Hello guys, I'm trying to assembly and code my own lightsaber using Arduino. I am good at programming but have only basic electronic knowledge and need some help. My plan is to use a Cree RGBW led module to illuminate the blade, the problem is, I can only get the red led to shine at accepatble brightness. The other 3 leds light up but pale in comparison.
This is the circuit I’m using for testing (only RGB are shown, but connections for the white LED are exactly the same)
For each color I’m using a a TIP122 transistor, connected to the Arduino, through the base, using a 4.7 KOhm resistor. As a result, when the relative pin on the Arduino is high, I measure (without the led module) 3 V and 1 A between the collector and the positive of the batteries which will power the led. Which is pretty much what I desired and ideal I guess? The result however is that (connecting the led module) the red led shines brightly, the others don’t.
Voltages for leds, from the specification are: red 2.25~2.6 V, green 3.3~3.9 V, blue 3.1~3.7 V, white 3.1~3.7 V. Maximum Drive Current: 1 A. So maybe the voltage is too low for the other colors to shine as brightly? But the fact is that I tried also using 4.5 V instead of 3 to power the leds, and they are still dimmer than the red at 3 V. While connecting them directly to the power supply (3 V) they all shine super brightly instead.
Measuring the voltage and the current while the led module is connected I get around 3 V for all colors, but 0.1 A for the Red and much lower results (more than 10 times smaller) for green, blue and white.
I tried swapping transistors/cables/pins/everything in any possible way. Nothing changes.
I tried adding multiple transistors in parallel. Voltage stays the same, current doubles and also the light emitted by the led. The problem is, just to match the red I would have to use 10 transistors for each other color. Doesn’t seem viable. Also, haven’t seen anyone fitting so many transistors into their lightsaber, so I must be doing definitely something wrong. The problem is, I don’t know what...
Help 