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Old 5th September 2011, 10:20 PM   #341
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So, is it better a BJT configuration than a mosfet one, for a Buffalo Dac? (5.3V-575mA)
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Old 5th September 2011, 10:31 PM   #342
Salas is offline Salas  Greece
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Both can work 5V up, I don't have a Buffalo to measure noise floor or listen so to tell you for sure. You Buffalo people are going to find the most agreeable configurations by tests.
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Old 6th September 2011, 12:02 AM   #343
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Default I used...

MOSFET for my B-II. With two green leds and one 220R for Vref (no trimmer) I got just about perfect 5.3 volt output. Used a Silmic II 220 uF for Vref filter, and the sound is fantastic. Have not tried BJT, but really no reason to for me.
Remember this is just a pre-reg in this case, so the onboard regs will probably have more effect on the final sound.
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Old 6th September 2011, 10:45 AM   #344
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Quote:
Originally Posted by barrows View Post
Remember this is just a pre-reg in this case, so the onboard regs will probably have more effect on the final sound.
YES, I changed Tridents for BiB BJT positive very important each reg with is own tx (quality tx very audible so better R-Core minimum for clock reg)
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Old 9th September 2011, 06:34 PM   #345
dodo is offline dodo  Poland
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In the BIB instruction there is a description
".....Current draw: 100mA minimum ..."
is it caused by the power disspation limitations of the Q206;Q106;Q306 ???
or it's another reason for such limitations ?

If the circuit power demand is around 10-20mA (one side[+ or -] ; one chanel) can I use BIB shunt regulator , making CCS around 100mA ???
(considering the fact I would use 4 regulators separately for each channel , each supply side )??

Last edited by dodo; 9th September 2011 at 06:37 PM.
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Old 9th September 2011, 09:43 PM   #346
Salas is offline Salas  Greece
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Its a performance advised CCS minimum to keep the power elements conducting enough current for good output impedance. Not the minimum load draw. Yes, I would recommend you keep it at 100mA CCS. If its absolutely needed it will still work with 20mA margin above load consumption.
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Old 10th September 2011, 12:06 AM   #347
alazira is offline alazira  United States
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Quote:
Originally Posted by merlin el mago View Post
YES, I changed Tridents for BiB BJT positive very important each reg with is own tx (quality tx very audible so better R-Core minimum for clock reg)
After Merlin el Mago's glowing report on replacing buffalo tridents, I threw together a 3.3V BiB without measuring K117 Idss or LED Vf.

Russ says the tridents R4 sets the max current (the 3.3V versions use 20R so: 1.2V/20R=60mA), but actual circuit draws as reported by Nicmac are:
VDD (1.2V): 90-115 mA
DVCC (3.3V): 16 mA
VDD_XO (3.3V): 13 mA

Based on that info I used a 39R dummy load (3.3V/39R=85mA), R101 set at 12R (1.96V/12R=163mA), one Red LED + 238R in Vref area, three green LED's.
Stable 3.3V with small 10gram Al heatsinks (40degC). I've yet to hook it up though.

The manual says BJT can provide as low as 2.5V output. Is there a way to achieve 1.2V?

Thanks to Salas and TeaBag for this cool project. I have a 4wire Kelvin ohm meter that is super accurate and now I can see why.
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Old 10th September 2011, 01:54 AM   #348
Salas is offline Salas  Greece
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You can push your luck by using just a 1N4003 etc. diode as Vref I guess. Or just a 500R trimmer. 2.5V is the limit if with only one 1.9V LED as it normally uses and it contains its error amp voltage needs decently. I don't expect the Zo performance to remain intact when the error amp and its CCS Jfet will be squeezed at their very limit, but it could be passable. Vin must not be lower than what the 3 LEDs drop plus ~1V even if you will go very low Vout, by the way.
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Old 10th September 2011, 01:48 PM   #349
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Default 1.2V Vout

Quote:
Originally Posted by alazira View Post
After Merlin el Mago's glowing report on replacing buffalo tridents, I threw together a 3.3V BiB without measuring K117 Idss or LED Vf.

Russ says the tridents R4 sets the max current (the 3.3V versions use 20R so: 1.2V/20R=60mA), but actual circuit draws as reported by Nicmac are:
VDD (1.2V): 90-115 mA
DVCC (3.3V): 16 mA
VDD_XO (3.3V): 13 mA

Based on that info I used a 39R dummy load (3.3V/39R=85mA), R101 set at 12R (1.96V/12R=163mA), one Red LED + 238R in Vref area, three green LED's.
Stable 3.3V with small 10gram Al heatsinks (40degC). I've yet to hook it up though.

The manual says BJT can provide as low as 2.5V output. Is there a way to achieve 1.2V?

Thanks to Salas and TeaBag for this cool project. I have a 4wire Kelvin ohm meter that is super accurate and now I can see why.
Thanks for the info about Tridents consumption so I can adjust accordingly because I need to reduce the hot at the maximum inside the box.

For 1.2V I use Salas SS1Vs regulator as per Disco's schematic

Click the image to open in full size.

Last edited by merlin el mago; 10th September 2011 at 01:57 PM.
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Old 10th September 2011, 02:00 PM   #350
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A pic of my Salas SSlv1S regulator 1.2V Vout 360mA as per Disco's schematic just for fun
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