Placid-BP Bipolar Shunt Regulated Power Supply

Russ White · 2011-02-09 5:12 am

When I designed the placid I used smoothing caps that were really intended for about 350-400ma load max. So if there were anything one could do to make it better suited to a higher current load it would be simply adding some capacitance after the rectifiers. For up to 1A 4,700-10,000uf would be very good. But keep in mind, heat sinks will also become a limiting factor.

Cheers!
Russ

Jeffrey Davison · 2011-02-09 5:54 am

Perhaps taller heat sinks with the same footprint? (case height the limiting factor... also the Trident also take up a wee bit of air space too).

JD

Russ White said:
When I designed the placid I used smoothing caps that were really intended for about 350-400ma load max. So if there were anything one could do to make it better suited to a higher current load it would be simply adding some capacitance after the rectifiers. For up to 1A 4,700-10,000uf would be very good. But keep in mind, heat sinks will also become a limiting factor.

Cheers!
Russ

Russ White · 2011-02-09 1:12 pm

Jeffrey Davison said:
Perhaps taller heat sinks with the same footprint? (case height the limiting factor... also the Trident also take up a wee bit of air space too).

JD

Sure you could use taller HS, or mount the power transistors direct to the case or a large flat heat sink.

Beefy · 2011-02-09 4:48 pm

I used 2.5" sinks with my Placid BP, and it definitely improves the thermals.

MartinC700 · 2011-02-10 5:34 am

Russ White said:
When I designed the placid I used smoothing caps that were really intended for about 350-400ma load max. So if there were anything one could do to make it better suited to a higher current load it would be simply adding some capacitance after the rectifiers. For up to 1A 4,700-10,000uf would be very good. But keep in mind, heat sinks will also become a limiting factor.

Cheers!
Russ

Thanks Russ. I do have a fair amount of extra capacitance than the stock board anyway so that's good news. As you mentioned in a seperate post, mounting the transistors of the placid to the case makes sense for high current apps, unfortunately too late in my case design to do that so I added a large number of cooling vents.

Regards

Martin

PS - So you homebrew too? must be something about DIY DAC's and DIY beer - just about to sit down to some music and a homebrew dry stout...cheers!

Russ White · 2011-02-10 1:59 pm

I do brew beer as well. I have three kegs in the fridge right now and several fermenters going under the house, mostly filled with lagers. In the fridge is a Kölsch (session beer), an imperial IPA(1.087 O.G), and a winter stout with a ridiculous grain bill (about 22lbs) for a 5 gallon batch.

Its funny I have run into several DIY audio homebrewers.

It must be a common gene or something.

Cheers!
Russ

natzev_i · 2011-02-14 2:58 pm

Russ White said:
When I designed the placid I used smoothing caps that were really intended for about 350-400ma load max. So if there were anything one could do to make it better suited to a higher current load it would be simply adding some capacitance after the rectifiers. For up to 1A 4,700-10,000uf would be very good. But keep in mind, heat sinks will also become a limiting factor.

Cheers!
Russ

Russ, what fixed value of R1 should be used in order for the Placid to power BII with Tridents, please? Is there anything else I need to change?
Thank you

Russ White · 2011-02-15 1:24 pm

It is difficult to say exactly what value R1 should be because the reference voltage can vary. Just use the pot to adjust it. Then if you like you can measure the actual resistance and replace the pot with a resistor.

natzev_i · 2011-02-15 1:45 pm

Russ White said:
It is difficult to say exactly what value R1 should be because the reference voltage can vary. Just use the pot to adjust it. Then if you like you can measure the actual resistance and replace the pot with a resistor.

Thanks, Russ! So, this and bigger cap & heat sinks is the only things I need to do to power BII + Tridents with the Placid?
What other cap value will you suggest for the purpose since 4700 - 10000uF, 35V are too large to fit on the PCB, please?

BrianDonegan · 2011-02-15 2:24 pm

natzev_i said:
Thanks, Russ! So, this and bigger cap & heat sinks is the only things I need to do to power BII + Tridents with the Placid?
What other cap value will you suggest for the purpose since 4700 - 10000uF, 35V are too large to fit on the PCB, please?

You don't really "need" to do any of these things, but they certainly will not hurt. The supplied heatsinks will work fine, and with the supplied caps, you will have slightly higher voltage ripple, but it will be easily taken care of locally by the Tridents and AVCC shunts. You don't even need to change the stock trimmer.

natzev_i · 2011-02-15 2:35 pm

Thanks, Brian - I just wanted to play on the safe side.
Is it a good idea to use LCDPS (which I already have) along with Placid in order to spread more even the consumed power? Let's say to power the digital part with LCDPS and the analogue with Placid?

LeonvB · 2011-02-15 6:12 pm

That would be a good idea: the digital part is already taken care of with the Tridents. You could use half a LCDPS to power a BII + Trident set, and use a Placid for other modules.

natzev_i · 2011-02-15 7:19 pm

LeonvB said:
That would be a good idea: the digital part is already taken care of with the Tridents. You could use half a LCDPS to power a BII + Trident set, and use a Placid for other modules.

I even thought to use 1/2 LCDPS to power the XO Trident only, the other 1/2 for the other two Tridents and the Placid for the AVcc. Don't know if I will hear any differences, though

LeonvB · 2011-02-15 7:32 pm

Interesting thought, perhaps using 2 LCDPS's would be better though: you could separate the other Tridents too that way.

natzev_i · 2011-02-15 7:35 pm

You know, this is going to be endless, Leon

BrianDonegan · 2011-02-15 7:35 pm

You would need to cut traces on the BII board, and for little (if any) benefit.

natzev_i · 2011-02-15 7:53 pm

BrianDonegan said:
You would need to cut traces on the BII board, and for little (if any) benefit.

The only benefit I see for sure is Placid will work in its optimum conditions.
Since I do have LCDPS and Placid boards anyway I might give them a try.

Brian, what current I need to set the Placid for to power AVcc module only, please? The same way it is set for the BII without Tridents or less?

tubeme · 2011-09-17 8:59 pm

Placid HD BP tuning/testing

Could anybody help with Placid HD BP tuning/testing?

I've set VR1A/B to 450R and VR2A/B to 1K as manual says. Turn the power on and what I have:

Input after transformer: 14.9 VAC and 14.6 VAC

TP_VIN+ with TP_CCS+ says 0.593 VDC (593 mA?)
TP_VIN- with TP_CCS- says -0.764 VDC (764 mA?)

TP_GND2 with TP_VREF1+ 3.76 VDC
TP_GND2 with TP_VREF2- -3.78 VDC

TP_GND2 with TP_OUT+ 14.88
TP_GND2 with TP_OUT- -14.05

TP_SHUNT with TP_OUT+ 585 mA
TP_GND2 with TP_OUT- 790 mA

I can change TP_OUT+ with VR2A from +14.9 to 18 V only and TP_OUT- is not changing when I turning VR2B it just stays -14.04!

I thought that VRs are dead after my soldering. But I've turned off PSU, waited and measured resistance of VR1A/B and VR2A/B with turning.
VR1A 8.07K-1.8R
VR1B 9.86K-1.2R
VR2A 0.9R-9.37K
VR2B 0.8R-9.92K

Where should I check? What can be wrong?

Russ White · 2011-09-17 9:08 pm

It could be an issue around the discrete error amplifier. You may want to start a thread on our support forum and post some pictures if you can.

reo · 2011-09-17 11:35 pm

Hi
Taken from a previous quote .. LeonvB That would be a good idea: the digital part is already taken care of with the Tridents.
The analogue part is taken care of with .........
regards
rol

Placid-BP Bipolar Shunt Regulated Power Supply

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