Uno not responding after 'sparking' on main power plug by external project load

Other Hardware General Electronics
1

Thanks guys for the awesome UNO. Most educational. I don't know much about hardware and tried to use a 12v 1amp 240v power pack. It registered 16v open circuit, but came down to about 14v when just powering the Uno. All good so far.

I then with my lack of knowledge tried to breadboard a external load onto the Uno power plug. ie. sharing power... there was a little spark as I touched the external load onto the Uno power plug (direct onto the plug) and the Uno stopped responding to IDE, ie. leds still on but cannot down load code.

I did an awful lot of research and found

which seemed to possibly be the problem. Anyway, spent lots of time and had problems with the Flip USB driver on Windows 7 and eventually blew the board by touching the wrong things together :frowning: (you know, the little 'crackle, pop, smoke thingy')

My basic question is,

'It seems playing around with the power supply to the Uno, while the Uno was ON, reset something in the board so it no longer communicated'

Is there some way to 'short out' any noise, sparks, etc so they don't travel into the Uno via the power supply jack? If so, can you give me a circuit diagram so I can try and implement it with an external project load connected to the Uno power jack?

I only have limited electronics knowledge, but, for example, would you put a small capacitor across the power supply jack to dampen any spurious noise going into the power jack?

Another 'fix' I've heard of is putting a 'kick back diode' across the power supply?

Any thoughts most appreciated.

Cheers,

ps. Thinking further about what I did, if the external load was too big for the 12v 1amp supply it would have pulled down the voltage on the Uno power plug at least when starting up, and may have caused damage that way?

2

Please be careful with all those voltages.
The DC power jack on the Arduino Uno board can have 6 to 20V, but between 7 and 12V is better, and 7.5V is ideal.

If the usb power is not enough, a regulated power supply is the best.
Using a power supply for a lamp can cause a lot of trouble. Or is it a battery ?
If you use the power supply for something else, and the voltage drops, that should be no problem.

If the load is inductive, it could destroy the Arduino board when there is no fly-back diode.
You have to know about this, or you will destroy every Arduino board.

Do you have a 'normal' power supply ?
Can you make a schematic or a drawing of your project ?

3

Thanks so much for your reply. Much appreciated.

Yes, they say, experience is the best teacher !!

In my case, learning to be very careful in mixing Arduino power supply with project power supply.

It was a 1 amp (I think you read it as lamp) 12v powerpack which plugs into 240v with an open circuit voltage out of 16v.

I believe, primarily, when I attached the project to the Ardiuno power supply the voltage dropped momentarily below 5v and destabilised the Arduino (and possible changed the code in the USB processor)

I believe I have learnt my lesson, so generally with further development I will split the two supplies.

Once all is stable, I will attempt to supply power from one source using fly back diode and capacitor and ensuring that voltage does not fall below 5v.

Has anyone any thoughts on the design of the fly back / capacitive filter? I'm not much of an electronics guru :slight_smile:

4

Sorry, I read it indeed as 'lamp'. I'm confused about the powerpack and the voltage drop. Can you give a link to it. Perhaps you should not use it, I don't trust it.

Can you get a regulated power supply ? There are small switching power supplies with regulated selectable voltages.

If you make a photo of your wiring or write it on a piece of paper and scan that, you can attach it to your post. That would make it much easier to check your circuit.

5

AC or DC power supply?

The UNO really prefers DC!

Are you sure you connected it with correct polarity?

6

Peter_I:
AC or DC power supply?

The UNO really prefers DC!

Are you sure you connected it with correct polarity?

There is a diode on the input, you cannot destroy the Ardunio by reverse polarity, it will just not power on. On the other hand, i'm pretty sure, that it would be REALLY unstable, when run on AC!

// Per.

7

solmil:
I believe, primarily, when I attached the project to the Ardiuno power supply the voltage dropped momentarily below 5v and destabilised the Arduino (and possible changed the code in the USB processor)

This will not "change" the code in the processor(s) - They are using non-volatile memory, and a power-brownout will not change the memory contents.

solmil:
Once all is stable, I will attempt to supply power from one source using fly back diode and capacitor and ensuring that voltage does not fall below 5v.

Fly back ? You are not designing a Switch mode power supply, so no flyback here... I guess you meant something else.

// Per.