Leds With Resistors (parallel) Reducing Source Voltage
Posted 12 December 2012 - 10:25 AM
You are working with LEDs that have a 10.6 Ohm resistance.
Wonderful proofing calculator.
You have a 56 ohm resister in series with each LED, bringing a single chain to 66.6Ohm resistance.
Using the Value over Number Formula, running 12 LED sets in parallel brings you to 5.5 Ohms total resistance.
Now, I make absolutely no claims on being a genius, so I will throw out my guess and let it go from there, but it seems to me, that 5.5 ohms is quite low. Low enough even, that the power supply may be sensing a short. Try reducing your parallel LED count to between 2 and 4 units. If the unit works correctly here, then I fully recommend using a "dumb" power source. IE a battery.
Posted 12 December 2012 - 04:10 PM
Posted 20 December 2012 - 06:43 PM
I have a 12V power adapter (from an old phone, 200mA) lying around, so I figure I'll try that. If each LED uses 3.5V, 25mA, 3 of them in series with a 56ohm resistor should be about right. (and then I have fewer parallel circuits)
Posted 01 January 2013 - 08:33 PM