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