I'm creating an emergency light bar that's controlled by an arduino micro.
I want to power everything from a car's cig lighter, so I have 12 volts to work with.
Using an online resistor calculator, I figured out how to operate each group safely on 12v.
For now, I'll only ever have 2 groups of lights on at the same time. Since each group would be wired to run on 12v, would the lights become dim? Is that the same thing as using 24v?
If not, then what is the best way to power the arduino? I've seen step-down converters brought up a lot. I've also seen "smoothing" mentioned a lot.
It is generally not practical to use resistors to control the voltage in a power circuit.
If you want useful advice you need to post a diagram showing how you propose to connect everything.
What Arduino are you proposing to use?
What type of lights are you proposing to use? And how many of them?
...R
If you're not that worried about power consumption, I've used a DC-DC buck converter from eBay for a dollar or two. I've adjusted the potentiometer on it so that with 12V input I'm getting 7.2V of output and then fed that into the Arduino's on board regulator through the power jack. For the lights, I take the power from the 12V side of the converter. You will need to have a common ground between the Arduino and the 12V circuit.
If you want something more efficient, you can replace the on board regulator with a more efficient one that can deal with a higher input voltage like these.
Given that you're running off the car's power supply I'm guessing a little extra power consumption compared to what the lights are using is probably not a problem.
I'm not worried about power consumption, I'm only worried about cooking my arduino, and not having enough power to run everything.
Each block of lights (18 LEDs), can safely run on 12v. If I have two of them on at the same time, wired in parallel, would the lights dim?
The red blocks are wired like this: LED Calculator - Current limiting resistor calculator for LED arrays
What's the best thing to put between the arduino and the 12v cig lighter?
Are you going to run the car engine with this setup? If so, better allow for up to 14.8 volts after starting the engine and the battery is being recharged.
By the same token, all modern cars have such small batteries, everything is turned off while starting the engine, then back on once the engine is going. This will cause a reset on your Arduino.
Paul
It's going to be powered through a car's cig lighter port. Will I still get the voltage spikes?
This doesn't need to be on all the time. I'm going to be wiring a switch into the circuit so I can turn it on and off.
Simplest solution would be to get yourself a cigarette lighter to USB converter to power the Arduino then use something like a small relay to turn on the LEDs directly on the car's 12V supply
MrJaWapa:
It's going to be powered through a car's cig lighter port. Will I still get the voltage spikes?
This doesn't need to be on all the time. I'm going to be wiring a switch into the circuit so I can turn it on and off.
You will still get the battery charging voltage, whatever it happens to be. And, of course, it will be on and off and back on when you start the engine. The USB adapter is the best option in my opinion.
Paul