Accurate voltage regulation
 

Hello people,

I am going to build a power supply to power some guitar effects up.
The voltages that I am going to need are:

• 6x9V,0.5A
• 2x9 to 30V,1.5A

So I need 6 fixed supplies, and two that I will be able to alter depending on my needs. Note that I don't need the adjustment to be controlled easily, without opening the chassis etc. No external pots or switches needed, to be accurate.

I was leaning towards using LM317 voltage regulators, with which I am familiar. Actually I have designed the power supply based on LM317's (and LM350's for the variable supplies), but here I am seeking for a better alternative.

So, I have come across some transistor regulators appearing to have better noise specs than ordinary LM317 designs (how about ripple rejection?). I am mainly referring to this site, which should be known to many people in here, I suppose: Simple Voltage Regulators Part 1: Noise - [English]
But I am not familiar with this circuitry, and it seems to me that using zener diodes with fixed reverse voltage characteristics does not leave much room for flexibility.

So, should anyone be able to explain to me how to modify these circuits to produce 9V,0.5A outputs or even better to turn them into variable regulators, I would be glad to know.

Is there really any cheap and simple circuit out there to beat the ordinary LM317 design? That could be the thread's title in the first place, actually.

For 9V use L(M)7809 for positive polarity and L(M)7909 for negative polarity.
And preregulator for those chips are as LM317, LM337 .
.

I am sorry but I did not understand! You mean to use L7809 exclusively for the 9V supplies or to use LM317 first and after that the L7809?

Are L(M)7809 considered to be any better than LM317?

First use LM317 as a preregulator, L(M)7809 as a main regulator.
For negative polarity is the same, if needed.

I need only positive polarity, thanks!
And what about input and output caps for each regulator?

well a transformer that puts out 12v AC at 1A and 24v AC at 3 A would be good , you can use a couple lm7809 regs for the 2x9v DC from the 12v AC tap and a LM317 or lm338 for the 9v -30v DC using the pot on the adjust leg of the reg off the 24v AC tap .... Using a TX with 2 seperste taps will give you some isolation between the 9v dc and 30v dc supplies ......

Cheers

PS if you want to go super simple and cheap you could use a single 12v DC Xformer and rectify the 12v ac to 17v dc and regulate down to 9v dc and then use a voltage doubler off the 12v ac to get your 34v DC and regulate down to 30 v and adjust with a trim pot on the adjust leg of the regulator ......

Please tell me your opinion on this: I was planning to use LM350T's for the 1.5A supplies - do you think it is better to do so, or is it better to use a LM317 stage in addition with a transistor or mosfet to provide the extra current? I know LM317 is specified at 1.5A load, but I don't want to push it that far.