Overvoltage Power Supplies. 5v 10a

Projects General Guidance
1

I'm powering an ESP32 from the vcc pin and also a string of 177 RGBW Neopixels. Both are very voltage sensitive. In the Neopixel documentation it warns against anything over 6v, and I can confirm that they begin to malfunction past this threshold.

I'm having a lot of trouble finding a true 5v power supply.
The sticking point is that the Neopixel string can theoretically pull 14amps, even though it never will. So I've had to beef up all the wire gauges and electrical components. I landed on ~10 a capacity with an 8a fuse as an acceptable solution.

The problem is that every single 5v power supply I've tried outputs 7.5v.
Removing 2v wouldn't normally be an issue, except for the amps.
I can't find a way to get rid of those 2v.
I can put 5 10a Diodes in sequence and hope none of them fail.
I can't use a regulator because of heat. Also if you add additional components to the circuit, it brings the voltage too close to the dropout and the regulator can output 4v.

I've tried direct supplies, regulated supplies and switching supplies. Here are 3 of the 5 I've tried.

Then I tried one of these.
I put one of the "5v" 7.5v supplies on it. The threshold wasn't met and it output 0v.
I attached a 12v supply to it (which is actually 17.5v) and it outputs.... 7.5v

I know that a more appropriate supply would be something like this But this form factor is not safe for my use-case.

Can anyone recommend an accurate supply that is fully enclosed and relatively portable?

2

Check those power supplies for an adjustment pot. I would be surpriced if a 5 volt pwr supply is "nailed" to 7.5 volt. So faar I've only bougth 12 resp. 24 volt supplies from Ebay && Co, and they have been civilised, not running wildly, and they have adjustment pots.

3

Railroader:
Check those power supplies for an adjustment pot. I would be surpriced if a 5 volt pwr supply is "nailed" to 7.5 volt. So faar I've only bougth 12 resp. 24 volt supplies from Ebay && Co, and they have been civilised, not running wildly, and they have adjustment pots.

They're all enclosed in plastic shells. Do you mean crack them open and look?

4

Now having a look at those links I doubt that stuff is even stabilised. Looks like transformer, rectifier and a large cap.
Look for stuff looking like this 24 volt supply: Geekcreit® ac 110-240v input to dc 24v 17a 400w switching power supply driver board Sale - Banggood.com

5

Dr-Zee:
They're all enclosed in plastic shells. Do you mean crack them open and look?

I've got a few like that and they have pots for adjusting, but You wouldn't miss that I think.

6

It is highly unlikely that any of the supplies you linked to are outputting more than 5.5volt.

Most likely that your DMM is the problem. Did you check it's battery?
A flat battery can cause the readout to increase. Happens to one of my cheaper meters.

Measure the voltage of a fresh 9volt battery to confirm.
Leo..

Edit: You of course don't crack open sealed supplies, and you likely don't find an adjustment pot in there.
Only 'metal frame' supplies have adjustment pots, but they are factory adjusted to the rated voltage plus maybe 5%.
A regulated 5volt supply (universal mains voltage is a hint) is never 7.5volt.

7

DMM running low on the battery ought to either blink a symbol or the LCD display goes out but surprises never end.

8

I'll replace the batteries in my MM and see it that's it.
There are no visible pots on the supplies but I might crack one open for the heck of it.

Thank you both very much.

9

Make sure Your DMM is in order before thinking about ruining those pwr units. They might be okey!

10

You were right, it was my DMM battery. That was an expensive oversight.
Thank you both very much for your help.

11

Dr-Zee:
You were right, it was my DMM battery. That was an expensive oversight.
Thank you both very much for your help.

I say thank You both as well. Using DMMs for a very long time I never experienced this. The cheep ones from China..., one never knows.

12

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