I have an auto watering and cooling system with 1-DHT11 Sensor, 3 -12V Cooling fans, and 1 - 12V Solenoid Valve controlling via 4 Channel Relay Module. Only I Have a 12v 20A power supply to power it.
My question is Can I use a 12v 20A power supply to power Arduino Uno Via DC 12v Jack?
And will it burn or some issue?
no problem. but don't try to power any relay or fan from +5V line of Arduino board.
Not sure I agree.
If more than 1 or 2 of the 4 relay channels are engaged at the same time, the Uno's regulator could overheat and be damaged. This is because the relay coils would be powered from the Uno's regulator.
I'm assuming here that the relay board is 5V, because @prabha95 did not say otherwise. If the relay board is 12V, then no problem because the relay coils would be powered directly from the 12V supply.
If the relay board is indeed 5V, then rather than replace it with a similar 12V relay board, I would recommend replacing it with 4x MOSFETs such as IRLZ44. Don't forget to add 10K pulldowns to each Arduino pin controlling a MOSFET and to add flyback diodes, such as 1N4004, across the fan and solenoid terminals.
12V is a problem for the Arduino, if you try to drawn significant current from the Arduino 5V output.
Electrical noise from motors, relays, solenoids can also be a serious problem, so it is much better to power the Arduino from a 12V to 5V buck converter, via the 5V pin.
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Be careful when using the power plug or Vin. Powering through Vin or the power jack means that the Arduino and all peripherals that are on the 5V rail are powered by the onboard 5V regulator. The on board 5V regulator is not heat sinked so will supply limited current before it overheats and shuts down. The amount of current depends on the voltage input to Vin or the power jack. The higher the voltage the less current can by supplied. I would use a buck converter to drop the 12V to 5V and connect that to the 5V on the Arduino, bypassing the, weak, 5V regulator. Then the rated current of the DC DC converter is available on the 5V line.
Sure. Arduino will only sip the current it needs. Having said that, it will sip too much like a college grad party if you tell it to by powering external devices through the Arduino, as others here so wisely point out. My point assumed you already were powering external devices through dedicated power lines and just tying all the grounds together (as is best practice, I think).
My relay boards use optoisolation. I wonder if prabha95's also do?
We don't know. The point I was making is: how are the relay coils powered?
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Many do. But they often offer the option (via jumper) to power the relay coils from the Arduino, which can pull rather too much on modules with a lot of relays.
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I always thought of 5 volt to power Uno as being anemic. It's handy for USB connection to PC for serial comms and digital sensors in but isn't 7 volts the minimum recommended?
What am I missing? For reference, I have avoided the 5v VIN pin like the plague since I wired one up wrong and damaged an Uno, I always go to the barrel jack because I always have a million wall warts around I can pillage for their barrel jacks.
Ah, yes, I forgot about that. Cheers!
You thought wrong. Powering it with 5V is perfect. Uno is a 5V device.
I hear ya. I had forgotten about the jumper option on these boards, as wildbill pointed out to my response.
Powering through the barrel jack means using the on-board voltage regulator which has no heat sink and therefore overheats easily. That's where the 150mA limit on the Uno comes from. USB gets you 500mA (though it would be unwise to pull that much through thin Arduino traces) and Vin can similarly handle more current.
Only if using the Vin pin or barrel socket because they connect to the onboard regulator. The 5V pin bypasses the regulator.
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I like the barrel socket. It's a nice, solid connection that's easy to swap out. I find the little pin on the board tough to see if I just want to pull the power to swap something else out quick. That's just me.
I hear ya but you know what? I've never had this issue on an Uno or Mega. I am always very careful of current when it's attached to USB, more because I fear for my PC than an Uno. Nevertheless, wise advice, wildbill, wise advice.
You could fit your own barrel socket to the 5V & GND pins, like if you were installing the Uno in a case or something. But be sure to mark that socket "5V ONLY" because unlike the Uno's own socket, it could not handle a range of voltages, the voltage would need to be pretty close to 5V, like 4.5~5.5V. Any more would damage the Uno.
Relays are 5V, All The 12V actuators powering via power supply,
all 5V Requirements are supplied via 12V-5V Regulators.
I am not going to use any 5V Requirments From Arduino board
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Ok then, no problem. But you can get away with powering a few low-current devices from the Uno's 5V pin, such as the dht22 or the gates of MOSFETs, which need almost zero current.