Salas hotrodded blue DCB1 build - Page 267 - diyAudio
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Old 9th February 2013, 12:14 AM   #2661
stajo is online now stajo  Sweden
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Mea culpa Obi-Wan. I did not explain myself properly. I used a pre C-R filter before the shunts filtercaps. That is 4700-5,6. The 25 V caps I got worried me and my trafo is some volt high. After that is standard 4700+4700 and setter is R10 per rail. On the 4 card pic I use an R1 per plus and minus for the lot.

You had the 10 ohm setter in mind for adjusting sire?

/C3PO

Last edited by stajo; 9th February 2013 at 12:25 AM.
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Old 9th February 2013, 01:15 AM   #2662
Salas is offline Salas  Greece
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Yes. Your currents are normal for 10R. And its a nice spot circa 200mA for most users, that is why I got it as standard setting from the beginning. Your sinks look more potent though. You say you are with the Jedi but your yield looks suspiciously Dark Star...
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Old 9th February 2013, 01:29 AM   #2663
stajo is online now stajo  Sweden
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The sinks are potent sire. Just above fingerwarm after chewbacka has run them for 1 hr warpspeed.
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Old 10th February 2013, 01:46 PM   #2664
stajo is online now stajo  Sweden
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Quote:
Originally Posted by Salas View Post
25% smaller setter for positive can give more balanced CCS with the benefit of hindsight if for newer current level test.
I'm not absolutely sure that I understood you correctly there Master but parallelling the negative 10R setting resistor with a 56R gives me approx 8,2R and results in a drop over the same at 1,637 volt, equaling 190 mA. Keeping the positive at 10R drops 1,915, equaling 191 mA.

Please note that this is measures over the setting resistor, yesterdays data was from 5,6R in pre filter.

Vout buffer says -10,7 +10,4 and offset 0,7 mV left and 0,6 mV right.
Click the image to open in full size.

Last edited by stajo; 10th February 2013 at 01:57 PM.
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Old 10th February 2013, 03:57 PM   #2665
Salas is offline Salas  Greece
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Yes you got it. Trimming down the Rset unequally to compensate for the NMOS PMOS Vgs difference part of the current setting scheme in this schematic. Not something particularly useful in practice since at those regions the transconductance isn't differentiating enough with few mA, but aesthetically nice to have equal measurements in the CCSs. All MOSFETS in each board give out same heat at least now.

P.S. Yes, negative side in this case. Correct. Whatever side is weaker for any reason be it different LEDS or MOSFETS for that matter.
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Old 10th February 2013, 10:53 PM   #2666
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Quote:
Originally Posted by stajo View Post
Phew. Drilling and threading 32 M3s pulls me to the dark side. It took almost 3 sixpacks and in the end I was almost in to the ethyl alcohol. But now sits here 4 stuffed boards.
Click the image to open in full size.
I did some measures feeding them 1 by 1 by the trafo and two 5R6 ( closer to 5R5 actually) on the rectified plus and minus.
Click the image to open in full size.

Im gonna try make a chart. First column is card, 1, second card 2 etc:

Voltage drop 5R5:.....0,988/1,260.......0,910/1,183......0,979/1,194.....0,975/1,188

Makes current mA:....180/229.............165/215...........178/217..........177/216

Vout buffer (-/+):.....10,01/9,98........10,11/10,09........10,08/10,04...10,07/10,05

First is negative rail, second is positive on all above.

DC offset L/R mA:......0,3/1,1...............0,7/1,6............0,04/2,8.........1,5/2,2

So, positive takes more current then negative but outputs slightly less Vout.

What does the Jedi Council say. Am I still with the rebels or should I go talk to the man in the mask (I.e. do you think I should plug it in)?

Staffan
So - where did you get those heat sinks?
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Old 11th February 2013, 04:50 AM   #2667
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Can I get away with a transformer with 18V secondaries? PSU caps will be 60V rated... still planning on 10R resistors although I should have enough heat sink to go down to 5R or perhaps 3R. Any other special considerations or adjustments required?
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Old 11th February 2013, 05:20 AM   #2668
stajo is online now stajo  Sweden
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Originally Posted by schubert View Post
So - where did you get those heat sinks?
Its Fisher and I got them from here https://www.elfa.se/elfa3~se_sv/elfa...=0&q=75-592-30

Staffan
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Old 11th February 2013, 05:26 AM   #2669
Salas is offline Salas  Greece
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Quote:
Originally Posted by oneplustwo View Post
Can I get away with a transformer with 18V secondaries? PSU caps will be 60V rated... still planning on 10R resistors although I should have enough heat sink to go down to 5R or perhaps 3R. Any other special considerations or adjustments required?
If your sinks still keep the CCS Mosfets at tolerable heat on their plastic cases then you can use all that extra VAC. Non efficient, but if you must...
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Old 11th February 2013, 02:58 PM   #2670
stajo is online now stajo  Sweden
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Originally Posted by oneplustwo View Post
Can I get away with a transformer with 18V secondaries? PSU caps will be 60V rated... still planning on 10R resistors although I should have enough heat sink to go down to 5R or perhaps 3R. Any other special considerations or adjustments required?
I would load it down with around 30 down to 12-15 ohm resistor after rectifiers and cap, do some math and see what your up against to burn. One volt up and down counts under those circumstances.

Staffan
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