR LED in my DS-2cd2432F-IW appears to have failed and I'm looking to replace it with a 940nm one. However, when checking the voltage across the two terminals with my multi meter its showing as 5v? Most IR LEDs I can see only run at 1.5-1.6V. Did Hikvision use a special LED or am I reading something incorrectly?
 
LEDs are spec'd to run at a current level. The most common circuit is something like a 5 or 12 volt supply driving the LED in series with a resistor. With the LED removed, a meter will read the supply voltage. When the LED is in the circuit, it will pull the voltage down to the ~1.5 volt junction voltage. The combination of the supply voltage, series resistance, and junction voltage determine the current. Your camera might have a more complex power supply for the LED. My point is that all that matters is the completed circuit current, not the open circuit voltage. If I took on this project, I'd add my own additional series resistor to the circuit with the new led, starting at 1k ohm, and measure the current. Then I'd slowly lower the added resistance until the desired current is achieved. The desired current is whatever does not exceed the rating of the LED or the power source. I'd bet my nickel that in the end the answer is to just add the new LED and all will be well, but there's always a risk when you don't know the specs for the original part.
 
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