Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: EKDENTON on March 22, 2016, 11:35:04 am
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Here is a power supply design that was in a 1957 mechanics illustrated magazine. I was looking at the top of the capacitors...... that looks a little dangerous. and the terminal strip with the voltage out legs are exposed 450v. LOL Would this even be useful for anything?
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Not on my bench. You realize there is 1200VAC across the ends of that HT secondary? I think the circuit is wrong. No way are they knocking the B+ down to 450V as drawn. Maybe if the filter had a choke input rather than a cap input it could be a bit more useful. Still gonna be a very high B+.
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I see one thing that looks off, the line that goes to the terminal strip that is supposed to supply over 400v is connected to one side of the 5v secondary coil.
It just looks creepy dangerous with the steel terminal rings on top of the big capacitors, uncovered ...... just waiting for a little kid to say what is this? and touch the hot end.
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Mechanics Illustrated was often poor material.
It looks like 600 V DC even at 125mA load. 814V un-loaded.
Read the stuff from Tom McCahill; that's straight dope. (Interesting guy also.) Much of the rest is worth less than it cost in 1957.
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I see one thing that looks off, the line that goes to the terminal strip that is supposed to supply over 400v is connected to one side of the 5v secondary coil.
That's the way it is done with all rectifier tubes when the filament is also the cathode.
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yes I see what you mean Steve.... I had forgot how they are wired. I did put together an 18 watt light and two 5e3 amps that have tube rectifiers you would think i would remember. But that was several years ago.
PRR did he write articles in mechanix illustrated? I can't find anything written by him in this one it's February 1957. I have several others but i sent them to a thrift store. This edition has an article about how the US needs to claim the moon before the "reds" claim as their soverign territory. LOL
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The power supply at 125 mA will actually have about 450 V at the output, for 5Z3 rectifier, and choke input, the only problem is that 5Z3 is rated for 500 V rms per anode... :occasion14: