noisless positive voltage regulators info

[nikifena]

Hi again
I search voltage regulators with less noise. When I test 78xx regulators with lm317. I see that lm317 are near 4-5 times noiseless.

I try to find anothner good and cheep regulators but I can't find anything.
Actually I search up to 1 A current and 3 terminal regulators (better is with 2 resistor configuation).

Thanks .

 

[Ave_Rapina]

You need to find an good regulator that haves a good factor of rejection of ondulation.
For example
Fr0 =80db see datasheet

Avipp = 10^(80/20)*Avopp
Avopp is the ripple desired in the output of the regulator.

Avimin = Vreg+2.5V usualy

An good regulator can give an more stable output with an more elevated ripple value in the input

 

[polymath]

What noise level are you looking for?
Why?
Can you filter supply?
What output voltage & what current?

Polymath

 

[nikifena]

I look better voltage regulator
something like this

An good regulator can give an more stable output with an more elevated ripple value in the input

I like to make quality power supply
I can filter with some capacitors (1000-2200uF) and like 9v output voltage with max current 1A, and with less elements, and better than lm317

Thanks

 

[Ave_Rapina]

You shoul calculate the correct caoacitor by this formula
C = I * Λt/ΛV Λt = 1/(2*f) if the rectifier is complete wave or Λt = 1/f for half wave

Λv is te ripple tension that you calculate in the entrance and is calculated based the Fr0 of the regulator and the maximum ripple in the output of the regulator
This information is mentioned up in my replie

Regards