1. ## LED Circuit Help

I am trying to convert a DeWalt (model DW919) work light to LED. I have the circuit assembled (sub-par diagram pictured here: https://imgur.com/a/PXR6dtH) but when I flip the switch the resistor fries. Did I get a way too small resistor? A little insight on what I did wrong in this circuit would be very helpful.

Circuit info:
20V DC source
1000mA driver (has dimmer, not using)
One Switch
3 Cree XP-G2 LEDs in series (one 3up star, Forward voltage @ 1000 mA =3.0v)
12.4 Ohm resistor

Thanks all

2. ## Re: LED Circuit Help

Welcome to the forums. Sound like it'll be an impressive light.

The resistor should not be part of the circuit. I am assuming you meant LDD-1000HW not LDD-100HW.

There are 5 wires on the driver. The white wire is PWM and can be ignored. The black wire is "V in -" and that goes to the negative of the 20V battery. The red wire is "V in +" and that goes to the switch. The other side of the switch connects to battery positive. The blue wire is "V out -" and that goes to the minus side of the LED array. The yellow wire is "V out +" and that goes to the positive side of the LED array.

3. ## Re: LED Circuit Help

Originally Posted by parametrek
Welcome to the forums. Sound like it'll be an impressive light.

The resistor should not be part of the circuit. I am assuming you meant LDD-1000HW not LDD-100HW.

There are 5 wires on the driver. The white wire is PWM and can be ignored. The black wire is "V in -" and that goes to the negative of the 20V battery. The red wire is "V in +" and that goes to the switch. The other side of the switch connects to battery positive. The blue wire is "V out -" and that goes to the minus side of the LED array. The yellow wire is "V out +" and that goes to the positive side of the LED array.
I just tried the circuit without the resistors, and the LEDs didn't turn on, and the driver started smoking (I have more drivers, nbd).

When I include the resistors (before they start cooking), the lights activate but they cycle (blink) every second. I have limited circuit expertise so this is a head scratcher for me.

The battery model is a DCB203 if that helps. Thanks in advance if anyone has a solution.

4. ## Re: LED Circuit Help

Originally Posted by harmfulcow
I am trying to convert a DeWalt (model DW919) work light to LED. I have the circuit assembled (sub-par diagram pictured here: https://imgur.com/a/PXR6dtH) but when I flip the switch the resistor fries. Did I get a way too small resistor? A little insight on what I did wrong in this circuit would be very helpful.

Circuit info:
20V DC source
1000mA driver (has dimmer, not using)
One Switch
3 Cree XP-G2 LEDs in series (one 3up star, Forward voltage @ 1000 mA =3.0v)
12.4 Ohm resistor

Thanks all
As noted, no resistor, but you are hooking it up wrong. Note the standard application circuit in the data sheet.

Vin+ to + on battery.
Vin- to - on battery.

Vout+ to LED+
Vout- to LED-

DO NOT connect Vout- to Vin- ... as stated not to do in the data sheet.

Odds are you shorted out the current sensing resistors that are inside the DC-DC convertor, hence the smoke. That one is a throw-away. When you had the resistor, you were still somewhat shorting them out, but the current would only go up to 1A. Other things were happening that caused the flash.

5. ## Re: LED Circuit Help

Originally Posted by ssanasisredna
As noted, no resistor, but you are hooking it up wrong. Note the standard application circuit in the data sheet.

Vin+ to + on battery.
Vin- to - on battery.

Vout+ to LED+
Vout- to LED-

DO NOT connect Vout- to Vin- ... as stated not to do in the data sheet.

Odds are you shorted out the current sensing resistors that are inside the DC-DC convertor, hence the smoke. That one is a throw-away. When you had the resistor, you were still somewhat shorting them out, but the current would only go up to 1A. Other things were happening that caused the flash.
V out - is connected to the - LED terminal, V in - is connected to the - battery terminal, V out + is connected to the + LED terminal, V in + is connected to the + battery terminal. I can see where my rather crappy circuit diagram might not have made all that clear. Here is a picture of the wiring without power to the circuit, red and black wires being + and - respectively. There isn't a switch in this one, I just pull the power connection since it is a test setup.

https://imgur.com/b6jzNdD

Thanks for all the responses all

6. ## Re: LED Circuit Help

Originally Posted by harmfulcow
V out - is connected to the - LED terminal, V in - is connected to the - battery terminal, V out + is connected to the + LED terminal, V in + is connected to the + battery terminal. I can see where my rather crappy circuit diagram might not have made all that clear. Here is a picture of the wiring without power to the circuit, red and black wires being + and - respectively. There isn't a switch in this one, I just pull the power connection since it is a test setup.

https://imgur.com/b6jzNdD

Thanks for all the responses all

I figured it out. The problem the whole time was the 20v Dewalt pack had its own power regulating components inside. When I hooked the circuit up to a "dumb" 18v dewalt, it worked just fine. Thanks again for the help guys/gals

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