Fortunately only do the mistake measuring wrong resistors, now all is ok, I connected the IVY III & adjusted the voltage R13 & R14 to 0,05V
Thank you very for your help.
Now I'm waiting the trimmer 200ohms to setup mine other Placis for the BII (I received 2 trimmers 10K instead one1 10K & one 200 ohms) but don't worry Brian knows because I & send him an e-mail & he answered that will send me the trimmer.
Thank you very for your help.
Now I'm waiting the trimmer 200ohms to setup mine other Placis for the BII (I received 2 trimmers 10K instead one1 10K & one 200 ohms) but don't worry Brian knows because I & send him an e-mail & he answered that will send me the trimmer.
Brian have taken care of me offline. Thanks you guys for the great work and great support!
Stanley
I would use the first, although you cannot wire it the way you have it.
You could do the second option, but I think it's probably a waste of time, but don't let me stop you.
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hello
I would ask help, before making trouble ...
tensions (+5.50 ve +15 v - 15v), the two power supply, the buffalo dac II and to the Ivy III, I have to adjust.... with the DAC and IVY III connected or disconnected?
I noticed that if you adjust the voltage to +15 V and-15V without load, then when I connect the IVY III, the voltage drops to approximately +9 V .... Is this normal?
I would ask help, before making trouble ...
tensions (+5.50 ve +15 v - 15v), the two power supply, the buffalo dac II and to the Ivy III, I have to adjust.... with the DAC and IVY III connected or disconnected?
I noticed that if you adjust the voltage to +15 V and-15V without load, then when I connect the IVY III, the voltage drops to approximately +9 V .... Is this normal?
Hi all, Brian, Russ,
Finally got my Placid BP (v2.1.1) up and running. It sat for quite a while due to other home and family projects...
Had some issues. First I thought I had burned up one of the opamps. Seems that may not have been it.
First thing I noticed was that I couldn't get the voltage above ~ 11V from the + rail. (the - rail was fine all along) I think part of this was a cold solder on QP1 and QP2.
Then I got that worked out, but couldn't get the current across R17 > 100mA. I Pulled my hair out for a bit, then discovered the threads on TP site about the varying Idss on the JFETs that were sent out.
Getting 0.25V across R17 - Placid Dual Power Supply - Twisted Pear Audio Support
jumpering R6 got me to a normal range, so I was happy. I only need about 80mA anyway, so in the end I left R6 as is. Now that I know everything is OK.
After some changes in plans, it's "only" powering a ballsie. Sounds great so far!
Note about cold solder:
I used to be able to solder. Got out of practice. Now that I have a proper temp adjustable station I'm even worse. I also finally got a proper range of tips. The small tip that came with the station was definitely making it hard for me to get some of the larger PCB traces warmed up At least I'm getting some practice again
Finally got my Placid BP (v2.1.1) up and running. It sat for quite a while due to other home and family projects...
Had some issues. First I thought I had burned up one of the opamps. Seems that may not have been it.
First thing I noticed was that I couldn't get the voltage above ~ 11V from the + rail. (the - rail was fine all along) I think part of this was a cold solder on QP1 and QP2.
Then I got that worked out, but couldn't get the current across R17 > 100mA. I Pulled my hair out for a bit, then discovered the threads on TP site about the varying Idss on the JFETs that were sent out.
Getting 0.25V across R17 - Placid Dual Power Supply - Twisted Pear Audio Support
jumpering R6 got me to a normal range, so I was happy. I only need about 80mA anyway, so in the end I left R6 as is. Now that I know everything is OK.
After some changes in plans, it's "only" powering a ballsie. Sounds great so far!
Note about cold solder:
I used to be able to solder. Got out of practice. Now that I have a proper temp adjustable station I'm even worse. I also finally got a proper range of tips. The small tip that came with the station was definitely making it hard for me to get some of the larger PCB traces warmed up
At least I'm getting some practice again
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sounds like your current is not set high enough for the load. Did you check the current? -- the voltage across R1 & R2 on most recent PlacidBP's
(Older PlacidBP's were R17 & R18...) See the manual....
I received a Placid power supply a little while ago and just finally got around to implementing it. Thought I'd post a few comments and suggestions, sort of a mini-review.
Overall, very good board layout, price is decent. I was using a 2x15V secondary transformer with +/-12VDC outputs. I measured about 400uVrms of noise on an output with a 150mA load and 225 mA through the CCS (shunting 75mA). This was even without the best test setup, using an HP 403B. For comparison, a 7812 makes about 1.6mVrms of noise.
My only suggestions would be to:
1) Add test points for R1 and R2. I was using a meter to measure current across them, when one of the meter lead tips peeked through the soldermask and shorted, ruining one of current-setting potentiometers (VR1/VR2).
2) Ship with 50-ohm variable potentiometers instead of 200-ohm. Most of the turning range is wasted getting the current close to most applications (> 25mA).
Otherwise, very nice product!
Overall, very good board layout, price is decent. I was using a 2x15V secondary transformer with +/-12VDC outputs. I measured about 400uVrms of noise on an output with a 150mA load and 225 mA through the CCS (shunting 75mA). This was even without the best test setup, using an HP 403B. For comparison, a 7812 makes about 1.6mVrms of noise.
My only suggestions would be to:
1) Add test points for R1 and R2. I was using a meter to measure current across them, when one of the meter lead tips peeked through the soldermask and shorted, ruining one of current-setting potentiometers (VR1/VR2).
2) Ship with 50-ohm variable potentiometers instead of 200-ohm. Most of the turning range is wasted getting the current close to most applications (> 25mA).
Otherwise, very nice product!
It got to be lower noise than that?. I am not sure how your measurements relate to specifications, but:
According to specifications, an lt1763 regulator is about 8x lower noise than a 78xx class regulator: H I F I D U I N O: Comparing Noise Figures in Linear Regulators
Your measurements show that the Placid is 4x lower noise than a 7812. Does this mean that a lt1763 regulator is 1/2 the noise than a Placid? It seems that from a design point of view (filtered LED reference, low noise opamp and low noise pass transistors) the Placid should be lower noise than an IC regulator using a bandgap reference
The placid very well could ideally be lower noise, however, that is what I measured, under a non-ideal situation (e.g. inside a chassis with other electronic components). Also keep in mind that the LT1763 series only go up to 5 Volts. Noise would likely go up when using a voltage divider for the reference rather than directly connecting the output to the reference (for 12V output).
Hi,
I'm waiting for the next batch of Buffalo IIs and am reading a bit in the mean time
... I just noticed that Placid BP bom says:
"IC1, IC2 2 Precision Low-noise Bipolar Op Amp Burr-Brown OPA227PA Mouser 595-OPA227PA"
but I can see on the picture that your latest boards use SMD versions, don't they?
Ivica
I'm waiting for the next batch of Buffalo IIs and am reading a bit in the mean time
... I just noticed that Placid BP bom says: "IC1, IC2 2 Precision Low-noise Bipolar Op Amp Burr-Brown OPA227PA Mouser 595-OPA227PA"
but I can see on the picture that your latest boards use SMD versions, don't they?
Ivica
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