Need help controlling voltage/current/colors in a RGB string blade.

[sligs78]

I need help controlling voltage/current/colors in a RGB string blade. It's going to be a temporary direct drive saber until I get a small arduino later.

I used some small potentiometers with resistors to control the colors coming off a 3.7 volt source, but the small potentiometers aren't rated for a lot of power. I then ordered some P-MOSFETs (part# FQP27P06) to combine with the potentiometers to control the current, but I found I needed about 5 volts to get the amount of current I wanted. I have a 7.4 volt battery, but I would need a large wattage resistor, and I don't want to waste a lot of power using it.

Each color will have to be controlled and would need about 0.85 amps going through each leg. The blue and green colors are rated 3.1 volts while the red is rated 2.1 volts.

Does anybody have any suggestions? Would I need 3 different buck pucks?


RGB string setup looks like this.
E0Tyytl.jpg

[jbkuma]

If you are happy with your color, measure the resistance value for your pots then use the appropriate resistor. I'm using the main, FOC and sleep pads off of a NanoBiscotte to signal a Pro Mini to control some neo pixels accents with transistors for my main RGrB TriCree. It's the best of both worlds as far as I'm concerned.

[sligs78]

I'm trying for a color change saber.

[FenixFire]

I'm trying for a color change saber.

Pots or simple slider on-off switches are basically your options without micro-controllers then.

[Thalan the Exiled]

There are some really cool super small 3 way slider switches on ebay. I use them with a tri reb
RGB to get some color mix/change with a NBv2. Have to open blade holder to access them but they work great. Just had to figure the right resistor. They are small enough you could probably fit 2 in and have even more options.

[jbkuma]

Since you are already considering it, even if you have no arduino experience, it really might be easier to do it right the first time. You can get a pro mini for like $5, or even a nano since you are using 7.4v battery. You already seem to know how transistors work, I didn't when I started a few months ago. Setting up a pwm color control was a project I learned on my first day of arduino coding and my project is by far the most serious bit of coding I've ever done outside of a website.

For guidance on that sort of thing, your best bet is tutorials on the arduino and adafruit sites, arduino development threads are frowned upon here.