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Topic: Running Arduino on 12v + running load on same 12v? (Read 784 times) previous topic - next topic

iisfaq

Hi all

I want to run my Arduino Mega on a single 240v to 12v DC supply that I have.

The 12v DC output is rated at 1a

My circuit will be quite simple:

* Power Arduino Mega - it will run Ethernet, RTC Clock, and a Relay board used to turn on and off the solenoid
* Power a 12v solenoid - seems to pull about 300m-500ma (not sure of the startup current) - see http://nicegear.co.nz/robotics/12v-solenoid-valve-34/

The relay board is from EBAY - see http://www.ebay.com/itm/1-Channel-5V-Relay-Module-for-Arduino-8051-AVR-PIC-DSP-ARM-/180982430549?pt=LH_DefaultDomain_0&hash=item2a2364bb55

Directly wiring up the solenoid to the transformer seems to work fine turning it on an off.

I am planning on just splitting the 12v between the Solenoid and Arduino.

My question is how much of a drain does this put on the Arduino? Could it cause it to lockup while switching on/off?

Should I add any sort of "protection" to the Arduino side of the power supply?  If so what?

Cheers

Chris

Osgeld

if its not crowbaring the power supply it will be fine, as far as protection you want to throw a diode across the solenoid ( cathode to + side, anode to - side) so it wont spit out back EMF on your power lines causing spikes and noise

otherwise your arduino's voltage regulator might run a little warm, but it should be fine as it has protection in the IC
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

iisfaq


if its not crowbaring the power supply it will be fine, as far as protection you want to throw a diode across the solenoid ( cathode to + side, anode to - side) so it wont spit out back EMF on your power lines causing spikes and noise


Thanks for the info - any ideas on the spec of the diode? or maybe a part # for me to look into?

Chris

iisfaq


otherwise your arduino's voltage regulator might run a little warm, but it should be fine as it has protection in the IC


I have also purchased one of these:

LM2596 DC-DC Step Down CC-CV Adjustable Power Supply Module Output DC 1.5V-35V

http://www.ebay.com/itm/LM2596-DC-DC-Step-Down-CC-CV-Adjustable-Power-Supply-Module-Output-DC-1-5V-35V-/250954117473

Not sure if I need it since I am unsure if this is better than the simple Voltage Regulator on the arduino?

Would it be worth putting this inline?

Chris

Osgeld

#4
Oct 01, 2012, 07:02 am Last Edit: Oct 01, 2012, 07:20 am by Osgeld Reason: 1
Quote

Thanks for the info - any ideas on the spec of the diode? or maybe a part # for me to look into?


just your standard black 4000 series power/rectifier diode, its not going to carry load, its just going to provide a short when the electromagnetic field collapses and sends a 100v + pulse back down the line.


Quote
Not sure if I need it since I am unsure if this is better than the simple Voltage Regulator on the arduino?

Would it be worth putting this inline?


oh its better cause its not burning off the extra voltage as heat, and if its worth it or not depends on how much current is demanded of the on board regulator and how hot its getting.

the basic rule is stick your finger on it, and if you can hold it there for 5 seconds or more its not too hot. The datasheet says max 150c junction temperature (the chip itself, not the case)  with a 15c per watt junction to case difference ...if you wanted to run the maths and figure it all
http://arduino.cc/forum/index.php?action=unread;boards=2,3,4,5,67,6,7,8,9,10,11,66,12,13,15,14,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,86,87,89,1;ALL

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