Transformer multi 0v center taps?

[Ekometti]

Hey guys, I am pretty new to building and have had this question haunting me for awhile now. I look at various layouts and see the amp using a Pt with multiple 0v CT leads (that's what it looks like anyway) but none of the transformers I have found have them, ie Hammond or classic tone. Am I missing something? Can I just run several leads off of the single CT?

Thanks in advance
Erik

[Reeltarded]

An example would be helpful!

Are you looking at amps with false CTs?

[JoeCon]

Hi Erik

I'm pretty new at this too but I think what you are seeing are the different CT's for the different sections of the PT.

For supply power you'll have a 300-0-300 and for heaters a 3.15-0-3.15 so both of those sections of the PT have a seperate CT.

So depending on which section you're using that CT goes with that section.
Looking at the xformer data sheet helps too as they show a diagram of it.

[martin manning]

All PT's designed for a full-wave rectifier will have a CT on the high voltage secondary. A full-wave bridge rectifier design does not use a CT. Many will have a CT on the 6.3VAC filament winding, but not all. If there is no CT on the 6.3VAC winding, an artificial CT is created by connecting a 100-150 ohm resistor from each end of the winding to ground (or to a DC voltage if the filament circuit is elevated). Some PT's will have an internal shield with a lead attached that is to be grounded. This Bassman PT has two CT's and a shield: http://www.classictone.net/40-18073.pdf More wires from the same tap would only be a waste of wire.

[JoeCon]

So Martin

For B+ it's the Red -Red/Yellow(CT)-Red (#3-5-6) with the Red/Green providing 50V for bias.

Thanks.

[martin manning]

Correct. The bias circuit has a very low current requirement so ading an extra tap on one side of the HT winding works. In some cases the bias supply has it's own separate winding.

[Ekometti]

I'll attach a picture of a PT with multiple cts. What would the solution be if I cannot obtain one especially if the layout / schematic call for its use? Ceriatone ots and brown note use a PT with multiple ct taps.

[JazzGuitarGimp]

Not every zero is a CT. For instance, the bias winding (the two yellow wires) has no center tap. If it did, you'd see a third wire of a different color egressing from between the two yellow wires, and their labels would be 30 (yellow) - 0 (other color) - 30 (yellow). And then '0' would be the center tap because it is 'centered' between the two 30V taps. You still get 60V from one '30' tap to the other '30' tap (yellow to yellow). Does this help?

[Ekometti]

So the labeling on the PT is misleading?

[JazzGuitarGimp]

So the labeling on the PT is misleading?

No it isn't. The bias winding, as labeled tells you that you have 60VAC between the two yellow wires, with no center tap.

If you look at the 6.3V heater winding, you'll notice three wires, labeled as follows: 3.15V - 0V - 3.15V. What this tells you is that you have 6.3V between the two wires labeled 3.15V, and each of these two wires have equal voltage (but opposite phase) with respect to the 0V center tap.

[Ekometti]

Ok, so now the question is aside from the 18073 from classic tone who else provides these types of transformers, 325-0-325 3.15-0-3.15 120-0-120 and 50-0 so I would have the 4 ct that seem to be required.

[Ekometti]

I also found this invoice floating around. Would this be an option for what I am looking for?

[JoeCon]

Erik

I guess we need to know more about what you ARE looking for. Schematic?

That PT has outputs for 325-0-325 for your B+ supply, looks like 45 V for bias, and 3.15-0-3.15 for heaters with 5 volts for tube rectifier.So it looks like the yellow, the green/yellow and the red/yellow would all go to ground.

The red/yellow and green/yellow are center taps. In the diagram they come out in the CENTER of the winding. Thus a center tap off that winding.

Clear as mud? LOL...

[Ekometti]

I've been working on a ceriatone ots 50w and have finished everything but the PT and heater connections. I ordered a classic tone 18073 and it is short the number of ct connections that are needed. How can I remedy this?

[Colossal]

I ordered a classic tone 18073 and it is shot the number of ct connections that are needed. How can I remedy this?

Post the drawing of the 18073 part as drawn by ClassicTone. For instance, if you substitute a 6.3VAC-0 winding for a 3.15-0-3.15 heater winding, you may want to create an artificial center tap or use a "humdinger" CT arrangement.