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Jonnie Wilson

Array Driver

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I am trying to source locally (Australia) a constant current LED driver. firemanjim gave me a link to one in the US but the shipping cost to get them posted here is way too much.

The LED array will have 24 clear white .5w leds. From the information pasted below can anyone tell me if this one would be suitable?

Thank you. John

 

http://au.rs-online.com/web/p/constant-vol...rivers/6671661/

 

Recom RCD-24-0.50/W Constant Current LED Driver 2 → 35V 0.5A 17.5W

RS Stock No.667-1664Manufacturer Recom Mfr. Part No.RCD-24-0.50/WRecom

Recom RCD-24-0.50/W Constant Current LED Driver 2 → 35V 0.5A 17.5W

 

Product Details

Constant Current LED Driver, RCD-24 Series - Wired

Non-isolated

Drives up to ten 2W power LEDs

Constant current source

Output current accuracy ±2%, Output current stability ±1%

Efficiency up to 96%

Wide input voltage range

Short circuit protection

Compact package

Connection Data

Wire Function

1 (Red) +Vin

4 (Black) GND

5 (Brown) -Vout

6 (Yellow) +Vout

Note

Operating temperature is without derating.

MTBF to MIL-HDBK-217F (25°C).

Edited by Jonnie Wilson

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to know for sure we need more information on the LED and battery you are using. The driver needs to be paired per the configuration of the LED and battery voltage you are using. The 10 2W leds the driver reports is probably 10 2w leds in series with 35 volts applied to it. The board you are using is using has 8 parallels of 3 in series. With that driver you would have 87.5ma across each LED which is likely less than it is rated at.

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to know for sure we need more information on the LED and battery you are using. The driver needs to be paired per the configuration of the LED and battery voltage you are using. The 10 2W leds the driver reports is probably 10 2w leds in series with 35 volts applied to it. The board you are using is using has 8 parallels of 3 in series. With that driver you would have 87.5ma across each LED which is likely less than it is rated at.

 

Boy this is confusing.

Below is a link to the LEDs I will be using and I will either be using a small sealed acid 12 volt battery or if it would work, sets,of 3 18650 lithium batteries that would be around 11 volts. The array board was given to me to make up and yes it does have 3 rows of 8 leds in parallel. Unfortunately I don't really understand all the technical side of this.

http://m.ebay.com/itm/221299391249?cmd=VIDESC&gxo=true

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The DC forward current on those LEDs are 100ma. That is the proper current to run those LEDs at with the current board setup and with this driver you would only be powering each leg to 87.5ma. To figure this out you take the total current of the driver which is 700ma (.7a) by the total parallel circuits which is 8 in this case and that comes to 87.5. So if you only use 21 LEDs in 7 parallel circuits you would be come out to 100ma which would be perfect for this LED. The driver will work but it will be much dimmer unless you take out a parallel circuit of 3 leds. You could over power them with a different driver like a 1a (1000ma) driver with all 24 LEDs and it would be 125ma (1000/8) The would be over bright this way.

 

The only problem with this is that the LEDs may burn out if they overheat. Nights are usually cooler which helps in this situation because we really are talking about physical heat that damages the LED. Running current through anything produces heat and these LEDs dissipate 500mW of heat. So if you are worried about overheating because you are over powering the LEDs the best thing is to put a longer delay in between the recordings. Go to a feeder mode and likely the LEDs would be ok. If you know you don't get a lot of triggers at a time then even this may not be necessary for the cooling.

 

The second part of picking a driver is the voltage. These LEDS have a DC forward voltage of 3.2 to 3.4 volts. You have 3 in series for each parallel leg. So you would need 9.6 and 10.2 volts to be able to run them correctly. Usually you should add a volt loss for the current regulator. so that would take us to 10.6 to 11.2 volts needed to run the regulator and LEDs together. With a SLA battery you are going to be fine since its voltage is usually 12 to 13 volts with a load on them. With 3 18650 the voltage is around 11v with a load on them and that is going to be usable for a short period of time and then when the voltage falls down low it really will not be able to regulate the current properly thru the circuit. 4 18650 would give you around 14 volts (LED driver can take 35v) which would drive the LEDs great and it would take a long time for the voltage to drop below the 11.2 volts of the upper end. Most of the mosfets that drive the LED arrays that the boards can use can usually take these higher voltage without issue. The current again is the downfall since even a mosfet can only dissipate so much heat.

 

Hopefully this helps you and gives you a little background in how to pick a proper driver to go with your LEDs.

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Thank you for your help and patience.

So a driver with a output current of 1000mA should cover the LED array?

I've found plenty on eBay with the specs listed below, hopefully these would be ok. Can get the same input output voltage range that have an output of 1500mA but that would be too much?

 

Item: Ldd-1000H

InPut voltage: DC9-56V

Output Voltage: DC2-52V

Output Current: 1000mA

Tolerance: +/-5%

Efficiency: 97%

package include:

1pcs meanwell ldd-1000h led driver 1000mA

 

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It should be ok with the 1000ma driver. Just test it a bunch to make sure the LEDs do not burn up with the amount of time you will have the array on. Just start with the shortest video length and move up to the length you want. You can feel the LEDs and if they seem warm to the touch then maybe shorten the length. If they are warm, see how quickly they cool off.

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