The V-Fetron Comes To Life

[dantwomey]

I'm intrigued by Michael's latest design. My first thought when I saw the schematic was if it would be as easy to make it a balanced input as it was with the IronAmp.

Regards,
Dan 🙂

 

[WBS]

Eureka!

This looks like an interesting use of a couple of the 2sj28 that I bought last fall. I bought 6 after the pairs sold out and just ordered 4 more since the sj28s are almost all gone!

I just need someone to fill in the values to the simplified schematic 'cause I ain't no math whiz. 😕

 

[nicoch58]

😀😀

 

[wdecho]

This looks like an interesting use of a couple of the 2sj28 that I bought last fall. I bought 6 after the pairs sold out and just ordered 4 more since the sj28s are almost all gone!

I just need someone to fill in the values to the simplified schematic 'cause I ain't no math whiz. 😕

Nelson has promised one of his circuits using this transistors. I picked up some too with anticipation of his one day finding time to design an amp using these transistors. If you reverse the voltages you can use it in one of Michael's designs using transformers.

 

[kevinkr]

Thread cleaned up. I recommend everyone play nicely going forward.

 

[dantwomey]

This looks like an interesting use of a couple of the 2sj28 that I bought last fall. I bought 6 after the pairs sold out and just ordered 4 more since the sj28s are almost all gone!

I just need someone to fill in the values to the simplified schematic 'cause I ain't no math whiz. 😕

No worries, I'm sure we'll have a more detailed schematic once all the testing is done. BTW I built the IronAmp that Michael designed and it was so good it just worsened my addiction to amp building. 😉

Regards,
Dan

 

[hifibluedevil]

Just ordered a quad of 2sj28s from famous place down in Singapore. I dig this circlotron design.

 

[aspringv]

@hifibluedevil Mind if I ask where on Singapore? I'm considering getting a few myself with a view to this build. 🙂

 

[hifibluedevil]

@hifibluedevil Mind if I ask where on Singapore? I'm considering getting a few myself with a view to this build. 🙂

here:
2SJ28 P Channel VFET From Sony

 

[aspringv]

Thanks! I may as well grab a few...

Cheers!

 

[aspringv]

....and V-Fets ordered. Now to find out what sort of transformers were used... 😉

 

[aspringv]

reg'd psu's

So I'm slowly jimmying up some pcb's here. Anyone got a great suggestion for the bulk power supplys? reg'd? and if so, how? Thoughts currently are a basic reg (ala cx1 vfet pass psu) but open to suggestion!

 

[Michael Rothacher]

It's entirely down to taste, but for anyone who's looking for a head start on this project (sorry I'm out of commission) you can pretty much copy and paste the various supplies from the VFET Part 1 article by Nelson Pass. Scaled up for the 75 watter of course. 🙂

 

[aspringv]

Hi Mike,

Any chance you've a value for those resistors I see in the schematic?

Cheers in advance 🙂

PS - I guess your website is down due to the move. I hope it all goes well!

 

[Michael Rothacher]

100R or so.

🙂

 

[aspringv]

Cheers!

I'm getting along with the build. Brackets are the current wait, but most everything else is collected/ready to go. I've not ordered the Jensen's yet though. I have to confess to trying to find cheaper/local solutions...

 

[aspringv]

With this being the likely front runner...

http://www.altronics.com.au/p/m0707-600-ohm-600-ohm-shielded-bridging-transformer/

 

[nicoch58]

humm only 20Hz - 13kHz

 

[aspringv]

You should have seen the alternatives! It's enough to get me started...

 

[aspringv]

Actually - any insight on testing? I intend to hook the transfo up to a PC and analyse it coupling input to out put...