Switching power supply

[guidoilieff]

A friend gifted me one of these



The ground output doesn't work. The status led lights up and negative and positive works. I was wondering if there is a way to test it without plugging it to 220v or if I can remove the LED and use the ground connection of the led to connect it to the output ground screw.

Sorry for my english, Im lacking words here.


I know I dont have to mess with AC and that cheap switching power supplys are noisy.


thanks

[bluebunny]

What ground "output"??  That third terminal is for connecting the earth connection from your mains (and if you have a metal enclosure, it should go to a stud or bolt attached to the enclosure with a toothed washer - the mains connection attaches to the same place).

How do you know "positive and negative work" if you've not plugged it in?  Where's this LED that lights up?  Any other useful markings on this PSU?

If you're not sure what you're doing, please leave well alone.  It will kill you, or someone else.

[guidoilieff]

What ground "output"??  That third terminal is for connecting the earth connection from your mains (and if you have a metal enclosure, it should go to a stud or bolt attached to the enclosure with a toothed washer - the mains connection attaches to the same place).

How do you know "positive and negative work" if you've not plugged it in?  Where's this LED that lights up?  Any other useful markings on this PSU?

If you're not sure what you're doing, please leave well alone.  It will kill you, or someone else.

Here I go again. Heres the actual power supply, you can see the LED at the bottom right next to the V adjust.




Here is the idea: Powering a TDA2040



I connected it to 220v, I already tried to make it work.  Tested it with the DMM and tried to light up a working LED
The green cable is connected to the ground "output" I was talking about.

In the pcb at the right side is resistance load, V+, ground and V- right?

heres the original project I made http://www.generalguitargadgets.com/pdf/ggg_20x0_amp.pdf

and here is an updated top view

[guidoilieff]

This is just a prototype btw

[Transmogrifox]

bluebunny is correct.  The "ground" connection is part of the AC mains input.  This should connect back to your electrical system ground through a 3rd prong in the electrical cord to keep the chassis of this thing safe in the event of a failure in the insulation system.  Most likely there is not an electrical connection between DC outputs and the ground lug, so what you are trying to do is not working because it's not designed to work that way.  .

If you want to get +/- and "ground" output, then you need to use both DC outputs connected in series (like stacking a pair of batteries).  Connect + output1 to - output2.  The connection between + and - of the 2 outputs is the kind of ground reference you're thinking about. 

One warning is if they DO have the negative terminals connected to chassis ground then you're stuck and you can't use it this way.  The consequence of doing it the way I stated if they have internally grounded the DC outputs is you will short one of them and potentially damage your power supply if they haven't implemented a good overload/short protection circuit.

Then the unconnected + and - outputs are your system positive and negative voltages.

Now if you need your grounded output to be earth-grounded then you can connect your "signal ground" reference to chassis.  This would be the equivalent of what a ground-lift switch does.  It would be like putting a switch between signal ground and mains earth connection allowing you to disconnect ground if the system was already grounded somewhere else.

[bluebunny]

Do you know what the +V and -V terminals are supposed to be giving you?  Are they all the same?  Do you have any documentation for this thing?  I'm still concerned for your safety, and I'm also concerned it's not actually a bipolar power supply - in which case it's not right for your application.

[guidoilieff]

O my god thats not a split poder supply??? I must looked like an asshole.

Didnt understand the ground connection thing, but thats fine.

[guidoilieff]

Hoooo, I get it. Its for that 3rd connector, we dont use that in Argentina. Sorry for wasting your time everybody.


So, can you split a DC supply with just diodes and capacitors?

I want that amp to work! Why im being so dumb with this thing??? I have that  tda2040 circuit  laying arround for almost 2 years! sorry if i sound frustrated

[PRR]

> I connected it to 220v, .... tried to light up a working LED

And?? Did it light? Not-light? Blow-up or smell bad?

> Heres the actual power supply

"Here" is actually on your desk. We can't examine it.

What voltage is it made to put out?? This information should be on a label I can not see in your image. (The V-adj probably trims 22V-26V, some very limited range around nominal voltage.)

What is the maker and model number? We may be able to figure something from that information. They probably use the SAME chassis and screws for different designs from 3V to 48V, we need the specific part number.

This is almost surely Single Supply.

> the original project I made

This is wired for dual supply.

> can you split a DC supply with just diodes and capacitors?

For very small power (preamps, pedals) you can "split" with resistors and caps, yes.

For a POWER amp, the splitter would have to be far bigger and hotter than the amplifier.

[guidoilieff]

> I connected it to 220v, .... tried to light up a working LED

And?? Did it light? Not-light? Blow-up or smell bad?

> Heres the actual power supply

"Here" is actually on your desk. We can't examine it.

What voltage is it made to put out?? This information should be on a label I can not see in your image. (The V-adj probably trims 22V-26V, some very limited range around nominal voltage.)

What is the maker and model number? We may be able to figure something from that information. They probably use the SAME chassis and screws for different designs from 3V to 48V, we need the specific part number.

This is almost surely Single Supply.

> the original project I made

This is wired for dual supply.

> can you split a DC supply with just diodes and capacitors?

For very small power (preamps, pedals) you can "split" with resistors and caps, yes.

For a POWER amp, the splitter would have to be far bigger and hotter than the amplifier.

God only knows why I thought it was a split power supply.


I tried again approaching it like a single power supply and the led I hooked up did light up. Everything is fine with this thing it seems.

It has an output of 12DC volts 16amp with an input of  230AC volts 50Hz. The makers is KONNEN and I couldn't find a picture or a web page naming this brand.

The amp I made is for a dual power supply because I didn't knew what a dual power supply was or even that they existed.


Sooo... there is no way this thing can power this tda2030 in a "dual supply" way? I know there is a single supply version of this pcb but I want to learn something out of this mess I made.

Thanks for that tip at the end, Ill look up for that.

[PRR]

12V at 16 Amps ??

That will power the biggest car radios. 4 channels at 16W-20W each. So you find a good car radio with the AUX input (look for mini-jack on front), buffer a preamp to both channels of that jack, and find four 4-Ohm LOUD-speakers. Lot of speaker wires! Big sound. Especially with proper guitar speakers instead of the small full-range toy speakers in cars.

Or study Taylor's Tiny Giant which is a car-sound power chip and 20 Watts. He uses a regulator to drop a 19V laptop supply to the 12V level, you don't need that. This 12V 16A supply should feed 4 Tinys (on 4 speakers).

It's not really a good voltage/current ratio for any "simple" loudspeaker amplifier to use.

[guidoilieff]

12V at 16 Amps ??

That will power the biggest car radios. 4 channels at 16W-20W each. So you find a good car radio with the AUX input (look for mini-jack on front), buffer a preamp to both channels of that jack, and find four 4-Ohm LOUD-speakers. Lot of speaker wires! Big sound. Especially with proper guitar speakers instead of the small full-range toy speakers in cars.

Or study Taylor's Tiny Giant which is a car-sound power chip and 20 Watts. He uses a regulator to drop a 19V laptop supply to the 12V level, you don't need that. This 12V 16A supply should feed 4 Tinys (on 4 speakers).

It's not really a good voltage/current ratio for any "simple" loudspeaker amplifier to use.

I stood late at night yesterday researching the Taylor´s tiny giant.

What you mean is making four separate Taylor's amp with one speaker each, but with one common input. Is that right?

i allready made my own pcb, but cant find the IC on Argentina and I have no credit card... I'll try to find a replacement.

[Transmogrifox]

Unless those 470uF bulk caps are wired in series they're under-rated for 230 VAC operation. After the rectifier the bulk voltage will be somewhere around 300V on a 250V cap.  Maybe series/parallel is one of the differences between 230 version and 120 version.

Also I am doubtful it could sustain 16A for very long.  Usually those ratings are more of an absolute max it can deliver but doesn't make any statement about whether it's able to do that kind of load for more than a few minutes.

Good thing about audio amplifiers is the load profile is about right -- you aren't likely to tax a 200W amp at 200W continuously.  It is probably not frequent for an individual to be listening at maximum power with highly compressed (techno/electronic/big bass) music.  On the other hand, that is exactly why disco/dance clubs are so hard on amplifiers -- they operate them all night long at their maximum ratings.

[PRR]

> under-rated for 230 VAC operation. ...Maybe series/parallel is one of the differences between 230 version and 120 version.

Much stuff I see has a 115/230 switch. Caps ARE stacked. 115V is doubled, 230V isn't. A simple switch converts the rectifiers.

His board has the holes for a 115/230 switch, but no switch. Also marked "230V" (only). I assume they knew it was going to a 230V-only market, omitted switch, installed jumpers.

> doubtful it could sustain 16A for very long

Wise to consult the manual. Sometimes the top spec requires fan-blow.

However a builder struggling to collect parts for a 30W amp is unlikely to strain a 200W supply any time soon. The biggest 4-channel car radios won't pull over 130W at 12V. And as you say, speech/music isn't steady.

[Ice-9]

That PSU is for a  3 axis CNC machine, the V- and V+ would be used to power the stepper motor drivers. No reason why it can't be used for other stuff though.

[intripped]

isn't it a LED Driver?

[Ice-9]

isn't it a LED Driver?

?? no it is a cnc 3 axis power supply

[intripped]

i know nothing, really, but i've seen these type of power supplies used as LED drivers, that's why i asked
like here:
http://cmilighting.en.hisupplier.com/product-1497254-12V-Small-Volume-Output-Switching-power-supply-for-LED-Strip-light-transformer.html

[R.G.]

Actually, it's a super-common variant of a switching power supply that is optimized for driving LED strings. There are so many of these made that they're stamped out by the zillions, and have become the cheapest source of power for most things that will run on 12V. I'm looking at its nearly-identical brother in the frame of my 3d printer kit. They're available from ebay for about $20 each in the 16A and 20A output levels. The 20A versions use a solid cover, not perforated, and have an internal fan to force air through it.

The input is switched from a bridge rectifier for 220/240 operation to a doubler for 110/120 operation, into stacked first filter caps, as Paul noted.

Whenever you're confronted with an array of V+ and V- pins, get out your ohmmeter. My particular power supply has two V-, two V+. Ohmmeter says both V- and both V+ are common, they just gave you more screw terminals to connect.

These have become co-opted for lower-power stepper motor and servo supplies for low-end CNC machines because they are so very cost-efficient for getting 12V.

[Ice-9]

Well there you go, I never knew they were used also in led strings.

The 12v variants will be common in 3d printers which use 3 axis cnc but for larger hobby cnc machines to cut alloy then the better choice are the 48v versions which have the same layout and format.

The three outputs for V- and V+ are usually not separate outputs but are three terminals to the same output. This is so that each device connected has its own wires to power them rather than daisy chaining them together over one set of wires. That does not mean they are all common connected at the psu though so as RG said meter the terminals out first to check.

See above ... it is not possible to connect the outputs  +,-  in series to create 12v 24v 36v  outputs if they are connected in common at the psu end. This will short out the outputs.