Hi all. Recently started building a lightsaber using all the usefull info and tools everyone kindly shared but after some testing and couple burned hp-leds i've got couple questions:1. In the schematics you use 100k resistors but i didn't find any notes if it's supposed to be 0.5w, 1w, 2w or any other?2. I tried single 18650 battery with dc-dc step up connecting it to 5v pin on arduino but it doesnt seem to work, well it powers up but instead of normal sounds the df player starts to produce some crackling sounds. So i switched to 2x16340 to get 7.4-8.2v. As for mosfets i tried 2 different types
In terms of mosfets, it's important to select those which can carry a min of 2A, low Rdson and logic level (meaning a Vgs threshold not greater than 2.5V). If the Vgs is close to your battery, the fets are not fully in which could explain the dimness. And if your red LED will switch on earlier than the blue and greed due to a lower threshold, it could "steal" the current from the other 2 if your battery cannot supply enough current for all 3.
No stupid question, only stupid people who do not dare to ask. If a transistor has 2-4V Vgsth, you need a 5V supply. I would anyway urge you to use either a DC/DC to boost your 3.7V to 5V or power the board over the VIN with >6V. But then there should not be any crackling. Did you have any Wav files on the SD card you use? If yes, in the right format?