In a message dated 6/7/03 11:40:57 PM Eastern Daylight Time, [EMAIL PROTECTED] writes:
<< The question is: what kind of resistor do I need to solder in between the 12V deep cycle battery and this LED to get to the right voltage? >> Ben: Most LEDs want a current of about 20ma (.020 A) and an operating voltage of about 2.0V. It doesn't seem to matter how big or bright they are (I have wired up big bright jumbos as night lights on a park flyer and much smaller ones in battery chargers, etc and they're all about the same in this regard). The spec sheet you cited shows likewise. So, if you want to drive them with a 12v battery, you have to drop 10v in the resistor at 20ma. Following Ohms law, voltatage = current x resistance, you need a 500ohm resistor to drop 10v (500 x .020 = 10). The closest standard value resistor is 470 ohm, spend the extra pennies and get 10% tolerance variety to avoid getting too far on the low side (standard tolerance is+ -20%). The resistor will have to dissipate .020 x .020 x 500 = 0.2 watts (watts heat = current x resistance squared), so a 1/4 watt rating resistor will be physically big enuf. One used to be able to get suitable diodes and resistors at Radio Shack, but these days I'm not so sure. Hopefully you have a walk-in electronics supplier in your area, we still have a few down here near DC. Good Lift! RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] Please note that subscribe and unsubscribe messages must be sent in text only format with MIME turned off.
