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When designing a tube rectifier circuit do you have to use a center tapped PT? I thought I saw one somewhere that did not have a CT but all I can find now have a CT PT. Thanks
Tube rectifier circuits
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Re: Tube rectifier circuits
You need a centre-tapped PT, three rectifiers (plus individual heater windings), or one rectifier and two diodes.
If you visualise a full-wave bridge with the AC top and bottom then on one side you have two diode cathodes tied together and on the other side you have two anodes tied together. You could use a rectifier tube for the common cathode side and diodes for the common anode side.
All of the current has to flow through the rectifier tube so you should still get the sag/feel of the tube.
If you visualise a full-wave bridge with the AC top and bottom then on one side you have two diode cathodes tied together and on the other side you have two anodes tied together. You could use a rectifier tube for the common cathode side and diodes for the common anode side.
All of the current has to flow through the rectifier tube so you should still get the sag/feel of the tube.
Re: Tube rectifier circuits
Huh???
For example look at any of the old Fender schematics using the 5Y3GT tube there are no SS diodes in there. But they do use a center tapped PT. My question is do you have to use a ct pt if you want to use a 5Y3GT? Thanks
For example look at any of the old Fender schematics using the 5Y3GT tube there are no SS diodes in there. But they do use a center tapped PT. My question is do you have to use a ct pt if you want to use a 5Y3GT? Thanks
Re: Tube rectifier circuits
mcrracer,
Are you talking about CT on secondary voltage or CT on 6.3 taps?
It is common not to have a CT for the 6.3 filament so you use a 47ohm resister on each 6.3v leg to ground then to each filament on the tubes.
As for no CT on the HV secondary use 100ohm 1W resistor each leg to rectifier tube. Look at Hiwatt DR103 if going with using diodes.
Mark
Are you talking about CT on secondary voltage or CT on 6.3 taps?
It is common not to have a CT for the 6.3 filament so you use a 47ohm resister on each 6.3v leg to ground then to each filament on the tubes.
As for no CT on the HV secondary use 100ohm 1W resistor each leg to rectifier tube. Look at Hiwatt DR103 if going with using diodes.
Mark
Re: Tube rectifier circuits
Option 1 in my reply should have read a centre-tapped transformer <i>and</i> a single rectifier.
If you want to use a transformer without a centre tap then you have options 2 and 3.
You could try to create a faux centre-tap using resistors but all current drawn would have to pass through these resistors.
If you want to use a transformer without a centre tap then you have options 2 and 3.
You could try to create a faux centre-tap using resistors but all current drawn would have to pass through these resistors.
Re: Tube rectifier circuits
Sorry , I wasn't clear. Center tapped high voltage secondary. I will take a look at the referenced circuit.M Fowler wrote:mcrracer,
Are you talking about CT on secondary voltage or CT on 6.3 taps?
It is common not to have a CT for the 6.3 filament so you use a 47ohm resister on each 6.3v leg to ground then to each filament on the tubes.
As for no CT on the HV secondary use 100ohm 1W resistor each leg to rectifier tube. Look at Hiwatt DR103 if going with using diodes.
Mark
Re: Tube rectifier circuits
I just looked at that power supply schematic and I do not see a rectifier tube at all. Take a look at a Fender Schematic which uses a 5Y3 tube. There are no SS diodes in those circuits. just a tube. The Deluxe 5C3 for example.M Fowler wrote:mcrracer,
Are you talking about CT on secondary voltage or CT on 6.3 taps?
It is common not to have a CT for the 6.3 filament so you use a 47ohm resister on each 6.3v leg to ground then to each filament on the tubes.
As for no CT on the HV secondary use 100ohm 1W resistor each leg to rectifier tube. Look at Hiwatt DR103 if going with using diodes.
Mark
Re: Tube rectifier circuits
What's the question? For a tube-rectified circuit, e.g. the 5C3, you only have two (tube) diodes in the rectifier sharing a common cathode, so you have to use a centre-tap, which is your ground for the DC side. At any point in time one half of the HT secondary is conducting with the current flow between this side of the winding and the centre-tap. On the other half of the cycle the other side picks up.
If you want to use diodes then you have a choice of wiring it as a full-wave rectifier the same as the tube using two diodes (e.g. an Express, which uses two diodes in series to get the voltage rating) if you have a centre-tap or a full-wave bridge rectifier, like a Marshall 100W Superlead which doesn't require a centre-tap.
This requires two diodes with the anodes tied together though, which you can't get in a tube. That's why I said you can get a half-way house by using two diodes as the common-anode side of a full-wave bridge and the tube as the common-cathode side if you don't have a centre-tap and are adamant that you want to use tube rectification.
If you want to use diodes then you have a choice of wiring it as a full-wave rectifier the same as the tube using two diodes (e.g. an Express, which uses two diodes in series to get the voltage rating) if you have a centre-tap or a full-wave bridge rectifier, like a Marshall 100W Superlead which doesn't require a centre-tap.
This requires two diodes with the anodes tied together though, which you can't get in a tube. That's why I said you can get a half-way house by using two diodes as the common-anode side of a full-wave bridge and the tube as the common-cathode side if you don't have a centre-tap and are adamant that you want to use tube rectification.