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Topic: 2 Power supplies in the same panel (Read 391 times) previous topic - next topic

sayedmosalem

I'm making a control panel which contains multiple Arduinos, AC-Relays, SSRs ..
I have decided to use 2 power supplies 1- 12V PS 2- 5V PS

5V PS will go to relays and I/O pins for Arduinos
12V PS will go to the Vin for Arduinos

V+ for power supplies will never be together in any points and I have check this.

When I tried to power up the panel all Arduinos is powered OK but the 5V power supply is generating only 0.5V (I' connecting the ground of the 2 power supplies together)

when I disconnecting the jumper between the Grounds of the 2 power supplies, I got 5V .

Does anyone knows why this happen? and should I buy a board or regulator from 12 to 5 volt and remove the 5V PS??

thanks

Grumpy_Mike

Quote
Does anyone knows why this happen?
It happens because of something you are not telling us. What you describe is perfectly reasonable but it is obvious that is not all that is going on.

When you say:-
Quote
5V PS will go to relays and I/O pins for Arduinos
What do you mean? Are you connecting the Arduino's 5V line to the 5V power supply? If so don't, that is your problem.

sayedmosalem

about 5V .... I mean that some input pins for the Arduino will take 5V from the power supply through the relay (if something activated the relay)
Vin pin for arduinos is connected to the 12V PS

Mikeb1970

Could you possibly provide us with a schematic drawing of your project? Because I don't even have a remote clue of what your meaning, just scan a simple schematic you made or quickly make something that can inform us. What I am able to tell you sofar is, that if you claim that you remove to connection between the two GND's and everything works ok, is that you have made an error there, possibly causing your PS triggering some kind of protection.

With regards,

Mike

sayedmosalem

I have attached a hand sketch which has a sample from the project
thanks

Southpark

#5
Dec 12, 2017, 10:37 pm Last Edit: Dec 13, 2017, 03:56 pm by Southpark
I have attached a hand sketch which has a sample from the project
thanks
For the 5V power supply, there is one '-' terminal and two '+' terminals. What do each of those represent? Why does it have three terminals?




In many cases, the '-' terminals of the power supplies need to be electrically connected together.

You might need to just disconnect the circuit (ie. arduinos, relays etc) from the power supplies, and then ONLY test the two power supplies to begin with. Connect the negative side of both power supplies together, and then measure the supply voltages. If everything is ok, then you have a wiring issue or circuit issue ---- which means something is wrong with the circuit or wiring in the circuitry that you're connecting to the supplies. So either you're doing something wrong with the wiring, or one or more of your components is faulty.

Grumpy_Mike

about 5V .... I mean that some input pins for the Arduino will take 5V from the power supply through the relay (if something activated the relay)
But according to the diagram you posted their is no pull down resistor so either the diagram is wrong or it dosn't work.

Also the label on the diagram says "ground is connected" so why is their not a line that represents that connection?

TomGeorge

#7
Dec 13, 2017, 03:06 pm Last Edit: Dec 13, 2017, 03:11 pm by TomGeorge
Hi,
I think we need to see  picture of your project so we can see your component layout please.

Can I suggest you sit down and do a comprehesive schematic, it sounds as though you have built, but not done any paper work as you go.

What is the spec/data on the relay board and the SSR and both power supplies?

Can you tell us your electronics, programming, Arduino, hardware experience?

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

terryking228

Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

MarkDerbyshire

V+ for power supplies will never be together in any points and I have check this.

Not true

From that drawing when the relay is in the NC position you have connected the 5V positive to the UNO 5V positive which is from the 12V supply.  The UNO nor the power supplies are not isolated from either.

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