I have a question about running an lm317 supply with a common mode choke upstream.
Scenario A would have the choke between the secondary of the transformer and the diodes
Scenario B has the choke after the diodes before the 1st smoothing cap basically forming an LC filter.
The diodes are double rectifier type.
Which secneario is more benefitial and does the psu impedence seen by the 317 change between scenario A and B?
Scenario A would have the choke between the secondary of the transformer and the diodes
Scenario B has the choke after the diodes before the 1st smoothing cap basically forming an LC filter.
The diodes are double rectifier type.
Which secneario is more benefitial and does the psu impedence seen by the 317 change between scenario A and B?
The best case is with the filter ay the primary of the trafo because it difficults EMI to pass to the secondary via pri to sec capacitance.
Output impedance is a function of the gain of the error amplifier in the LM317 and the transconductance of the pass device. If using LM317 would advise looking at Elvee's "De-Noiser" -- a remarkable idea which both lowers the noise and output impedance of an LM317 regulated supply with only a few components.
I meant the overall impedence of psu before the 317, not the regulator's output impedance.
Denoiser is a wonderful circuit btw. Ive breadboarded it before (thumbs up)
Denoiser is a wonderful circuit btw. Ive breadboarded it before (thumbs up)