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Amperage, Voltage, and resistors.


Guest Anonymous

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Guest Anonymous

When it comes to batteries, the two main factors you will be looking at are voltage and amperage.

 

Essentially voltage is a measure of the intensity of current provided by the battery. Voltage is typically expressed as (V). The amount needed to power an LED to optimal potential is usually called forward voltage.

 

Amperage is essentially a measure of the amount of current provided by the battery. Amperage is typically expressed as A(amp) or mA(milliamp) 1000ma = 1A. Battery capacity is usually expressed in mAh, or milliamps per hour.

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Guest Anonymous

A resistor is a device that limits the amount of current flowing through a circuit for a particular applied voltage. That is to say... only so much current will flow with a certain amount of voltage and resistance. If the voltage stays the same, and the resistance goes up, then the current decreases.

 

This is good for saber builders since batteries rarely come in sizes that match the needs of LED's exactly. If you want to have enough juice to power those suckers to their brightest, you must use more voltage than the LED's can handle on their own. Adding a resistor lets you adjust the current flowing to the LED and avoid seeing smoke coming out the end of your saber.

 

The basic unit of resistance is the ohm. 1 Ohm of resistance is defined as ... the resistance of a circuit in which a 1-amp current flows when 1 volt is applied.

 

The generic formula for determining which resistor you need is:

(battery voltage - forward voltage)/amperage = resistor value

 

Example: If you have 3AA, each 1.5V and 2000mAh, wired in series, you will have a battery pack providing 4.5V and 2000mAh(2A). You are wanting to power a 3W LED with a forward voltage of 3.9V.

 

Using the formula above:

4.5 - 3.9 /2 = 0.3 Round up to the next whole number = 1. You would want a 1ohm(2watt) resistor. Always round up instead of down to make sure you are covered.

 

Note: If using 2 LED's (making a staff) and want to run both off of a common battery pack, wire the LED's in series(see diagram) add the forward voltages and treat them as one unit when determining resistor value. Install the resistor between the switch and first LED.

 

Using these principles, here is a link to a resistor chart that covers most of the basic LED's used right now. http://www.thecustomsabershop.com/forum ... php?t=1624

 

I am not a wiring expert. These are just things that I have learned along the way. If anyone has conflicting info: PM me. I will research it and make changes if needed.

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