The simplistic Salas low voltage shunt regulator - Page 3 - diyAudio
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Old 9th May 2009, 12:53 AM   #21
iko is offline iko  Canada
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james, good to hear about the CT stuff. I'll have to try that. Could it be that it's responsible by itself for the black background you're experiencing?

Alright, the pcb, let's see, I have a few comments.

1. Considering that there are people that would only use the + version, perhaps it's best to have them separate.
3. Using a jfet instead of R10 improves very slightly the ripple rejection in simulation. However, it may not be audible; if the pcb had two holes on one side people can fit either a resistor, or the jfet. Easy thing to accommodate.
4. Did you notice the sharp dip at low frequency in the ripple rejection bode plot? C1 is responsible for that. There is a nasty phase thing there too. A small size resistor smooths it out. Again, we could simply omit it, or allow for it, and who doesn't want it just passes it over with a jumper? Up to you.
5. I could see no difference without it. salas, did it make a difference for you?
6. Is it necessary? Recommended?

IMHO, the fewer parts, the better. I would stick with choosing the right zener for the desired output voltage. A 50R resistor above the zener seems to slightly affect the output impedance, while raising the voltage by about 0.4V.

A word of caution on one part of the layout. The traces around M2 are very important. They should be as short as possible. The slightest inductance there decreases the output impedance by a lot.



Quote:
Originally posted by jameshillj

1. One pcb for + and - rails?
2. Using inverted 2skk170s rather than j74? or other devices, pinouts?
3. pads for a k170 option for R10?
4. extra Resistor as per your new Cct in series with C1 or is that a SIM thing?
5. Is there a Resistor between j1 source and 0v?
6. Is there to be a Resistor between the Shunt M2 and 0v?

I would like a small adjustment to the voltage - about 0.5 volts to compensate for zeners, correct for amp offset, etc, etc. Would a small pot (50R?) between zener and rail stuff up the performance?
Could you check this out with your magic circuit cruncher thing!!

Suggestions are MOST WELCOME - I'll start out with the extra tracking that we learned about with the Toole shunt layout and see what happens.

I'll get started into the pcb tomorrow (or today actually!)

For now ... Jh
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Old 9th May 2009, 01:04 AM   #22
Salas is offline Salas  Greece
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5 & 6. If its high quality high frequency and low esr, it helps. If not, better avoid. More interaction than filtering. Better with some passive pre filtering. No difference even in your sim with the cap or without it?
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Old 9th May 2009, 01:38 AM   #23
iko is offline iko  Canada
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Quote:
Originally posted by Salas
5 & 6. If its high quality high frequency and low esr, it helps. If not, better avoid. More interaction than filtering. Better with some passive pre filtering. No difference even in your sim with the cap or without it?
Sorry, salas, I don't know which cap and sim you're referring to?
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Old 9th May 2009, 01:39 AM   #24
Salas is offline Salas  Greece
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100u bootstrap cap, top left, or left most.
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Old 9th May 2009, 01:44 AM   #25
jkeny is offline jkeny  Ireland
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Can somebody define the voltage & current operating range of this regulator?
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Old 9th May 2009, 02:01 AM   #26
mikelm is offline mikelm  England
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Salas,

I have some irf530n's so if I buy some irf9530n's I will have enough for some dual supplies.

do you think these will sound ok or was irfp9240 your special choice ?

thx

mike
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Old 9th May 2009, 02:08 AM   #27
Salas is offline Salas  Greece
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Quote:
Originally posted by jkeny
Can somebody define the voltage & current operating range of this regulator?
It has been made from 13V to +/-46V. From 90mA to 3A, I know of regs in service. Also jwb made it at 9V.
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Old 9th May 2009, 02:13 AM   #28
Salas is offline Salas  Greece
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Quote:
Originally posted by mikelm
Salas,

I have some irf530n's so if I buy some irf9530n's I will have enough for some dual supplies.

do you think these will sound ok or was irfp9240 your special choice ?

thx

mike
With 9610s I know it works faster. It will be more open in bandwidth with 530s too. The 9240 I know it will not oscillate with non careful layout, and it sounds OK. Hefty. You may make it with 530s and let us know. In general I don't go recommending bandwidth more than needed.
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Old 9th May 2009, 02:15 AM   #29
iko is offline iko  Canada
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Quote:
Originally posted by Salas
100u bootstrap cap, top left, or left most.

It makes a big difference in the ripple rejection. I'll show you the plots later with and without. You're right, one can prefilter.

jkeny, the output voltage will be dependent on the zener used. The input voltage should be between 5 and 10 volts higher than the desired output; you need the voltage drop for good regulation.
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Old 9th May 2009, 02:17 AM   #30
Salas is offline Salas  Greece
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My best there was NOS Panasonic HFZ. So keep it. I don't know if the notch will be there with any cap make or grade, so better have 1R option on the PCB?
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