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Limiting Resistor for LED Drivers

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ikefor

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Hi all,

I'm a newbie and not really and EE person but need some assistance
I am trying to build a power supply that will deliver about 348V using 2 LED drivers connected in series. I also have a digital voltmeter connected to the circuit which displays the voltage and current that the unit delivers.

Since my digital voltmeter maxes out at 300V, i don't want the power supply voltage to exceed 300V rather i want it to output around the 295Volts sweet spot.

I know that i can use a limiting resistor to limit the output voltage but need some help to calculate the exact resistor to use to achieve this.

Any assistance will be appreciated.
 


348V CAN KILL YOU so stay away from it until you learn something about it.

Resistors limit current, not voltage. If you limit the current then the circuit using the current might not work. If you limit the current with a resistor then the output voltage also MIGHT be limited depending on the load (no voltage limiting with no load). You can make a voltage divider with two resistors in series with 348V at one end and 0V at the other end but the resistors will get hot and the output voltage from between the resistors varies when the load current changes.

An LED uses a low voltage. Why do your LED drivers produce such a high voltage?
 

if you want to limit the led voltage youll have to remove some of the leds so there's less of them in series.
Alternatively you could try reducing the current and seeing how much that reduces the led voltages, but youll need the led datasheet for that.
 

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