ATX Bench power supply, ideas and suggestions wanted

[Ludvig82]

Ok, to be honest i could do with a step down converter, So i get 12v and under. What would you reccomend to use then?

Could this do the job?
http://www.ebay.com/itm/5A-Adjustable-CC-CV-Display-Step-Down-charge-Module-LED-Panel-Voltmeter-Ammeter-/381374424481?hash=item58cbafe5a1:g:wfQAAOSwKrhVW~45

I could also be brave and try to solder my own board with a kit like this: http://www.ebay.com/itm/1-x-LM338K-3A-Adjustable-Step-Down-Power-Supply-Module-DIY-Kits-Components-SY-/281830066652?hash=item419e6189dc:g:V4AAAOSwo0JWIPP3

[Paul Price]

If you want a supply with an output of 12V or less, the ATX supply doesn't look as promising. A buck step-down converter requires that the input voltage be several volts above the output voltage..same is true for the LM317 if you go linear with a big heatsink, so you would be limited to a regulated output voltage high limit around 9V or so at full output current.

In this case I would acquire(possibly in many cases for free) a laptop power supply, many of these can supply 3 to 4.5 amps at 18 to 21V, depending on the manufacturer. In this case a LM317 regulator on a sizable heatsink would make a nice bench supply with a decent output voltage capability from about 1.2V to about 15 Volts or more depending on output current. Just don't choose a wooden case for the supply if you don't want to burn down the house.

[Ludvig82]

If you want a supply with an output of 12V or less, the ATX supply doesn't look as promising. A buck step-down converter requires that the input voltage be several volts above the output voltage..same is true for the LM317 if you go linear with a big heatsink, so you would be limited to a regulated output voltage high limit around 9V or so at full output current.

In this case I would acquire(possibly in many cases for free) a laptop power supply, many of these can supply 3 to 4.5 amps at 18 to 21V, depending on the manufacturer. In this case a LM317 regulator on a sizable heatsink would make a nice bench supply with a decent output voltage capability from about 1.2V to about 15 Volts or more depending on output current. Just don't choose a wooden case for the supply if you don't want to burn down the house.

Ok, i have several laptop power bricks lying around. Never throw those away Maybe that is a better idea then, since it is variable, i can use it for all the purposes that the atx PSU would give (3.3v, 5v and 12v.) With the heatsink i understand that wood would be a nogo, would it output alot of heat? I have several hetasinks from different computer pars lying around, never throw them away either

With the choice of several power bricks, should i use the one that got highest amp output?

[Paul Price]

The higher current bricks will be more rugged and run cooler. If you want a nice adjustable supply then buy a simple LM317 module to give you really clean output..heatsink required.

http://www.ebay.com/itm/5A-Adjustable-CC-CV-Display-Step-Down-charge-Module-LED-Panel-Voltmeter-Ammeter-/381374424481?hash=item58cbafe5a1:g:wfQAAOSwKrhVW~45

I haven't any experience with this module, I donno, never dated this girl, but might be worth shaking a stick at.

This module, like all the other adjustable modules will have a small trimpot mounted on their PCB. If you wish to use that fancy knob of yours be sure to to try to keep leads short as possible to the module you are attempting to control with pots on the front panel.

Some soldering required.

[Ludvig82]

Yeah, looked at several of these now, and i guess i can change to a bigger heat sink if i want to

For the sake of making it a bit easier in myself, i looked at some with potmeters with axle. I'll link to some of them, and would really appreciate if you could give me your 5 cents in them

http://www.ebay.com/itm/DC-AC-LM317-Adjustable-Voltage-Regulator-Step-down-Power-Supply-Module-LED-Meter-/391251584891?hash=item5b1869677b:g:kEcAAOSwMmBV7CPs
http://www.ebay.com/itm/New-LED-Display-LM317-Adjustable-Voltage-Regulator-Step-down-module-AC-DC-Hot-/252108685154?hash=item3ab2d93f62:g:wwYAAOSwiLdWCmdt
http://www.ebay.com/itm/LED-display-LM317-Adjustable-Voltage-Regulator-Step-down-module-updated-lastly-/291523096161?hash=item43e0216e61:g:z~gAAOSwu4BVsucC

[Paul Price]

The modules you've presented do not have more than one protruding control..means no control of current.

The one I presented doesn't have external pots but could be adapted to front panel controls easily and you have voltage and current metering.

Some soldering in any case.
To play with anything electronic you will need a soldering station of some type, might as well start to use one to assemble your power supply.

[Ludvig82]

OK, easiest way to adapt them is to get external pots then?

Sent fra min London via Tapatalk

[Paul Price]

Yeah, but pots are not as easy or cheap to buy or as nice to me as my own digital controls with a MCU, but you might not be ready for that challenge yet.

But you can find them cheap enough on ebay et al.

[Ludvig82]

Sounds interesting with the digital controls, but I think it may be for later. What do I have to look for when buying pots then?

Sent fra min London via Tapatalk

[Paul Price]

Very important: Match the resistance value  and taper (linear in this case) to the ones on the module, and oh..make sure it fits your knob.
In some cases, to be properly shafted, some sawing required and someway to drill a hole for the shaft.

 Look for ones that are sealed against dust, and wirewound pots might be troublesome with your module's circuitry, while some 10-turn pots might be a fancy option for high resolution setting of output voltage.

[MarkF]

MarkF: Good reasons not to just build a simple LM317 power supply are:
(1) You wouldn't learn much about electronics, or op-amps or current sensors or boost supplies or MCU programming, etc.
(2) You would have to pay for all the parts.
(3) You would need a very large heatsink and a fan.
      For instance, if you wanted to output 1.6 Amps at 1.6 Volts for an electrolysis experiment, the LM317 would be dissipating around      1.6A*24..say something about at least 40 watts of power. Makes your power supply a nice room space heater.

And what do you learn from plugging in a pre-made module?  NOTHING.
Yet a few posts later you suggest getting a LM317 and doing almost the exact thing that I have!

I think i got a shopping list put together now. Hopefully this will be a fun project
. . . . .

The DC-DC buck module I pointed out has Constant Voltage select, Constant Current select and voltage, current and power measurement via the buttons.  Everything that all your modules together provide.  I saw a video with the same or similar module.  Please do a little more research before deciding.
http://www.aliexpress.com/item/B3008-precision-CNC-DC-DC-constant-voltage-constant-current-buck-LED-driver-modules-solar-charging/1550355670.html

Here is a second video by the same gentleman:

[jmegar324]

Any specific applications you are using it for? It may help people recommend something better suited

[Cliff Matthews]

These SMPS bench threads go on.. On that $10 kit (sans brick or transformer), the most needed upgrade seems to be fine adjustment. Since the controls are ergonomically too close together, I'd short jumper them to a front panel and parallel-wire the wipers to another 20k pot with 47k resistors linking the outside contacts. AFAIK, this should add about 4% (+-) adjustment without PCB changes. Perhaps that part was what was missing? Or maybe metering.. like this: http://www.ebay.com/itm/DC-100V-10A-Voltmeter-Ammeter-Blue-Red-LED-Dual-Digital-Volt-Amp-Meter-Gauge-/131577787046?hash=item1ea2a5b2a6:g:lFcAAOSwMmBVzF8~

Once again, don't cook your projects or feed them with dirty power, check the link http://www.ebay.com/sch/i.html?_nkw=Continuously+Adjustable+DC+Regulated+Power+Supply+DIY+Kit
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