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Old 6th September 2008, 01:33 PM   #71
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Yes

I have two rc in pedia dac and in pacific ,I need learnig ....if I remenber well shunt are perfect for clock ...
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Old 6th September 2008, 01:39 PM   #72
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Quote:
Originally posted by salas
A 317 with 22uF bypassed adj leg resistor will get you to -80dB ripple rejection. You can build an R-C filter before the LM317 if you size your transformer's secondary voltage higher. Just use your DMM for current measurement, see your mA draw and size a resistor to drop 10V to the main filter capacitor. See that you can get 43V on LM's input. Size the setting resistors ratio (see data sheet online) for 37V out. That will add some extra dB rejection and will be damping the current draw from the bridge rectifier reducing power rail wide band switching noise.
In my circuit you will need around 13mA per channel. A 8k2 will drop 10.66V. If you use common supply, a 3k9 will drop 10.14V.
Use a zener to limit the input-output differential across the LM317.
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Old 6th September 2008, 01:58 PM   #73
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Also 22uF Silmic for adj bypass and 220uF Silmic at output. I recommend 10V 1000uF Silmic for Source resistor bypass in my circuit. Good tone.
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Old 6th September 2008, 02:32 PM   #74
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I need a good psu, dual mono, because despite
provisionally use of a smtp meanwell with 120mvp-p ripple/noise ,in my previous dac (1543) not so big difference to the ear respect battery
, as the absorption in the game are so low I can do
a with a trafo for 36-40vdc out and use the resistance drop in for
24vdc ,right?
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Old 6th September 2008, 02:54 PM   #75
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I had some boards burned for a low noise switching supply -- it's directly taken from the Linear Tech datasheet so no originality implied or warranted -- promised noise is 100uV or less -- and you can run it from the USB or a wall wart:

Clean bipolar power from USBuss

since we are getting the wrath of a hurricane I won't be out in the garden today, probably just making the SMSP transformer.
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Old 6th September 2008, 04:21 PM   #76
Salas is offline Salas  Greece
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Quote:
Originally posted by nicoch46
I need a good psu, dual mono, because despite
provisionally use of a smtp meanwell with 120mvp-p ripple/noise ,in my previous dac (1543) not so big difference to the ear respect battery
, as the absorption in the game are so low I can do
a with a trafo for 36-40vdc out and use the resistance drop in for
24vdc ,right?

If you use 36VAC it will give you about 50V DC after the bridge, on filter cap. Measure you current draw for 24V as it is now. Keep that reading. You may drop 20V on a resistance (Vdrop=I*R) to go 30V and feed a regulator set on 24V. Also Wres=Vdrop*I so to know the wattage burned on your resistor. Keep its W rating 3 times that.
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Old 6th September 2008, 06:32 PM   #77
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fine thanks !!

for trafo I can find good only at 30vac (60va),but this have no load factor 1,14 , ie 34,2 with this load do not drop too much ,if 31vac x 1,44 = 44.64 in the and I think 38vdc min for your phono
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Old 6th September 2008, 08:11 PM   #78
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HI Salas

safe?? 40V is an absolute maximum rating for 2SK170
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Old 6th September 2008, 08:16 PM   #79
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Its almost half that across the FET after the drain resistor voltage drop.
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Old 6th September 2008, 08:18 PM   #80
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