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Old 2nd October 2013, 04:12 PM   #10191
Siberia is offline Siberia  Lithuania
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Maybe that is where we should use the kmultiplier.....
Ricardo, sorry for OT. What are the loading values that you use for the Benz cart?
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Old 2nd October 2013, 04:41 PM   #10192
Salas is offline Salas  Greece
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Quote:
Originally Posted by RCruz View Post
Maybe that is where we should use the kmultiplier.....
I think it should be used near the DC inputs after the umbilical or somewhere along its way than locally in the raw PSU as you did. As I had recommended initially. There it could filter more EMI/RFI stuff that comes along to the regulators.
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Old 2nd October 2013, 04:51 PM   #10193
RCruz is offline RCruz  Switzerland
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Originally Posted by Salas View Post
I think it should be used near the DC inputs after the umbilical or somewhere along its way than locally in the raw PSU as you did. As I had recommended initially. There it could filter more EMI/RFI stuff that comes along to the regulators.
Indeed, it works much better placed after the smoothing caps and away from the psu
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Old 2nd October 2013, 04:52 PM   #10194
RCruz is offline RCruz  Switzerland
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Originally Posted by Siberia View Post
Ricardo, sorry for OT. What are the loading values that you use for the Benz cart?
Between 2000 and 3000 ohms... system dependent
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Old 18th October 2013, 12:13 PM   #10195
Marra is offline Marra  United Kingdom
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I rigged up my power supply this morning using an R core transformer with secondaries [18v] connected in series the capacitor with the 2x10k resistors and an led the resultant dcv was 56.4.Is this going to be ok?
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Old 18th October 2013, 12:18 PM   #10196
Salas is offline Salas  Greece
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That's too much. I got 45-47VDC. Does it say 220VAC on the label and you got 240VAC?
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Old 18th October 2013, 12:21 PM   #10197
Marra is offline Marra  United Kingdom
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Its a Selectronic R core 230VAC.Where I live the mains voltage rarely ever drops below 240v and quite often sits at 245v.I didn't check this morning.
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Old 18th October 2013, 12:33 PM   #10198
Salas is offline Salas  Greece
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So you use the bleeders too and it behaves too high still. Weird, I use R core too. Even at x1.4 it should hit 50VDC if it was 36VAC. Can you measure the secondary in AC?
Its not that the input sink will not take the 20V drop, its lukewarm with 10V drop, but I am afraid of you frying Q2X in the reg because its going to see VDCin-3LEDS across. Its a 50V spec FET the K117 and it will be right on max VDS edge plus dissipating more. It can be fixed by some resistor in series with the secondary, but better get the 2X15 Selectronic R core when in the UK or Australia it looks like.
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Old 18th October 2013, 01:33 PM   #10199
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I used E-I core transformer :
230V primary
2X36VAC secondary
after plugging the PSU circuit - I am getting ~48VDC for each channel which I guess is fine
-(sqrt2 x 36VAC).

54VDC sounds too much.
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Old 18th October 2013, 01:38 PM   #10200
Salas is offline Salas  Greece
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Yours looks normal. That R core surely overshoots spec and gets even higher on UK mains.

P.S. Times 1.33 the measured secondary VAC should be about right for the raw DC expected including losses at the voltage level and VA we use here.
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