From The Daft Idea Department

[mr2racer]

Hey Anyone,

Another Kevin idea from left field... What if I were to use a single ended output transformer as a pentode push pull output transformer? I know single ended transformers have an air gap in the core to avoid saturation. But picture this. B+ is applied to the plates of a pair of output tubes driven in pentode mode. Obvious as there are no ultralinear taps. The DC path is from plate to ground. Bypassing the transformer entirely. With the primary end taps connected to each output plate. The primary will only see the ac signal so a relatively low current transformer can be used to produce more power than a standard push pull?

Kevin

 

[Miles Prower]

Google up Circlotron. This looks very similar to a description of the original Circlotron (not the mod for producing OTLs) that also used pents as pents.

 

[kevinkr]

Fun project, but you are just substituting one set of problems for another.. LOL Note that in a normal PP output transformer the net DC flux is zero (in an ideal world), so no benefit from your proposal and this would not lessen the required core area from an AC perspective.

 

[mr2racer]

The Circlotron is too complicated. I was thinking something simpler like this?

 

[iaxxaxxai]

It would probably need plate load resistors.

 

[dave slagle]

It definitely needs a plate load.... and a CCS would be a good place to start.

dave

 

[cnpope]

The Circlotron is too complicated. I was thinking something simpler like this?

You've got the primary shorted out completely; both ends connected together at B+.

Chris

 

[Miles Prower]

The Circlotron is too complicated. I was thinking something simpler like this?

That won't work at all. The output's shorted directly to AC ground. You'd need something like a center tapped choke, active CCS plate loads or gyrators and capacitor couple to the OPT to make a PP parafeed design.

It's either that, or a bridge (Circlotron type) output.

 

[Shoog]

That could only be made to work if the B+ was seperate for both pentodes and was through a CCS. The CCS needs to be able to swing the whole AC signal which means a much higher B+ (about 2x).
You have sort of reinvented parafeed.

Not really a runner.

Shoog

 

[SY]

That won't work at all. The output's shorted directly to AC ground.

Second thread like this today. Must be synchronicity.

 

[mr2racer]

Sy, synchronicity, Ala Jung would require three occurrences. And guys I didn't post anything near a complete schematic. I was just asking if you could use an SE transformer as a push pull one where DC was not present in the primary. How exactly that would be done I would need to work out. One question? Why would you need separate power supplies? Oh, and I'm looking into the parafeed.

 

[rmyauck]

Maybe not so Daft as I read of someone doing it with 2 SE trans with the primary in series per CH. and it worked really well.
Only problem was the transformers had to be perfectly matched, so was not economicallly viable as he was an amp builder.