I would guess that what you are seeing is a leakage reactance issue. This often happens with OTs with multiple output Z taps. These 10 Lb'r things aren't interleaved like an OT, so the windings have significant leakage reactances to each other. (see my measurements above) When the 6.3 VAC winding gets loaded down, some of the mag. flux is avoiding going thru the 6.3 V winding by leaking around thru the HV winding. Since there is no load on the HV winding, its voltage jumps up. (well, I could have the explanation backwards too, the HV winding's leakage reactance may be shorted out by the load on the 6.3 V winding, same result) Probably just a little load on the HV will cause it to drop back down by pushing the extra flux back into the core. Might get slightly different results from loading different 6.3 V windings too.
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I just tried loading the three 6.3 V windings (one at a time) on a boat anchor here and they all lower the HV slightly. So must be something else. Maybe a spike in the waveform? Diode commutation ringing?
Note: I have both primaries connected in parallel. Could be different results if running on just one.
...................Just tried the primaries individually, and same results. Your xfmr is wacko, or some spike effect from the diode bridge, or operator error............
Note: I have both primaries connected in parallel. Could be different results if running on just one.
...................Just tried the primaries individually, and same results. Your xfmr is wacko, or some spike effect from the diode bridge, or operator error............
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Dumb question since i have an extra and dont know what to do with it. Is it possible to get 400-450vcd (the other popular b+)? These things put out what, 225vac right, so could i use a voltage doubler (still have no clue how to design one with the correct values) to get the thing to 450ish vac, then have a 5H choke right after so it would be 450vdc? Or does the doubler cap load it and im stuck with 600ish b+ no mater what?
I think you are stuck with the 600 V in doubler mode. Could try some simulations using two inductors, one for each cap input path. Probably get very poor V regulation that way. Putting the inductor in the common lead to the caps will lower the voltage, but that will have poor regulation too, since it is passing AC and not DC there.
As an extreme measure, could try putting an inductor/cap series combo in series with the primary, resonant at 60 Hz, and with low enough Z at 60 Hz to support the current draw (needs to have circulating current in the resonator greater than the avg load current I think). Then a voltage doubler on the secondary. This will give approx 2X *.9 the average voltage I think. Definitely need to simulate that one though (with expected load). Any freq. change from 60 Hz will thow it off though. The resonator cap will likely have to be composed of several cap sizes in parallel to get the exact capacitance for 60 Hz resonance. Another problem is that a lot of utility power does not look like a sine wave these days (flat topped) due to all the elctronic load stuff on the line using cheapo cap input filters. (PCs, ....)
As an extreme measure, could try putting an inductor/cap series combo in series with the primary, resonant at 60 Hz, and with low enough Z at 60 Hz to support the current draw (needs to have circulating current in the resonator greater than the avg load current I think). Then a voltage doubler on the secondary. This will give approx 2X *.9 the average voltage I think. Definitely need to simulate that one though (with expected load). Any freq. change from 60 Hz will thow it off though. The resonator cap will likely have to be composed of several cap sizes in parallel to get the exact capacitance for 60 Hz resonance. Another problem is that a lot of utility power does not look like a sine wave these days (flat topped) due to all the elctronic load stuff on the line using cheapo cap input filters. (PCs, ....)
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http://www.diyaudio.com/forums/atta...0664d1292208207-10-pounds-power-15-supply.gif
Maybe I'm doing something strange with power factor correction, what I was thinking...
Then I see my old notes to the side, 667V ??? So, I may have misremembered 650V?
Doubler has only gone up 8V, probably within margin of error for line voltage and shape.
Not like those measurements were taken back to back on the same day.
Maybe I'm doing something strange with power factor correction, what I was thinking...
Then I see my old notes to the side, 667V ??? So, I may have misremembered 650V?
Doubler has only gone up 8V, probably within margin of error for line voltage and shape.
Not like those measurements were taken back to back on the same day.
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