Does anyone know what the max amperage input is on the Arduino for the DC input? The specs show the voltage but nothing on Amps. Should I just go off the datasheet for the micro controller and forget about the rest of the circuit?
Thank you in advanced!
Peter
The Arduino itself uses less than 100 mA so that's a good minimum. The USB connection can provide 500 mA so that's a good target. The regulator can stand about 1 A so that's a good upper limit.
Okay, I looked at all these items and made an assumption of a 1A max. Just wanted to see if there was a solid number. Thanks for the reply!
As long as you are supplying the correct voltage, having more amps available than is required is not going to cause anything to happen. The Arduino board will only use the amps that it needs. Thus the reason that a car battery can power the areduino and it has short busrt availability od 100's of amps.
If you are providing power thru the barrel jack, that current goes thru the reverse polarity protection diode, which I believe is only rated for 1 amp.
CrossRoads:
If you are providing power thru the barrel jack, that current goes thru the reverse polarity protection diode, which I believe is only rated for 1 amp.
Which means that if the Arduino starts drawing close to 1A, we might see this part (or the regulator) fail first. But you can still hook up a power supply rated for more than 1A. Similarly, if you have a 400mA power supply and the Arduino starts to draw 800mA, the magic smoke in the power supply's protection circuits might escape.
Well, I was asking because I intended on useing an ATX power supply to power the Arduino and my project because of the voltage it provides will make an excelent external source for rails. However, if there is an issue that causes either my circuit or the Arduino to fail, the applied Amps being that high will cause a nice poof! So I figure as long as I can do a little regulating in the areas of interest along with a little filtering, I shoulden't run into to many problems in the event of a malfunction.
Fairchild make some nice current/voltage regulators (LM7805(+5v)& LM7812(+12v)) that I think I'm going to use to protect my Arduino and servos , along with some 2200uf caps for filtering and maybe a fuse on the supply rails as well and that should do the trick for a good source of protection against that magic smoke! I'm particularly excited to see that the 5v supply will provide 14 amps, leaving me ample room for servos and other 5v accessories. With the servos clocking in at 8mA current drain at idle. I will have to hook up the multimeter and test what the draw is when the servo is in motion, the specsheet is usless just caliming it's able to pull high current levels. It would be nice to have a number, but I will have to just check it in circuit to know what I will need to give each servo their own line of defense or I have a feeling I will be seeing a lot of servos making their way to the trash, even though the local hobby shop sells them pretty cheap I don't like wasting $15 over a stupid, preventable mistake.
Anyways, thank you for the replies, you guys are GREAT!
As long as as you connecting all the servos & stuff up in Parallel with the arduino, and not trying to make all the current go thru the barrel jack connector and out the 5V header pin to the servos, you will be okay.
The servos can't draw any more current than (source voltage)/(DC impedance), DC impedance being the resistance of all the wiring that makes up their motors, so you don't need to worry too much about them drawing too much current.
So, you think putting voltage regulators in circuit before the servo is a waste of time?
It is not going to protect much. It adds a bit of power supply isolation however in case you get interference from the servo which gets on the rails and upsets the processor. This is a problem we often see here.
Even with the supply voltage of the servos is not running from the Arduino but a seperate supply, it will still cause some interference? I guess I can try and if it causes an issue I can always take them off, I have the parts sitting in my office, I just have not had the chance to put it together... It's been to damn hot up stairs in my office, I'm waiting on my air conditioner so I can park my butt up in there and get back to work. I have been sitting in my living room typing away on my netbook, missing my 3 screen powerhouse of a computer upstairs!
Even with the supply voltage of the servos is not running from the Arduino but a seperate supply, it will still cause some interference?
Not sure I understand this.
The interference is still generated, it is just with a separate regulator it is a bit more isolated from the main supply.
Sitting here at the height of summer with the heating on, its quite cold.
I'm sorry, I read your first comment wrong.... I see what you're saying.