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Need Some Help With a DC Heater Supply Rectifier Current Rating.
Need Some Help With a DC Heater Supply Rectifier Current Rating.
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Old 7th November 2017, 09:44 PM   #11
PRR is offline PRR  United States
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Quote:
Originally Posted by dotneck335 View Post
DC-elevating the heater supply is probably be more effective at reducing hum than rectifying/regulating it.
FWIW: 100V elevation was mentioned.

These address different causes of hum.

Thermionic emission happens heater-cathode, worse on some tubes. Making heater positive reverse-biases the effect and reduces the need to select tubes.

Running 6V of low audio next to milliVolt signals is just begging for trouble from electric fields between heater and signal points. DC heat logically makes wiring much less critical. Paradoxically, poorly-filtered "DC" with buzz harmonics far into the midrange may be worse than pure clean AC heat.

DC supplies need fat diodes, fat caps, and much more transformer VA than simple AC heat.
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Old 7th November 2017, 09:48 PM   #12
PRR is offline PRR  United States
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Originally Posted by DF96 View Post
Am I imagining things, or has something switched the font used in threads to a sans-serif a few minutes ago? The font used in post 9 now appears everywhere. Did JeffYoung switch something on but forget to switch it off again?
Font looks same as ever. See attached. I think it has always been a sans-serif??

Font is probably set by a Style Sheet. Sometimes the server forgets to send it to you. When all style sheets are dropped this forum looks VERY different. However a partial loss of style info might give a munged font.
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Old 8th November 2017, 02:54 AM   #13
crazyfrog is offline crazyfrog  Canada
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Need Some Help With a DC Heater Supply Rectifier Current Rating.
Default DC regulator

Get a decent regulator like Pete Millett shows on his website. The IC used is a LT1084, good for 5A.
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Old 8th November 2017, 09:24 AM   #14
DF96 is offline DF96  England
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Quote:
Originally Posted by PRR
Font looks same as ever. See attached. I think it has always been a sans-serif??
All looks normal again today. Still not sure what happened, but what I seem to recall is that post 9 had a different font (slightly larger?) which then seemed to appear on all threads I then looked at - not only on here but also another forum which uses the same software. Maybe I just had a brain fart?

Going back to the thread topic, in most cases decent AC wiring is less trouble for newbies than DC heaters - but some of them are never convinced.
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