Hey everyone! I'm a bit of a newbie when it comes to electronics, so I'm looking for some advice on resistors for my LED project. I'm soldering some LEDs in parallel, powered by a 3V source (like from a USB). Here are my questions:
1. I'm using 3.0 - 3.2V LEDs (mostly green, blue, and white) without any resistors. Is that okay?
2. For my 2.0 - 2.2V LEDs (red and yellow), what kind of resistors do I need? I'd love to understand the math behind choosing the right resistance as well! Thanks for your help!
2 Answers
Hey! It's generally not a good idea to run LEDs without resistors unless you have a current-limited power supply. Most supplies aren’t designed specifically for LEDs. Without a resistor, the LED can burn out if the voltage is too high.
For your 2.0 - 2.2V LEDs, I suggest using an LED resistor calculator online if you don't want to do the math manually. But basically, using Ohm's Law, you'll need to ensure the current stays below about 20mA, which is the typical max for most standard LEDs.
Remember, for LEDs in parallel, it’s best to use one resistor per LED to avoid uneven brightness. Good luck!
I’ve had some rough experiences testing LEDs directly with a battery without current-limiting resistors. Trust me, always use resistors! LEDs need a specific forward voltage to light up without burning out. Most standard indicator LEDs max out at around 20mA.
For your setup, use one resistor for each LED, and if you're going to wire them in pairs, you should still consider separate resistors for each LED in the pair. That way, you can ensure consistent brightness across the colors. Let me know if you need help with calculations!
Thanks for the heads-up! Just to clarify, resistors are sold based only on their ohm rating, right?