Super Regulator

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jan.didden

jan.didden

AX tech editor
Joined 2002
linearaudio.net
Paid Member
HiFiNutNut said:
Here is a question.

We understand that there should be no low ESR caps at the load. Let us assume that the load has 5 x 22uF medium to high ESR low ESL electrolytic caps from a power plane to a ground plane for the purpose of local low inductance path for the power supply. The 22uF caps would cause no problems. But the power plane and ground plane would have a parallel plate capacitance from 30pF to 100pF, depending on the PCB power and ground plane sizes. Would this parallel plate capacitance cause problems to the SR?

I don't have any ideas about the "ESR" of the power and ground plane capacitance so I don't know the answer.
Click to expand...

Good thinking. Personally, I don't think it would be a problem but I haven't investigated it. First, the value is most probably too low to cause issues, and secondly there is some 'isolating' inductance between the SR and the load. The problem with too low ESR is anyway only for caps directly at the SR.

Jan
 
stormsonic

stormsonic

Member
Joined 2008
HiFiNutNut said:
Here is a question.

We understand that there should be no low ESR caps at the load. Let us assume that the load has 5 x 22uF medium to high ESR low ESL electrolytic caps from a power plane to a ground plane for the purpose of local low inductance path for the power supply. The 22uF caps would cause no problems. But the power plane and ground plane would have a parallel plate capacitance from 30pF to 100pF, depending on the PCB power and ground plane sizes. Would this parallel plate capacitance cause problems to the SR?

I don't have any ideas about the "ESR" of the power and ground plane capacitance so I don't know the answer.
Click to expand...

Don't worry. Just use reactance calculator, something like this: http://www.electronics2000.co.uk/calc/reactance-calculator.php

100pF @ 100MHz will give you 15.9R and capacitor's own ESR is way lower and can be neglected.
And super regulator will run out of steam (gain) looong before that :D
 
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H

HiFiNutNut

Member
Joined 2004
stormsonic said:
Don't worry. Just use reactance calculator, something like this: http://www.electronics2000.co.uk/calc/reactance-calculator.php

100pF @ 100MHz will give you 15.9R and capacitor's own ESR is way lower and can be neglected.
And super regulator will run out of steam (gain) looong before that :D
Click to expand...

Thanks. At what frequency does the SR run out of steam?

A related question is, how much capacitive load can the SR stand before runs out of phase margin? We know there is a medium to high ESR 100uF at the output of the SR. But I don't know if another 100uF or so capacitance at the load would cause problem or not. It has been saying that 100uF as the load. What I am not sure is that if that 100uF refers to the output capacitor or the capacitance at the load (which means 200uF altogether).
 
K

kamis

Member
Joined 2006
jan.didden said:
As long as the heatsink is floating, not connected to anything, I never do it.
I do use some grease or a thermal rubber sheet to aid heat transfer.

Jan[/QUOTE
Thermal rubber sheets are insulators which in fact degrade heat transfer between device and heatsink. adding about 0.4C/W thermal resistance, acting as using smaller radiator.
Thin layer of thermal grease improves heat transfer.
Click to expand...
 
jan.didden

jan.didden

AX tech editor
Joined 2002
linearaudio.net
Paid Member
kamis said:
jan.didden said:
As long as the heatsink is floating, not connected to anything, I never do it.
I do use some grease or a thermal rubber sheet to aid heat transfer.

Jan[/QUOTE
Thermal rubber sheets are insulators which in fact degrade heat transfer between device and heatsink. adding about 0.4C/W thermal resistance, acting as using smaller radiator.
Thin layer of thermal grease improves heat transfer.
Click to expand...

ALL insulators add thermal resistance, one more than the other. Whether any material, be it grease or rubber or whatever, decreases or improves total heat transfer depends on what it was without it. A not very flat heatsink coupled to not very flat heat tabs on a device can benefit from a material that fills the void.

Grease fills that better but rubber is much less messy than grease so if the situation allows it, it's a nice solution.

Jan
Click to expand...
 
K

kamis

Member
Joined 2006
Silicone rubber pads are more practical replacement for mica+thermal grease insulators.But for direct transistor to heatsink mounting, grease,which is itself insulator, in thin layer ,reduces thermal resistance. The same with heatsink bracket/heatsink interface.Silicone pads here degrade performance, and even direct contact is better.
All in all rubber insulators and thermal grease have different application.
Rubber insulators are slightly worse equivalent of mica washers and thermal grease combination, only where electrical conduction is not desirable.
 
K

kamis

Member
Joined 2006
I built +/-30V SR to power my Xono phono preamp. I tested it with OPA604 op-amp, but I have also AD817, LME 49710, AD 825, OPA134 and NE 5534 .
Which is the most suitable for low noise application as in my case? For headphone amp higher noise AD 815 is probably the best .Output voltage is rock solid even with NE5534. Aries pin headers are very practical for SMD/DIP adapters.
 
M

mroether

Member
Joined 2003
Wiring and Grounding

Hi there,
I am trying to build my first diy project.

I read a lot but I am still not sure how to do the wiring and grounding - especially when using the super regulators. My best guess so far is depicted in the images below.

I would like to use four superregs (SR) (2 x pos and 2 x negative power supplies).

Could you guy please help me with my remaining questions:
1. Grounding that avoid potential ground loop problems
- Does it make sense to connect the input ground the potentiometer and to the chassis?
- Is it possible to connect the headphone jack GND as depicted?
- Does the potentiometer GND L / R connected to the superregs make any sense?
- Will the grounding in picture 1 work?

2. Unregulated DC
- I am not sure if I should use 2 x 1,000uF capacitors before SR?

I highly appreciate your comments.

Kind regards

Michael
 

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A

AndrewT

R.I.P.
Joined 2004
Does it make sense to connect the input ground the potentiometer and to the chassis?
Click to expand...
the volume potentiometer is part of the signal input circuit.

It is NOT part of the Chassis.

The input socket has two wires. Those two wires feed the vol pot.
The vol pot has two output wires. Those two wires feed the two input pads of the mono PCB.

If the vol pot has a metal body, or a metal securing thread, then that metal should be connected to chassis.

Your right hand diagram is wrong.
You have connected the input RCAs to Chassis. Remove this connection.
You have connected the vol pots to Power Zero Volts. Remove this connection.
 
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jan.didden

jan.didden

AX tech editor
Joined 2002
linearaudio.net
Paid Member
AndrewT said:
the volume potentiometer is part of the signal input circuit.
It is NOT part of the Chassis.
[snip]
Your right hand diagram is wrong.
You have connected the input RCAs to Chassis. Remove this connection.
You have connected the vol pots to Power Zero Volts. Remove this connection.
Click to expand...

Indeed, fully agree.
Otherwise, the raw DC routing is spot on.

an
 
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