Go Back   Home > Forums > Commercial Sector > Manufacturers > Twisted Pear

Twisted Pear Superior quality electronic kits

Reply
 
Thread Tools Search this Thread
Old 25th April 2010, 05:55 PM   #111
diyAudio Member
 
eclectic2k's Avatar
 
Join Date: Nov 2005
Location: Silicon Valley
Quote:
Originally Posted by alboran View Post
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?
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....
  Reply With Quote
Old 5th June 2010, 05:18 AM   #112
diyAudio Member
 
Join Date: Mar 2009
Hi Brian and Russ,

The manual recommends a 7v transformer for the Placid Power Supply. Is is okay to use a 9v transformer, or would the extra voltage drop create too much heat? (350mA, 5.5v output)
  Reply With Quote
Old 5th June 2010, 11:49 AM   #113
diyAudio Member
 
BrianDonegan's Avatar
 
Join Date: Dec 2004
Location: Rock Ridge
Quote:
Originally Posted by chipzahoy View Post
Hi Brian and Russ,

The manual recommends a 7v transformer for the Placid Power Supply. Is is okay to use a 9v transformer, or would the extra voltage drop create too much heat? (350mA, 5.5v output)
It should be >=7V for 5V use. We sell a 9V transformer for it.
__________________
Twisted Pear Audio
  Reply With Quote
Old 5th June 2010, 08:37 PM   #114
diyAudio Member
 
Join Date: Mar 2009
Thank you Brian! I'll pair a 9v transformer with the Placid
  Reply With Quote
Old 26th July 2010, 08:48 PM   #115
diyAudio Member
 
Boris_The_Blade's Avatar
 
Join Date: Mar 2007
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!
  Reply With Quote
Old 9th August 2010, 09:01 PM   #116
glt is offline glt  United States
diyAudio Member
 
Join Date: Oct 2004
Quote:
Originally Posted by Boris_The_Blade View Post
...
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.

...
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
__________________
www.hifiduino.wordpress.com
  Reply With Quote
Old 10th August 2010, 04:40 PM   #117
diyAudio Member
 
Boris_The_Blade's Avatar
 
Join Date: Mar 2007
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).
  Reply With Quote
Old 10th August 2010, 04:42 PM   #118
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Send a message via Yahoo to Russ White
All things considered its not a bad measurement at all.
__________________
Less pulp more juice Twisted Pear Audio.
  Reply With Quote
Old 10th August 2010, 04:43 PM   #119
diyAudio Member
 
Boris_The_Blade's Avatar
 
Join Date: Mar 2007
Quote:
Originally Posted by Russ White View Post
All things considered its not a bad measurement at all.
I agree completely.
  Reply With Quote
Old 15th October 2010, 10:54 PM   #120
diyAudio Member
 
Bassivus's Avatar
 
Join Date: Aug 2004
Location: Novi Sad, Vojvodina
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
__________________
...is I disappear. There is ONLY the music.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Shunt-regulated 24V DC Power Supply for Preamp Modules snoopyma Power Supplies 31 16th January 2010 03:05 PM
Bipolar Power supply IC argonrepublic Parts 1 6th December 2008 07:24 PM
Regulated Power Supply. Bipolar, JFET or MOS? Kenneth Zhu Tubes / Valves 4 30th December 2007 08:30 AM
Shunt-regulated 24V DC Power Supply for Preamp Modules snoopyma Solid State 0 25th August 2005 04:58 PM
power supply: shunt or series?? AudioGeek Solid State 34 25th July 2004 02:02 AM


New To Site? Need Help?

All times are GMT. The time now is 02:06 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2