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Old 30th January 2009, 01:41 PM   #841
iko is offline iko  Canada
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Quote:
Originally posted by nicoch46

>disconnect the main heart , if is this put two diode reversed with ntc like Pass

Sorry, I don't understand this suggestion. Could you please explain?
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Old 30th January 2009, 01:47 PM   #842
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Quote:
Originally posted by salas


Is it something that came up after the initial tests? A buzzz indicates 100Hz. See the psu output on the scope. If it still works OK with a clean output, its a ground loop, or a transformer field. Batteries are essentially floating devices.
It was probably there, but I usually don't pay attention to such things in the beginning. The scope shows a spike about 10mV/div high on the PSU output, but I didn't check the frequency. The transformer was quite far from the regulator and preamp, far enough for it's field not to affect anything, I think. I suspect the psu as the main culprit, or a ground loop/problem.
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Old 30th January 2009, 02:09 PM   #843
Salas is online now Salas  Greece
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This PSU does not pass 100Hz ripple for sure by design. Many have been built and work for months now. There must be some error somewhere if it does so.
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Old 30th January 2009, 02:18 PM   #844
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Quote:
Originally posted by salas
This PSU does not pass 100Hz ripple for sure by design. Many have been built and work for months now. There must be some error somewhere if it does so.
Do you mean the regulator?
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Old 30th January 2009, 02:19 PM   #845
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Quote:
Originally posted by ikoflexer
or a ground loop/problem.
If you will not find 100Hz on the PSU's output (which may be fortunate if there is just a small error to fix), case of having some ground loop is a bad situation to solve some times. I hope not. What about your TT ground wire? Is it grounded OK?
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Old 30th January 2009, 02:21 PM   #846
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Quote:
Originally posted by ikoflexer


Do you mean the regulator?
Yes. I mean PSU as a whole, including the regulator. You refer to just the raw PSU before the reg?
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Old 30th January 2009, 04:00 PM   #847
Salas is online now Salas  Greece
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Quote:
Originally posted by ikoflexer



Sorry, I don't understand this suggestion. Could you please explain?
He probably means to float the mains earth and use a couple of mutually reversed parallel diodes that will open up in case of emergency and restore earthing. If I got this right, Nicoch will present me a master's in Nicochian linguistics.
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Old 30th January 2009, 04:00 PM   #848
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Yes, the TT ground cable was properly connected. I still tried different connections for it, but no change.

I was referring to the trafo+bridge+CLC filter as the psu, just to keep it separated logically from the regulator. Surely it's something stupid I've done, I'll check things again tonight.

What I don't understand from what you said salas, is, do you mean that even if there is ripple going into the regulator, the regulator should flatten it out? It certainly behaves so in simulation...
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Old 30th January 2009, 04:04 PM   #849
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Quote:
Originally posted by ikoflexer



Sorry, I don't understand this suggestion. Could you please explain?
disconnect the main earth sorry I don't speak english
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Old 30th January 2009, 04:08 PM   #850
Salas is online now Salas  Greece
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Quote:
Originally posted by ikoflexer
What I don't understand from what you said salas, is, do you mean that even if there is ripple going into the regulator, the regulator should flatten it out? It certainly behaves so in simulation...
Yes it will cut out any input ripple with its negative comfortably above the VGS threshold of Q1. Imagine the CCS as an extremely large choke that isn't storing energy. See here post#157, for a practical test report.
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