Variable power supply

How much current do you require? Do you need current limiting? Do you want a linear or switching PSU?

 

Are you going to use it for your electronic projects? You will need current limit.

 

If your new in electronics. Go for analog variable power supply project. It s simpler but bulky.

 

Most (many) Lab Power Supplies are 0-30V and 0-3A. Here and here are shematic diagram examples that look like they'll work reliably.
For testing anything higher powered than a simple car radio you'll need a dedicated 13.8V 10-50A power supply though.

 

I actually just made my first power supply! Here's what I found:

I think you could make this work for up to 30V. If you have wall adapters laying around then you can use the LM317 voltage regulator (advertised to work up to 37V):

http://www.instructables.com/id/How-to-Build-a-Bench-Top-Power-Supply/

I can't find the link but someone out there hooked up a digital readout display to it that only costs 10 dollars !

looks like 30V is possible with almost the same exact circuit above:
http://www.electronickits.com/kit/complete/powe/ck402.htm

here is a cool kit from Jameco with negative and positive supplies with the use of a transformer if you don't have wall bricks. it's only 0-15V but you can probably use their schematic (included in link) and modify it to your purposes. Also, the video explains pretty well how it works):

http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_20626_-1

afrotechmods who has the greatest videos on youtube explains the voltage regulator here:


sorry to dump all these links on you but i just went through this myself!

 

shoot, looks like the DRO I was talking about works up to 20V but it's supposed to be real accurate

http://www.instructables.com/id/THE-EXTREMELY-SIMPLE-DIGITAL-DC-DC-POWER-SUPPLY/

 

good to know. I like the videos too! i love the internet...and foreign accents...

edit: the video is a little advanced! more studying for us beginners

 

haha human accent