HumLess PSU Revised

154

05:28:46

This type of regulation is designed when the circuit you're dealing with requires extreme regulation. Such a demanding system would be a preamplifier circuit or some types of VCO oscillators for instance where utmost stability is required to achieve best results. Bad regulation may introduce noise in the preamp stage which usually carries the distortion for futher amplification by the power stage. In oscillators it may cause the frequency to drift which is also an undesirable effect.

About the How? The left one uses a constant current source and some filtration to achieve the astonishing -127dB attenuation which will decrease a 1V ripple down to 500nV. The circuit on the right is a similar topology but instead of Constant Current Source, a bootstrap is used to achieve similar effect with the same dampening factor. I personally recommend the one on the left. The right one is very hard to tweak and requires these exact components to work properly while not having any dissimilarities in parameters to the other one. 

published 10 years ago

hurz

10 years ago

There is only one pitfall check this http://everycircuit.com/circuit/6225198001946624 and try the miller cap effect in your circuit with 495pF. The bodeplot have to be discussed with Igor.

GingerKing

10 years ago

Looks good. No one want to amplify ripples coming from the suppy. Why 100Hz? Here in the US we use 60Hz mains. Fully rectified it would be 120Hz. Should i be targeting one of those frequencies?

thebugger

10 years ago

I live in Europe and we use 50Hz. At 60Hz the one on the left (the one i recommend) will work exactly the same, but the one on the right will have less ripple rejection because it's very frequency specific.

thebugger

10 years ago

Hurz i don't get where the problem is and why you're referring to an oscillator. The bootstrap will not cause oscillations because an emmiter follower has a voltage gain of <1. Plus i too don't like that topology. I'd recommend the one on the left but I'm just reviewing the different available options.

jason9

10 years ago

You shouldn't even post the one on the right because after the diode bridge you will have a triangle wave which contains harmonics which will not get filtered out!

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.