5v power pack.

Attached are some pictures of the circuitry of a 5v power pack I’d like to use to power a compact project.

First, the USB A socket;

I assume I can just solder wires to the soldered connections and run those to my Arduino +5V and GND? That would enable me to leave the USB port available for programming. Do I need a capacitor between the power supply and the Arduino (I’ve seen this recommended somewhere...)

If the socket is thus left untouched on the power pack, it could be available for the user rot recharger their phone or similar. Is there some way the Arduino can Monitor the load on this socket and reduce its power drain (turn off the LEDs) when it is in use?

Second, the micro USB socket;

Really just for recharging the battery...but...again is it possible for the Arduino to Monitor it’s use and again turn off the LEDs if the battery is being charged...or is that even necessary? I don’t want things bursting into flames!

Attached are some pictures


GrooveFlotilla: Okaaay

Yeah, well,

  1. Images too big
  2. When I resized them "You made too many posts in 5 minutes"
  3. When I came back and try again "Your image failed the security checks, please contact the administrator"


GreyArea: Yeah, well,

  1. Images too big
  2. When I resized them "You made too many posts in 5 minutes"
  3. When I came back and try again "Your image failed the security checks, please contact the administrator"


I would suggest imagebin https://imagebin.ca/

like pastebin but for images.

Thanks for that helpful hint…photos as promised…



GreyArea: 3. When I came back and try again "Your image failed the security checks, please contact the administrator"

An indication the file contains personally identifiable information.

For example, did you take the picture using an Apple iPad Air?

How far were you from Carnevale when you took the picture?

OPs pics.

Tom… :slight_smile:

That happens to me when I use GIMP to resize a picture to reduce load on the forum server, if I export the molested file as PNG, it works OK.

Hi, I use Paint to resize and have never had any problems. I always save a jpg.

Tom... :)

Can see Carnevale from my house and yes I’m on an iPad. Not sure how much use those snippets would be to anyone, but understand you have to protect those more vulnerable than me so thanks, PNG’s from now on.

Now, where I DO need protection (from myself) can someone please reassure me this isn’t going to burst into flames! I’ve already extended out the board with the USB ports on (photo);


Just need to wire battery to Arduino...question is, is it safe to go direct to the battery or should I solder from the USB terminal on the board? My assumption is that the board manages load somehow...I’ve confirmed it still works...blue led on board when in use, red when charging...if I draw load from the usb terminal for the Arduino, will the led on the other board still come on?

Also, thinking of putting a switch on the Arduino power feed...is a simple two position switch on the 5v line from the USB sufficient?

Lastly...any one point me to a guide for which two of the four terminals on the USB plug are +5v and GND...and maybe some clues to what the other two do?

Thanks all...

You cannot power an Arduino with 5v and then also connect it to USB - this can damage the board as the two supplies won't agree on precisely what voltage 5v is. I recommend running 5v in only through the USB port, as that physically prevents you from connecting it to USB while it's powered by an external 5v. You might be able to do it if you modified the USB cable and cut the +5v line in the cable... I'm not even certain that would work on all boards though... I don't know how the 16u2 reacts to VBus not being connected.

You cannot power it directly off the battery. The battery is not 5v (it's probably a 3.7v LiPo). That PCB has a boost converter to get 5v out of it.

Switch in the +5v supply is a perfectly fine way to turn power on and off.

The behavior of the LEDs on the power pack board will not change when connected to Arduino - why would you expect them to? If the power draw from the LEDs is a problem, remove them (it's pretty easy to scrape the lens+die off of SMD LEDs such that they're an open circuit)

Right, so, in order;

I can’t use the micro USB on the Trinket if it’s getting its power from somewhere else. Gotcha. Is there some way of the Trinket “recognising” that it’s had a USB cable plugged in and disabling the other 5v line? Probably not cos if there’s any delay between switching the board would reset I guess.

No equivalent of;

If (usb plugged in) and (+5v connected) then (ignore/disable power from USB)


Next, direct connect to battery...yes I didn’t think that would be sensible, thanks for confirming.

As to LEDs on the board...I’m fine with them working actually, just wasn’t sure they’d pick up the load from the Arduino but I guess if I’m taking the wires from the USB socket, I’m not “skipping” any important electronics that might be doing the detecting.

Thanks Drazzy...now, looking at that pic of the PP board...which terminals on the USB are +5v and GND?

And just to be DOUBLY sure (I’m very new at this); +5v goes to BATT and GND to GND on the Trinket? I assume the LEDs have to share GND...is it better to take the LEDs from the PP board or is it ok to use +5v from the Trinket?

And I keep asking...any other bits I should add for protection in case of surges or whatever? Don’t think anyone’s answered yet...sorry if they have and I missed it...