help with ac to dc power supply i bought from ebay

[patbb]

hello everyone

I bought some parts from ebay, i wanted to make some cool led signs for myself but i didn't want to have a wall wart.

so i bought these guys.
**broken link removed**

i was very excited to finally receive them (chrismass!! yeah my life isn't too exciting
but as soon as i plug them in with about 1M of resistance as a load, the thing actually start to make a pretty loud noise.
(actually both of them were quiet for a few seconds the first time i plugged them in, then started the noise. now it wont go back to being quiet)

it sound like living next to a power station, that little dzzzzzzzzzzz noise.


So i have a few questions for you,
do you think it is normal?
do you think it is safe? would it still be safe if i put it in a box, leave it plugged in for years on end?
is there anything i can do to reduce the noise?
is there some precautions i should take while using those things?

Please keep in mind i'm very new to electronics, please if you want to help me, keep things on a pre-school level and mention even the obvious things that everyone knows!


thank you!

 

[patbb]

okay, i guess these things are only designed to power 10W led lamps and i cannot use them as a power supply for other things right?

The reason i bought those is because i dont want a wall wart and these are pretty cheap (low cost is very important for me)

if im right with my guess, would you mind suggesting another option that i can easily buy on ebay to power about 50, 3.2V leds?


thank you very much!

 

[Jaguarjoe]

The buzzing could be loose laminations in the little power transformer. I've never bumped into a resistor, cap, diode, xistor or IC that made any noise except for the pop when I accidentally blow up an electrolytic cap every once in a blue moon.

This is probably a constant current power supply, that's what LED's like. You can tell by measuring the current through different load resistances. It should always be around 900ma.

As a last resort, contact the seller.

 

[patbb]

Thank you Jaguarjoe, so this men i cannot use this power supply for whatever project right?


Please take me out of my misery and tell me what should i do,
I want 9 and 12 v power supplies to put inside of my project boxes so i dont have stupid wall wart anywhere.
Now i hope i'm not searching for the right keywords because all i can find is power supplies that cost at least 9$ each.
like this: https://www.trcelectronics.com/12-volt-power-supplies-low-open-frame-1.shtml

but i can find plenty of wall warts that do the same thing for only a few dollars???

so what should i do? should i just buy the wall warts and take out the shell and put whatever's inside the wall wart inside my project boxes?

I don't get why there are cheap wall warts that convert ac to dc and provide 12vd but no internal power supply that does the same thing for the same price.
actually it should be cheaper because they do not need to add the power plug, long wire and plastic shell.

going nuts, ocd'ing on this for the last 3 hours.

thank you!!