48" LED Array - Up and Running...Mostly

[hillegom]

How many amps at 12V do you need?

[Ron99]

Originally Posted by hillegom

How many amps at 12V do you need?

Only a couple of amps. The Arduino itself uses very little current, it dependes on what is plugged into it. I will probably only be using it to generate the PWM signal and power a real time clock circuit so it will likely only be using a few hundred milliamps at most. the three fans will probably use more and fans typically draw around 300mA; maybe a little more. So a 2A power supply will likely be more than enough.

Originally Posted by StirCrazy

um, thats stupid, I figured the PWM models would be based on 5V as there is only need for a pulsed signal not a voltage.. oh well.

Steve

Yeah, but I guess they did not design it with microcontrollers in mind. You can apparently use lower voltage but it will not go to full brightness. I am using a 9V battery for test purposes just to get it to fire up. It lights but is probably not a full brightness. It is basically using a 10V signal for full bright that is then chopped up for the dimming.

Originally Posted by StirCrazy

Ron, what about using a 10V power supply to power the arduino, and then taking the power from your 9V out wich will actualy be 10V. this will eliminate that need of another power supply as I can't imagin you need much of any current for the PWM.

Steve

You are correct. I am still figuring out the Arduino and assumed it needed 5V in but it can take 12V in as it has it's own voltage regulator on board. So I can use a single 12V supply for the fans, the Arduino and then with a voltage regulator to supply the PWM. I don't see a 9V out on the Arduino, just a 3.3V and 5V outputs.

[StirCrazy]

Originally Posted by Ron99

You are correct. I am still figuring out the Arduino and assumed it needed 5V in but it can take 12V in as it has it's own voltage regulator on board. So I can use a single 12V supply for the fans, the Arduino and then with a voltage regulator to supply the PWM. I don't see a 9V out on the Arduino, just a 3.3V and 5V outputs.

there is a pin labled Vin it can be used for a hardpoint voltage supply or you can take off there to power something else and it will be what ever power you are feeding your board with.. so if you are using a 12v adapter (which is probably what you should use. it will be 12V out. then you can step it down to 10V as you lose about 0.7 of a volt. so that out with a 12V adapter will actualy give you about 11.3V

Steve

[Ron99]

Originally Posted by StirCrazy

there is a pin labled Vin it can be used for a hardpoint voltage supply or you can take off there to power something else and it will be what ever power you are feeding your board with.. so if you are using a 12v adapter (which is probably what you should use. it will be 12V out. then you can step it down to 10V as you lose about 0.7 of a volt. so that out with a 12V adapter will actualy give you about 11.3V

Steve

I guess it's 6 of one half dozen of another. I still need to run that through a voltage regulator and then a transistor switched by the 5V PWM from the Arduino. So whether it originally comes off the 12V out from the Arduino or right off the 12V power supply probably makes little difference functionally. Although I may be able to do something more compact with a proto shield on the Arduino itself using the 12V Vin as you suggest.

[Ron99]

Quick update. Got all the LEDs wired and test fired. All work fine. Now I need to get some connectors and wire up all the drivers. I am also short a few 60 degree optics. For some reason I thought I had more of them so I have to order up a few more. Arduino parts are ordered and I should have them by the end of the month.

[StirCrazy]

hey Ron, where are you ordering your Ardunio parts from?

Steve

[Ron99]

robotshop.ca which has a 5% off coupon code for the next few days.