How to Make a Low-power Power Supply Unit From Discarded DVD Player

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Introduction: How to Make a Low-power Power Supply Unit From Discarded DVD Player

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Have had enough of taping together batteries or making tagliatelli of wires to provide some volts for your electronic project? Yes you have !

Instead of buying a new PSU (power supply unit) why not use a power circuit board from discarded A/V equipment or some other home appliance. Many audiovisual devices in your home have built-in power circuit boards providing juice for the inner electronics operating at 3.3V, 5V, 10V, 12V et cetera. Although they often provide low current they could be well suited for your electronic projects such as LED lights, small motors, and other low power stuff.

I hardly throw away electronic appliances so I had a look in my pile of A/V equipment for what might be suitable as DIY power supply. Some other equipment I came across even had 1.2V, 7.5V, 9V, and 15V too, again, all at once. I chose to use a low-end DVD player having a nice little power board providing me 3.3, 5 and 12 Volts.

Here is how I did the whole thing.

Tools needed:

· the obvious screwdrivers, perhaps also Torx
· screws, brackets, encasing of any kind of your liking
· multimeter
· cutter and pliers
· soldering iron
· some wires and other small conductors to serve as bridge, manifold or DIY connections
· a discarded appliance like DVD player, VCR, CD player or anything you'd like to try out for donor

NOTE of CAUTION:decide for yourself what materials and components you are going to use whilst being realistic and considerate of risks these kind of project may bring. Always keep safety in consideration, especially when other people than yourself use your creation or are near it.

Step 1: Empty, Unplug and Open the Casing

Let's presume you selected a discarded DVD player for this project, as I did too.

Check to make sure there are no DVDs or CDs left in the tray. Switch it on, then unplug it from the power outlet. This way you discharge capacitors and prevent a nasty bite in the fingers. At any and all case, don’t touch the electronic components or wires unless you’re absolutely sure all components have discharged.

So now, unscrew the casing (you probably couldn’t wait and already did it)

Take a picture of the inside for your reference. Locate the power PCB (‘printed circuit board’). Typically this is a separate PCB at which the power cord leads to. I marked it with an ellipse, see photo. Some power cords use connectors, others are soldered. If there is no separate power PCB, yer unlucky. Or, find a bigger casing to accomodate the entire circuitboard, but you might then as well keep the entire DVD device and have the wires coming out of the DVD tray slot ;-)

Note: the photos in steps 1 and 2 of this Instructable are from an HD recorder, but I used a DVD player. The principle and work approaches are the same. I built this project some time before I made this Instructable therefore I couldn't make photos from the original DVD player anymore.

Step 2: Disconnect and Unscrew

Disconnect the small wires to and from the PCB and other components such as the DVD tray, front display et cetera. Usually they are attached with flatcable connectors. Keep the screws for later or other use. Some connectors you can unplug on one end by using a small screwdriver and carefully pry between the 2 tiny plastic parts of the conncector or pull with modest sideways rocking, not tilting the connector. The photo shows I pull by the wires, which is not the Official Best of All Methods, but gripping the plastic connector with my fingers seldomly worked for me .
To make removal of the PCB board a little easier I removed all cables, including the ones attached to the PCB itself. Just make sure you understand or remember what wiring is relevant for you.
And don't just yank it out. Instead, cut the wires if they are soldered but make sure to leave the wires on the power PCB end.

Unscrew the power PCB and try to keep the power cord attached when it is soldered. You’ll need it powered, not?

Most often, the power PCB has voltages printed in tiny letters following the order of the tiny wires. Write them down, they are your future power leads. Note that many power supplies also have MINUS volt connections, meaning that combined with GND (ground), it gives negative volt. If you reverse polarity, you’ll have PLUS. Or, you could make a combination of, say, -12V and +12V and so have 24 Volts, but I am not sure if that will be a steady supply since you have no GND then.

Step 3: Encase It and Present Power

Find a non-conducting encasing which is sturdy enough for handling and has the right properties and dimensions to fit, mount and screw the PCB in AND to put in some additional wiring for your DIY connectors or wiring coming out. I used a wooden box holding a long gone mini bottle of booz.

You may want to have some room in your encasing, perhaps you want to add another PCB or even a dissassembled power adaptor from phone, laptop or whatelse (I'll make an Instructable of that when I get to it)

Be creative and resourceful to mount the PCB in the case and have the power cord neatly going out. Beware to not screw through the bottom or sides because you want to have the PCB isolated.

Tip: if you drill hole in Plexiglas, PVC or PET, you'll notice that often the material melts due to the friction and wraps around your drill bit. The trick is to drill a short while (say 2 seconds) then wait for the molten plastic to harden, then continue, et cetera.

Think of a way you like to have your power presented on the outside. I chose to use a breadboard (often used for Arduino controller boards) on a transparent top over the box.

Make it so !

Qwertypat, february 3rd, 2016

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16 Comments

This is a great article. It would be nice to see how to hook this up to a few LEDS for welding in dark areas. Most of my plastic flashlights eventually melt due to hi hear while welding. I need to make my own flashlight that will use the replaceable welding shields for a longer life.

1 reply

Hi Merkeligur, thanks.Intesting idea you have, I think.

You mean welding like MIG/MAG and electric arc welding? That creates a lot of heat indeed and I have no experience how to prevent overheating a near/close lightsource. Perhaps you can use a piece of a glass from heat resistant glass, like an oven dish or maybe even from a car's halogen headlight and use it as a shield?

cheers, qwertypat

the capacitors in those old devices are dried out and out of spec. especially if they were made in china

1 reply

Hi Mike, yes indeed, many modern devices have components of questionable quality and it doesn't get better over time. The DVD player I used had a mechanical defect and the power circuit worked still fine (no clue how long it lasts though)

Neverthless, re-using good parts and components is a way to give it a second life with fun in the first place. ;-)

cheers, qp

You can get free power supplies from abandoned PC computers.
People are happy to give away their old CPUs, and they can be a great source of parts (Power supplies, fans, etc.)

1 reply

Hi Mark, thanks, yes me too have a pile of them. They are stable, already encased and abundant. Yet I was often in need for different voltages like 1.5, 2, 3, 7, 9, 15 volts for powering components like sensors, IR and Laser LEDs, tiny electromotors etc. ATX and BTX PSU's don't offer that, as far as I know.

cheers

Without a case ground or proper ventilation, this is bad practice and could be very dangerous.

3 replies

Hi Robert, I appreciate what you say -DIY electronic often can be dangerous.

With regards to Ground - the regarding DVD player, and most players, has no earth over the 2 wire AC powercord. The Ground in the device is 'local' and called a Floating Ground. The secondary circuitry of the power PCB is low voltage and is not directly connected to the high voltage 230AV, merely through a transformer. Earthed ground is not an essential in this setup.

True ground ('earth') is rarely used in home A/V electronics.

With regards to ventilation: the DVD player it came out was a small sized case with no ventilation at all. Also consider power adaptors 230V /5v/ 9V /14, they are crammed in plastic with no earth ground, no ventilation and higher current than the power PCB I used. Of course, power adaptors use plastics that can withstand heat, yes.

Nevertheless, thanks for you reaction and consideration !

If you work right with electronics, It isn't SO dangerous...

There is probably a bigger chance of dying by getting hit by a car, Than getting shocked and dying while tinkering with electronics when working with appropriate safety gear (Sorry for that example, But you know what I mean, Everything in life is dangerous...)

tx for the relativating reply Yonatan, and yes statistics indeed give a view on how life has dangers for us. And also I think we all agree that we should do our best to lower risks when we have the reason, experience or expertise to do so.

cheers

Thanks for posting this. Motivational.

Without a case ground or proper ventilation, this is bad practice and could be very dangerous.

hello kodiak, because the photos in Step 1 and 2 are from a a Harddisk recorder (HD recorder) as I mentioned. This has both a DVD player as well as a harddisk. Also as mentioned, I used a regular DVD player and some time before I made this Instructable therefore I couldn't make photos from the original DVD player anymore.

regards

qp

Hey Hank, great Instructable you have and cool to see similar minded people doing the right thing !