I was told that I could find a lot of help from friendly people here... I am very new to Arduino, and I have been teaching everything to myself so far, and so far I've gotten pretty far. My current project is based on some, lets call them LED strips, that I have that I would like the arduino control. They are RGB and have a wire for each color, and one common wire. With the stock controller for the LEDs, i used a multimeter (which I barely know how to use), and figured the voltages are 14.0-14.2v.
Heres where I am: Since the LED strips use R, G, and B to create colors, I wired up 3 leds, and 1 push button to the arduino and created code to have these modes: RGB, R, G, B, RG, GB, RB, RGB "strobe", Police lights, R Fade, G Fade, B Fade, and Rainbow fade. I based my code off of a bunch of other tutorials and it works fine. So now I'm on to the next step, connecting these 14v LEDs
How do I go about this? Will I still be able to use pins 9-11 to "fade" them? Or will I have to go about this differently since there is more voltage being used?
You need to use a transistor or a FET to switch them under the control of the arduino. You will also need a source of 14V. Are you sure about that value because they are normally 12V strips.
I went to RadioShack and picked up a (cheap) multimeter and touched the terminals of the strips, they registered at 14-14.2v, so I'm going to assume that should be right..
The application will be in a car, so I have the power available... However I have no clue how to harness it and pump it towards the arduino/LEDs
this FET thing, whats that? Sorry, but I have more understanding programming this thing, than actually hooking up the hardware...
Basically, the Halos in my car are controlled by a unit under the hood, however, the control unit is very restrictive and won't allow me to customize the animations. After doing tons of research, the only solution I could find was arduino. Now after programming this thing to control single LEDs, I'm sure it shouldn't be to hard to port it over to these 14v LED "strips"
Just to Cover My A** (and yours), Keep in mind that here in Arlington where I live, it's a $250 fine for having colored lights on while driving, and this applies to strobes, neons (undercar or otherwise), blue and purple HID's, and basically any other lamp that is not "standard". Also, HID's in reflector lenses instead of projectors also get lumped into that violation group. Check with local laws if you intend to use these for anything other than car shows.
OK, that said.
You will need a FET triggered by Arduino's 5V output to switch the 14V going to the LED strips.
Well not quite as simple as that because you need to switch the 14V anodes. So you need a p-channel FET and an NPN transistor to drive it. One of these combinations for each channel.
Yes although you could get away with a smaller transistor like a 2N2222 and also get them from the same place to save on postage. You will also need a resistor, a 4K7 for the base of the transistors and a 10K from the gate to the positive supply of the FET.
Also, a 9 or 12 volt regulator to convert the 14.4 car voltage to the 7-12 volt input for the arduino. 9 volts is the suggested input, so I would use a 9 volt reg. Also, you'll need freewheel diodes and filtering capacitors on the leads to keep noise from the alternator out of the arduino, as well as any freewheeling voltages from un-dioded coils/inductors.
Also, you cannot "fade" an LED. LED's are a steady-voltage input, and cannot be de-voltaged like an incandescent bulb. You can PWM them to an extent to "fade" them to the human eye, but if you go too far, it will look worse.
you cannot "fade" an LED. LED's are a steady-voltage input, and cannot be de-voltaged like an incandescent bulb
Yes you can. An LED / resistor will increase and decrease in brightness as the voltage across it increases and deceases. This is because the current changes dependent on the voltage. That is what the resistor does for the LED.
Also, a 9 or 12 volt regulator to convert the 14.4 car voltage to the 7-12 volt input for the arduino.
No the arduino is quite happy running off anything up to 24V. The recommended 9V is only recommended to minimise the heat dissipation in the regulator. As the arduino is not going to be supplying much current to the external circuits this is minimal.
Also, you'll need freewheel diodes
No these are only used on inductive loads like motors.
filtering capacitors on the leads to keep noise from the alternator out of the arduino
While the arduino has built in filter capacitors adding extra ones would not go amiss but see if they are needed first.
You can PWM them to an extent to "fade" them to the human eye,
you cannot "fade" an LED. LED's are a steady-voltage input, and cannot be de-voltaged like an incandescent bulb
Yes you can. An LED / resistor will increase and decrease in brightness as the voltage across it increases and deceases. This is because the current changes dependent on the voltage. That is what the resistor does for the LED.
I think he is talking "fade" as in having code fade an LED from off to full brightness and back again. Doable with PWM, but at some point, the human eye will catch the frequency and it'll look like a blinking light at low frequency.
Also, a 9 or 12 volt regulator to convert the 14.4 car voltage to the 7-12 volt input for the arduino.
No the arduino is quite happy running off anything up to 24V. The recommended 9V is only recommended to minimise the heat dissipation in the regulator. As the arduino is not going to be supplying much current to the external circuits this is minimal.
I'd still be leary, IMO.
Also, you'll need freewheel diodes
No these are only used on inductive loads like motors.
I know alot of relays on cars aren't dioded, especially those added aftermarket. Amplifiers also can feed back AC into the the system. I just likehaving them to keep positive voltage from coming in the negative line, and negative in the positive line.
filtering capacitors on the leads to keep noise from the alternator out of the arduino
While the arduino has built in filter capacitors adding extra ones would not go amiss but see if they are needed first.
I like having them for reasons stated above.
Not trying to start a fight, just my observations from dealing with stereo systems and race cars. (Our race car, FYI, puts out 18V AC overlayed 16VDC on a 12V rated Chevy alternator..Thus why I prefer having regulated and protected input. Went through 3 logging computers before we discovered it. But some of that might be backfeed from the ignition box that a streetcar wouldn't have.)
