Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Effects => Topic started by: 12bz7 on February 28, 2010, 12:30:21 pm
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I'm toying with the idea of building a single tube (12ax7) FX loop from one the many schematics floating around the net. I have a single rack space chassis that's been kicking around for years which would suit this project. My problem is finding a trans small enough to fit in this chassis. I do have a small filament trans which will fit but is only rated a 500mA. My wall power is 240v so I figured perhaps 2 of these back to back would do the job. I'm thinking of tapping the heaters from the first trans' secondary, connecting the #2 trans secondary to #1 secondary which would give 240vac on #2 primary ( which is now HT secondary, if that makes sense). My questions are, Can this be done given the size of the tranformers involved?
Do I ground the CT of the 6.3v winding or use 100 ohms resistors or no grounding at all?
Has anyone tried this before on this forum?
Thanks for any help
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Well, as I understand it, you don't want them back to back (in series), as that would double your voltage without improving your available current. You would want them in parallel, which would keep the same voltage, but spread the load across both transformers.
THIS (http://sound.westhost.com/xfmr2.htm#8.series-parallel) should help you understand it. Make sure you get your phase right, and that they really are a good voltage match. I like the line in the link about either melting a transformer or blowing a fuse, with the latter usually being preferred. :violent4:
Gabriel
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Thanks Gabriel for the Link, I will have to study it for a while before I attempt anything.
Seems like there's a lot of good information on that site
thanks again
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I've drawn up a little schematic to make it clearer, perhaps someone has tried this before with success.