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Audio and Video Talk
Valves / Vacuum Tubes
How to design a Power Transformer for a Push-pull tube amplifier?
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<blockquote data-quote="BarryD" data-source="post: 196039" data-attributes="member: 13633"><p>@handsome - Your points on resistors are noted. I have been finding out some of this stuff for myself, albeit slowly, and over a period of time! Sometimes wish my Dad was still around - he built a Williamson in 1949, and was a telecoms engineer by trade, he knew all about valve circuitry. I have his RSGB handbook from 1943, that has been a mine of information. With us, going back to a prior technology, there is bound to be a learning curve! Fun though, thats what hobbies are for. For me, still much more rewarding to build something, than cruise down to a dealer and buy a box.</p><p>Another issue here is air flow - didn't bother much with S/S equipment, just put power devices on heatsinks on the outside. Now I have hot resistors on the underside of the chassis, there has to be a path for air to flow through.</p><p> </p><p>@Ampdog - Thanks for you input. Power supply is probably overkill, that was because of experience with the prototype. My original design was much more of an overkill, but luckily I circulated it by email to a couple of enthusiasts (before I found this forum). One memorable Saturday, it went round in circles about 10 times, shedding components at every iteration. Eventually, about midnight it was decided that the thing was OK, and that is what I built, with a few minor alterations. I share your reservations about the LC after the regulator - that is getting precariously close to a relaxation oscillator, see this data sheet;</p><p> </p><p><a href="http://www.r-type.org/pdfs/gl874.pdf" target="_blank">http://www.r-type.org/pdfs/gl874.pdf</a></p><p> </p><p>Total preamp draw is 10.4mA, not too much of an overload there. Cf my Williamsons, 120mA @ 450V, and an 8uF cap. No trace of hum!</p><p>Out of curiosity, I will take out the LC after the regulator on one channel, and just see what happens. The extra 15V won't matter.</p><p>Nice thing about valve circuits is one can do this sort of thing in about 1 minute!</p></blockquote><p></p>
[QUOTE="BarryD, post: 196039, member: 13633"] @handsome - Your points on resistors are noted. I have been finding out some of this stuff for myself, albeit slowly, and over a period of time! Sometimes wish my Dad was still around - he built a Williamson in 1949, and was a telecoms engineer by trade, he knew all about valve circuitry. I have his RSGB handbook from 1943, that has been a mine of information. With us, going back to a prior technology, there is bound to be a learning curve! Fun though, thats what hobbies are for. For me, still much more rewarding to build something, than cruise down to a dealer and buy a box. Another issue here is air flow - didn't bother much with S/S equipment, just put power devices on heatsinks on the outside. Now I have hot resistors on the underside of the chassis, there has to be a path for air to flow through. @Ampdog - Thanks for you input. Power supply is probably overkill, that was because of experience with the prototype. My original design was much more of an overkill, but luckily I circulated it by email to a couple of enthusiasts (before I found this forum). One memorable Saturday, it went round in circles about 10 times, shedding components at every iteration. Eventually, about midnight it was decided that the thing was OK, and that is what I built, with a few minor alterations. I share your reservations about the LC after the regulator - that is getting precariously close to a relaxation oscillator, see this data sheet; [url=http://www.r-type.org/pdfs/gl874.pdf]http://www.r-type.org/pdfs/gl874.pdf[/url] Total preamp draw is 10.4mA, not too much of an overload there. Cf my Williamsons, 120mA @ 450V, and an 8uF cap. No trace of hum! Out of curiosity, I will take out the LC after the regulator on one channel, and just see what happens. The extra 15V won't matter. Nice thing about valve circuits is one can do this sort of thing in about 1 minute! [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
How to design a Power Transformer for a Push-pull tube amplifier?
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