Would it be legal/possible?

[tomy]

I was wondering if it was possible to take 12V RGB LED Strip and plug it directly into the PD board to light up the robot. The RGB Strip has a 12V connection but I cant seem to find the ground. Is this legal / possible?

[RufflesRidge]

Originally Posted by tomy

The RGB Strip has a 12V connection but I cant seem to find the ground. Is this legal / possible?

You're going to need to find the ground before you can really do anything. Do you have a part number/datasheet?

[tomy]

This is the exact LED strip I have:

http://www.adafruit.com/products/285...roducts_id=285

[Ben Wolsieffer]

If you just want it to show a single color, you should just be able to plug the +12v wire into the positive on the PDP, and the R, G, and/or B wires (in any combination) into the negative on the PDP.

It would want more control, I would recommend using an Arduino and some transistors to control the channels with PWM. You could also try using the PWM outputs on the roboRIO, but their low frequency might cause come flickering.

This Adafruit tutorial should help with wiring the transistors to an Arduino (or to the roboRIO PWM outputs).

[Mr V]

There are 3 ground wires, one for each of the different LEDs in each light. IE one for Red, one for Green and one for Blue. Depending on which one(s) you ground and how frequently they are cycled on and off you'll get the different colors.


How it all works is explained in the first paragraph of the description.

[tomy]

So it would be legal to wire it directly to the PD Board

[Mr V]

Originally Posted by tomy

So it would be legal to wire it directly to the PD Board

Yes if the gauge of the wire used meets the minimum for the breaker feeding the circuit, or if you provide additional circuit protection appropriate for the gauge of wire in the circuit.

Of course connecting it only to the PDP you'll be stuck with only Red, Blue, Green, the color that will result from driving two of those colors at 100% duty cycle or white if you connect all three grounds.

Now there is nothing that says you can't use a micro controller and some transistors to create a custom circuit to very the duty cycle of the separate colors.

[GeeTwo]

Originally Posted by tomy

So it would be legal to wire it directly to the PD Board

Yes, but you would not be able to have the colors change without relays or other switching. If you aren't interested in "shades", but just being able to switch among the eight colors (off, red, green, blue, magenta, yellow, cyan, white), you can use 3 DIO ports and a relay module similar to the following:

http://store.linksprite.com/dc-5v-four-channels-relay-breakout-with-optoisolator/ (You would only need to use three of the four relays). We are planning to do something very similar to this to display our alliance colors during matches, green (our school color) during practice, and perhaps a few others occasionally.

[kgzak]

Originally Posted by tomy

This is the exact LED strip I have:

http://www.adafruit.com/products/285...roducts_id=285

Those are common anode LEDs meaning that they share a common 12v and have 3 different grounds. One for each color (Red, Green, Blue). Adafruit has a tutorial that can teach you everything you need to know here:https://learn.adafruit.com/rgb-led-strips/overview

[Ben Wolsieffer]

You should be fine as long as they are simply dumb (ie. not digitally controlled) strips. Keep in mind that they will dim when your battery voltage drops.

I don't really understand what you mean by saying you can't find the ground. The LED strip should have two wires, one black and one red. They should go into the correspondingly colored ports on the PDP. A part number/link would be helpful.

[Sohaib]

Originally Posted by lopsided98

Keep in mind that they will dim when your battery voltage drops.

You can always connect it to the VRM to alleviate this. The VRM will to some degree regulate the voltage so that when your battery may not be providing a constant 12v, the VRM will do it for you.

[Ben Wolsieffer]

Originally Posted by Sohaib

You can always connect it to the VRM to alleviate this. The VRM will to some degree regulate the voltage so that when your battery may not be providing a constant 12v, the VRM will do it for you.

In this case though, you will need to make sure to not exceed 2 amps. We didn't have that many LEDs last year, but when they were displaying bright white, we used around 3 amps.

[Sohaib]

Originally Posted by lopsided98

In this case though, you will need to make sure to not exceed 2 amps. We didn't have that many LEDs last year, but when they were displaying bright white, we used around 3 amps.

The highest current outputs labelled on the VRM are 2A.

[Ben Wolsieffer]

Originally Posted by Sohaib

The highest current outputs labelled on the VRM are 2A.

Yes, that is why I warned about not exceeding 2 amps.

[Tungrus]

Just a reminder, VRM's 2A rating is peak, nominal is 1.5A.