ezrafitch1990

01-29-2011, 07:11 PM

my friend wants me to build a sign for them with lights so they can bring it to a bball game, i figure 8 LED's around the perimeter of the sign wuld work.

thinkin of using these:

http://www.radioshack.com/product/index.jsp?productId=3111495

these lights need 20mA of current and between 3.2-3.8 volts.

i drew it up in multi-sim and hooked the lights up all in parallel, and set the lights to 20mA and 3.2V. the multisim lights have an unchangeable resistance of 160ohms, and i was thinking of powering the circuit with a 9V battery. I did the calculations and figured I would need a 48.333 ohm resistor but used the 48.7ohm:

http://i52.tinypic.com/2hp51ms.png

My questions:

What size resistor would I need? (wattage)

How would I ground the circuit if my friend is going to be holding the sign up?

How long would the 9V battery last? Should I connect another battery?

of course ill change the resistor size but i dont know the actual resistance of the LED im gonna buy ill measure that lata

thinkin of using these:

http://www.radioshack.com/product/index.jsp?productId=3111495

these lights need 20mA of current and between 3.2-3.8 volts.

i drew it up in multi-sim and hooked the lights up all in parallel, and set the lights to 20mA and 3.2V. the multisim lights have an unchangeable resistance of 160ohms, and i was thinking of powering the circuit with a 9V battery. I did the calculations and figured I would need a 48.333 ohm resistor but used the 48.7ohm:

http://i52.tinypic.com/2hp51ms.png

My questions:

What size resistor would I need? (wattage)

How would I ground the circuit if my friend is going to be holding the sign up?

How long would the 9V battery last? Should I connect another battery?

of course ill change the resistor size but i dont know the actual resistance of the LED im gonna buy ill measure that lata