Ok so just to actually finish up this post... Basically if I want to minimize voltage drop, it would be done through the transformer. I could either use an adj transformer, or a center tap transformer (to achieve a half voltage output from it).
Other than that, theres no other "tricks" other than using switching, which I basically do not think I will be implementing.
Pretty much. There are many different ways to "burn off" the extra voltage coming from the transformer but they all involve just that: converting the energy into some other form of energy that you can then get rid of. I learned this when making a 12VDC 1A regulated supply a couple of years back: all I had lying around was an 120V-18V transformer and I wanted to avoid having to put a freaking huge heatsink on the regulator. My choices were essentially A) put in some power diodes to drop the voltage (but the diodes then needed to dissipate the energy as heat), B) use resistors to drop the voltage (but then the resistors needed to dissipate the extra voltage as heat), C) put a heat sink on the regulator (and let it dissipate the heat), or D) use the proper transformer and not have to worry about it.
I went with option D in the end.
(I'm sure there are other options as you noted, like switchers--but I'm also grateful that the people on forums like this recognized that I wanted to design it mostly myself and I didn't stand a hope in hell of designing a good, safe, and reliable switcher by myself at that point. Honestly I probably still don't).
Since you guys seem willing to take this just a bit OT, you can help me finish basically the other design aspect I should consider; whether or not I want this to be a bi-polar supply. First of all, I am under the impression that a bi-polar supplys positive voltage will equal to its negative voltage, they are not separately adjustable, is this true? Well, if I make this a dual supply (2 seperate uni-polar power supplies in one case), then I dont really need a bi-polar supply, right? Or would it still be useful to have a dual bi-polar supply in some cases?
So if you can just help me with that aspect, pretty much all of the questions I have will be in a separate post and will probably be after I started building it.
Thanks everyone!
Depends. You would need a dual supply for some analog circuitry but for digital stuff you should be fine in most cases with a single supply.
You could always design two supplies into one case using a common ground. One would be negative and the other positive relative to the ground. Then you could have either a single positive supply, or a single negative supply, or a dual supply, depending on the project.
But I'd start with building a decent single supply. Concentrate on making it work well, and on making it safe. You'll learn a lot doing this and can then apply that knowledge to the next one you build.
One thing I like to do with mine is put an LED between the rectifier and regulator to bleed off the filter caps when the thing is powered down. It's not usually necessary as an indicator (though it can be a cool one) since I usually use a lighted switch on the front panel, so I like to use a super-bright blue LED for this bleeder LED and just mount it somewhere inside the case. Then I get a nice blue glow from inside the thing when it's turned off, which fades out slowly after the device is switched off as it bleeds off the caps.
Cheers and good luck,
Torben