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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Re: DIY Tube amp current posted by Sherwood on May 19, 1999 at 15:53:34:
I agree with what Sherwood says here.To refine the thoughts a little bit perhaps -
You can use a trans with a much higher current rating, but a power trans is usually designed with a certain degree of self regulation in mind, around it's rated current. If you go in the direction of overkill and get a way huge trannie for the job, you will loose a little of that inherent voltage regulation. A minor point, but worth considering if you really want to fine tune circuit.
Also, you can indeed scrub off excess B+ pretty easily, but bear in mind that using resistance to do this adds to your power supply impedance. Sometimes switching from a cap input to a choke input filter can get you closer to a needed B+ with the types of trannies you may have available to you.With SS full wave rectification you can pretty much use the standard formulae of B+= .9 times the 1/2 the secondary voltage for choke input and 1.4 times 1/2 the secondary voltage for cap input.
If you decide to use a tube rectifier, use a tube manual to give you an idea of where your voltage will end up - every rectifier type has a different impedance.Gordon Rankin's trick of using a small input cap on a choke input filter is an interesting way to hit voltages between those .9 and 1.4 X numbers without resorting to voltage dividers.
Don't forget to account for the voltage drop through your filter choke(s)
And a final thought - a way cool way to use up excess V and I is to implement a shunt regulator.
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Follow Ups
- Re: DIY Tube amp current - Doc B. 17:35:00 05/19/99 (1)
- Re: DIY Tube amp current - ChristopherC 07:02:59 05/20/99 (0)
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