An inexpensive bench-top 12v Power Supply

[XS650]

Originally Posted By: brianl703
Originally Posted By: kc8adu
use a good power supply and you wont have the noise.


What I've heard is that unless that power supply costs at least $40, it's probably a piece of trash.


Having handled cheap power supplies ans good power supplies, I think there must also be some Watts/pound ratio that indicates trash. The lower the higher the number, the trashier the supply.

 

[Quest]

Having handled cheap power supplies ans good power supplies, I think there must also be some Watts/pound ratio that indicates trash. The lower the higher the number, the trashier the supply. [/quote]

Urr, not really. In reality, good quality 'lytic capacitors may weight just as much as the trashee ones, and so are the ferrite core transformers.

Weight differences may be as much as several 10s of grams and not by much. The rest of the contributing weight differences maybe thicker/heavier gauge aluminium heat sinks, cosmetic (thicker gauge cases, etc.)

Q.

 

[SecondMonkey]

I think you guys are over reacting about the power noise factor. The intent of this post was a simple cheap bench supply for testing things. For that it works great. If you intend to run some high power sound system from it, just use a 110v amp.

 

[Jim 5]

Originally Posted By: kc8adu
to the o p.
the bestec blow em up special unit you built your project around needs to be recapped.
the design is ok but the beancounters made sure the cheapest parts were used.
in the world of smps and low esr lytics cheap and good are mutually exclusive.
you can ask any emachines owner about that bestec unit.
poof!
since that unit has +5 and +3.3 remote sense it wont suffer as badly as some with no load on +5.
if you can provide a few amps load on+5 it will stay closer to 12v.
but recap it first!
the most important are the 10@50 and 220@25 next to the +5stby transformer.


Thanks for the help!

Is there anyone that can help me understand what is trying to be communicated here? I am not technical enough to understand.

 

[tom slick]

he's saying you should replace the capacitors in the power supply with higher quality units.
just a guess

 

[eljefino]

This is awesome, too bad it's not that easy to charge car batteries.

Maybe I could take the -12v and the +3.3 to make a redneck trickle charger.

The only hack I've done so far is a 5v out to run a wifi adaptor that runs only when the computer is on.

 

[brianl703]

A 500W power supply ought to weigh more than a 300W power supply. If it does not then it's quality is suspect.

 

[brianl703]

Originally Posted By: eljefino
This is awesome, too bad it's not that easy to charge car batteries.

Maybe I could take the -12v and the +3.3 to make a redneck trickle charger.


http://www.qsl.net/9w2lw/power.htm

Shows how to mod a PC power supply for 13.8V.

 

[meep]

I've used a junked PC PS for years in the garage to run radios, charge batteries, and exercise plenty of electronics. I've never had a problem with noise, whine, etc.. Switching supplies by their nature have these harmonics, but A) auto parts have lots of filtering B) as a benchtop supply I've never had a problem.

NOTE: Seems like they rectify to 3-400 Volts internal before going through the PWM driver. That means HIGH VOLTAGE inside.

Mike