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Thread: two half wave rectifier tubes to make a full wave rectifier?

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    two half wave rectifier tubes to make a full wave rectifier?

    I recently came into possession of a bunch of tube radios. Most of its junk but I got enough out of it to build myself a little weirdo champ copy (hoping to also build a sort of push-pull deluxe once i manage the champ), but the rectifier tubes I have (35w4) are half wave rectifiers. Would it be possible to wire them up such that they act as a full wave rectifier? Was basically going to build up this circuit, http://www.diyguitarist.com/Schemati...-Schematic.jpg but that guys lacks a power transformer. I've got a salvaged one I think I can use, but from what i understand PTs usually like to be symmetrically loaded (please pardon me if i'm talking out of my ass, this is my first attempt at such a ground up project). thanks for any help with this project!

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    i should mention that I believe my PT is center tapped.

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    Supporting Member jazbo8's Avatar
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    You could do it with two dual VT rectifiers, but one VT rectifier and a pair of silicon diodes will probably suffice - this way saves power (one less filament to deal with) and you still retain the slow turn-on, sagging characteristic of the VT rectifier.

    Jaz

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    Supporting Member loudthud's Avatar
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    The RCA tube manual rates the 35W4 peak inverse voltage (PIV) at 330V max. The heater to cathode voltage rating is plus or minus 330V. That limits output voltage to 165VDC. The octal version 35Z5 is rated at 700 PIV.

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    Don't forget the joker g1's Avatar
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    Where are you going to get 35 volts to run the heaters from? I believe those rectifiers are used in equipment with no power transformers (widow-makers).

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    "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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    thanks everyone,

    Quote Originally Posted by jazbo8 View Post
    You could do it with two dual VT rectifiers, but one VT rectifier and a pair of silicon diodes will probably suffice - this way saves power (one less filament to deal with) and you still retain the slow turn-on, sagging characteristic of the VT rectifier.

    Jaz
    excuse my ignorance, but what does VT stand for? using a pair of diodes with the tube was my initial plan until i was doing inventory and realized i had 2 of these tubes, and the name of the game with this amp is "how much of this junk can i use, regardless of impracticality"

    Quote Originally Posted by g-one View Post
    Where are you going to get 35 volts to run the heaters from? I believe those rectifiers are used in equipment with no power transformers (widow-makers).
    g-one- the heaters would be ran in series off of the secondary taps. I'll drop the voltage to about 110v with a resistor. (and 35 + 12 + 12 + 50 = 109) + 35 if i use this 2nd 35w4

    loudthud, this is my first "figure it out with parts amp", what's the relevance here? are you basically saying that it's impossible based on the specs of the tube?

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    ah, i just looked up PIV. so it seems like this power transformer I wanted to use won't work as I'd be giving it waay more voltage than it can handle. I was hoping to avoid buying a 1:1 iso transformer, but they're cheap anyway so I guess I wont sweat it, and will just got the silicon diode route.

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    actually i also have a 35z5, but i only have one so I'd still have to go the diode route- but could i avoid buying an iso transformer if i use the 35z5 rather than the 35w4?

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    Supporting Member jazbo8's Avatar
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    VT = vacuum tube ;-)

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