Felipe La RottaThis is a electronics-focused project (again!). If you don’t like electronics, please feel free to browse the other projects.
__________________________________________________________________________________________________
.
Purpose
.
Everyone who plays with electronics needs some way to power his/her creations. Of coarse, if you work in NASA the money is not a problem. But for the average-DIY-Joe on a Latin American Country, getting decent equipment tends to be very hard…
Or Perhaps Not!
Stop using wall warts and that crap, the answer is right in front of you, and you don’t need to be an engineer to build it. Do you hear the fan humming in the back of your computer? Yes! the answer is a Computer’s PSU!
ATX PSU with cover removed – picture by Mboverload
Computer PSUs are great: they provide a wide voltage range (12, 5, 3, -5, -12) and nice amperage (12V 15A, 5V 22A).
__________________________________________________________________________________________________
.
Turning On AT or ATX PSUs
.
There are two common types of PC power supply: AT and ATX. The AT ones are old as hell, they are easy to identify looking for a huge switch attached to them.
The ATX-types are not equiped with switches. To power up them you should find the green wire, and short it with any black (0V) wire. I’ve made a small diagram to help you
Please note that some ATX PSU’s will not turn on if no load is attached to them.
__________________________________________________________________________________________________
.
My project
.
Ok, this is my PSU. As an Industrial Design Student, I was obligated to make a decent Casing and Interface for my project: You know, grey metal boxes are not good for Ergonomics and Usability. The ugly silver pot knob was replaced by a black one, some days after the taking the pictures.
At the upper-right corner you can see the ATX PSU printed circuit board. The transformer and the other PCB shown in the picture are a very simple LM317 variable supply.
You can get your PSU (new or used) on any computer maintenance store. If you don’t have anyone around, there is always a computer to cannibalize near you
2011 EDIT: Look at the comments section below for more information (English and Spanish)
[...] La Rotta from Engallamientos de La Rotta has built a number of cool DIY projects, this DIY Bench Power Supply is one of my favorites. Everyone who is tinkers with electronics will eventually need to progress [...]
[...] La Rotta from Engallamientos de La Rotta has built a number of cool DIY projects, this DIY Bench Power Supply is one of my favorites. Everyone who is tinkers with electronics will eventually need to progress [...]
The schematic for the LM317 supply specifies Vin > 28V ; does this still work with a 12v supply?
Hello Scott!
Not necessarily, it depends on what output you need
Input voltage must be at least 3.7 Volts more than your maximum desired output voltage AND voltage difference between input and output must not exceed 40 volts.
I wanted 1,5 to 30V, so I used a separate 35V transformer/rectifier.
For more info about the LM317, look this page
http://www.k7mem.150m.com/Electronic_Notebook/power_supplies/lm317.html
My computer PSU is only used for +12, +5, -5 and -12 fixed outputs
Awesome ! Very neat case design !!
Why don’t you combine your 12, 5, 3, -5, -12 voltages instead of the LM317 ?
It would be definitely more efficient and less heavy… But yes… you can’t get the same range and precision.
Bye !!
Hello Dainaccio!
Thank you very much for your commentary! There is a reason for that: The +12 and +5 lines provide 15 and 22A (great!) but the -5 and -12 lines only provide 0,5 A. Combining them with the +12 or +5 lines will trash the awesome amperage. I mean, under any significant load the protection circuit will kick in and PSU will turn off.
Hi, Felipe!
A very interesting and very well-done project. If I’m not mistaken, that’s a Black & Decker case, yes? Any idea what specific tool it was for?
I’ve started down this road with a few cordless-drill cases, (Dewalt, Makita,) but never finished one yet. In my *ahem* case I was planning to construct a Windows PC with a small mini-ATX motherboard. I do a little bit of computer “house call” work and I often find it handy to be able to analyze and/or repair a customer’s hard drive without having to boot from it. Hence the desire for a cheap, portable, rugged desktop-PC box. Now that I’ve seen your excellent work, maybe I’ll go and finish one!
Hey MacMarty! Thank you so much by your comments!! I’m very glad that you liked my work.
Your are right, it’s a Black & Decker RTX. My ex-girlfriend gave me a better case, so I used the old one for this project.
The tool is still working great 4 years later, you can check it here:
http://www.google.com.co/images?hl=es&q=Black%20%26%20Decker%20Rtx-1&um=1&ie=UTF-8&source=og&sa=N&tab=wi&biw=1280&bih=687
By the way, I’ve made a computer case just like the one you are describing! I’ll search for the pictures of the construction on my old CD’s, so you can get more inspiration for your project.
Check out the blog on a few hours!
The new post is ready, check the main page!
http://www.engallamientos.wordpress.com
[...] La Rotta from Engallamientos de La Rotta has built a number of cool DIY projects, this DIY Bench Power Supply is one of my favorites. Everyone who is tinkers with electronics will eventually need to progress [...]
[...] Top Power! Everyone know that powering your gadgets can be a pain. But [Felipe La Rotta] came up with a cool idea for a bench top power supply. He used the power supply for a desktop [...]
Hey Felipe,
Este “engallamiento” esta muy bueno, Felicitaciones!!!
Justamente esta semana se me había ocurrido hacer los mismo ya que estoy próximo a comprar una fuente nueva y quiero hacer algunos proyectos con leds RGB, veremos que pasa ya que mis conocimientos en electrónica son muy básicos pero este post es una buena guía y sobre todo me confirma que si es un proyecto viable.
No me queda muy claro el tema del transformador LM317 (por que y como se debe usar)… mi ingles no es el mejor…
Apropósito, tienes algún proyecto interesante con Led RGB??
Saludos.
SR camilo saludos mi nombre es anibal la razon de este mensaje es para ofreserle revistas de electronica en espanol son de mexico tengo como unas 40 son buenas bastantes proyectos basicos si le interesan mi e mail raguilar8@optonline.net mi tel.203-604-5493 saludes…..
Que mas Camilo!!
Antes que nada muchas gracias por visitar mi blog
Bueno como usted sabe la fuente provee una gama de voltajes (+12 +5 3 0 -5 -12). Pero lo mas bueno no son los voltios sino el amperaje: la linea de 12 provee 15 amperios, y la de 5 dá 22 (Vaya y trate de igualar esos numeros con un transformador normal, y sería severo ladrillo.)
Ahora bien, digamos que no quiero 12 voltios sino 24. Para eso la fuente tiene otro truco bajo la manga: Si uno junta los cables (digamos el +5 con el -5) el voltaje resultante se combina: = 10V. Lo mismo pasa con las lineas +12 y -12.
PEEEEROOOO la cagada es que ahi perdemos el beneficio del amperaje: La linea de -12 voltios solo dá medio amperio. Eso quiere decir que cuando la combine con la linea de +12, si listo, va a obtener los 24 voltios que quería, pero ese mediocre medio amperio no le sirve para mover nada decente. Apenas intente conectar algo mas grande la fuente va a entrar en modo de protección y se apagará (como si estuviera en corto).
No intente conectar las lineas +5 y +12, eso tambien va a disparar la proteccion.
Bueno por todo eso me vi obligado a añadir un transformador por aparte(el verde que ve dentro de la caja). Dá como 40 voltios AC, no recuerdo bien, y unos cuantos amperios.
Como la corriente AC no sirve para los proyectos, añadi unos diodos y condensadores para rectificarla y convertirla a DC (en el blog explico como hacer eso).
Ahora quiero que esos voltios varien (de 0 a 30) dependiendo de cuanto yo gire un potenciometro. Ahi es cuando entra el LM317, un regulador de voltaje variable.
Lease el post de esta vieja, es buenisimo
http://www.taringa.net/posts/ebooks-tutoriales/2553964/Electronica_-Fuente-de-Poder-de-0-a-30-Voltios-LM317T.html
El LM317 aguanta un amperio y medio, aunque haciendole unas modificiaciones que recomendó un visitante de este blog podría soportar muchisimos mas (LM317 with passing transistor).
Pero usted no necesita tanto voltaje y amperaje. Con la fuente ATX que ya tiene y un LM317 conectado entre 0 y +12 tendra una fuentecita variable muy bacana para cualquier proyecto que quiera hacer.
Para controlar el brillo de sus LED RGB es indispensable que lea sobre algo llamado PWM (Pulse Width Modulation). En google hay miles de circuitos hechos a punta de integrados 555, que le permitiran controlar el brillo de sus LED. Claro que la gente pro lo hace con microcontroladores y jodas mas complicadas, pero bueno eso usted lo verá mas adelante. Yo vere! cuando lo aprenda me enseña, porque yo soy negado para eso.
Si necesita cualquier otra cosa solo aviseme!
Felipe muy bueno este proyecto precisamente tengo la computadora que tiene el power suppply esta bueniiiiiiisimo me encanta felicitaciones y siga para adelante saludes……..
this is a very good job.surport all of you.