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-   -   The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb.html)

jwjarch 30th April 2019 11:48 PM

PM sent, X! Thanks!

xrk971 1st May 2019 02:26 AM

GB status update
Quote:

baswamin - 2 boards - invoice sent
meanie - 2 boards
jwjarch - 2 boards - invoice sent
gary s - 2 boards - Paid
nautibuoy - 2 boards
antoniopf1972 - 2 boards - invoice sent
ravid - 2 boards - invoice sent

antoniopf1972 1st May 2019 02:36 AM

Payment sent. Thank you

Gricko 1st May 2019 06:02 AM

SLB
 
baswamin - 2 boards - invoice sent
meanie - 2 boards
jwjarch - 2 boards
gary s - 2 boards - invoice sent
nautibuoy - 2 boards
antoniopf1972 - 2 boards
ravid - 2 boards
Gricko - 2 boards

poseidonsvoice 1st May 2019 06:54 AM

baswamin - 2 boards - invoice sent
meanie - 2 boards
jwjarch - 2 boards
gary s - 2 boards - invoice sent
nautibuoy - 2 boards
antoniopf1972 - 2 boards
ravid - 2 boards
Gricko - 2 boards
poseidonsvoice - 2 boards

xrk971 1st May 2019 10:36 AM

GB status update:
Quote:

baswamin - 2 boards - Paid
meanie - 2 boards - need PayPal address
jwjarch - 2 boards - Invoice sent
gary s - 2 boards - Paid
nautibuoy - 2 boards - Need PayPal address
antoniopf1972 - 2 boards - Paid
ravid - 2 boards - Paid
Gricko - 2 boards - Invoice sent
poseidonsvoice - 2 boards - Invoice sent

xrk971 1st May 2019 03:11 PM

GB status update

Quote:

baswamin - 2 boards - Paid
meanie - 2 boards - Invoice sent
jwjarch - 2 boards - Paid
gary s - 2 boards - Paid
nautibuoy - 2 boards - Need PayPal address
antoniopf1972 - 2 boards - Paid
ravid - 2 boards - Paid, Invoice sent for Simple PSU ship same time
Gricko - 2 boards - Invoice sent
poseidonsvoice - 2 boards - Paid
Bkdog - 2 boards - Invoice sent

yoaudio 1st May 2019 08:16 PM

baswamin - 2 boards - Paid
meanie - 2 boards - Invoice sent
jwjarch - 2 boards - Paid
gary s - 2 boards - Paid
nautibuoy - 2 boards - Need PayPal address
antoniopf1972 - 2 boards - Paid
ravid - 2 boards - Paid, Invoice sent for Simple PSU ship same time
Gricko - 2 boards - Invoice sent
poseidonsvoice - 2 boards - Paid
Bkdog - 2 boards - Invoice sent
yoaudio - 2 boards

Mark Johnson 2nd May 2019 06:24 PM

2 Attachment(s)
Quote:

Originally Posted by xrk971 (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5760150.html#post5760150)
We are using KOA Speer non inductive cement filled rectangular metal plate 5W resistors. A pair of 0.1ohm in series passing 5A is dissipating 2.5W ea - well under rating.

Data sheet is page 211:
http://koaspeer.com/pdfs/brochures/KOA_Catalog_2017.pdf

Quote:

Originally Posted by xrk971 (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5760265.html#post5760265)
It's definitely not something you want to grab with your fingers when it is running, but doesn't melt its own solder at least and we are giving it room for air flow. If folks are concerned about keeping temps low, use four 0.22R in series parallel and dissipation will be about 1.25W each for maybe 65C temps.

I added a few of those KOA Speer rectangular metal plate resistors, part type "BPR", to a recent Mouser order. They were less than a dollar, it's a very low cost to perform some fun experiments.

I bought the 1.0 ohm resistor from Mouser, and attached it to my lab equipment using a "4 point Kelvin connection". Current is forced from the red clip to the black clip. Voltage is sensed from the yellow clip to the white clip. Notice that the yellow and white clips are attached in places where the high current is NOT flowing. There is no IR drop to pollute the voltage measurement.

I carefully adjusted the power supply output voltage until 1.5862 volts appeared across the 1 ohm resistor, measured at the yellow clip and the white clip. Thus the power dissipated in the resistor was (1.5862 * 1.5862 / 1.00) = 2.516 watts. That's my best attempt to match the 2.5 watts of dissipation, mentioned in the very first quote above.

I used a Type-K thermocouple to measure the temperature of the BPR resistor body. The thermocouple bulb was pressed onto the resistor body right where the OMEGA symbol is printed, between the 1 and the J. Thermocouple temperature in this position was 95.6 degrees Celsius. Almost hot enough to boil water. Definitely hot enough to burn a hobbyist's fingers.

_

xrk971 3rd May 2019 12:09 AM

96C sounds rigjt - no argument there. I did say you don’t want to grab it with your fingers when it’s running. 96C temp doesn’t bother the part though one bit.


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