Strange little circuit

[carpenter]

Hi guys. I'm simming this little circuit, which seems to work in the virtual world, but haven't seen it the the real world.

Resistor 25 is the only way I can get this thing to make an amplified signal. Seems that the load on the mosfets is just about perfect, according to the sim's power/voltage graph.

Normally, I took the output from the mosfet drains (which were connected to + with a pair of 330 ohm resistors) to the transformer and just left the primary center tap alone.

This is kind of a backwards way of doing the same thing, or is it? Changing the value of R25 has a dramatic affect on gain.

Any comments?

[Nelson Pass]

It looks workable to me, but there might be an issue with
your transformer model.

[carpenter]

Originally Posted by Nelson Pass

It looks workable to me, but there might be an issue with
your transformer model.

With Simetrix, I simmed an "ideal" transformer (which doesn't really exist). The primaries are 10H each. The step up is 4 to 1. I noticed that for the same overall gain, the step up takes a lot of load off the mosfets; their power curves are more uniform. Still, I can't help but wonder if the transformer creates more distortion than it cures--guess I'll have to locate an interstage transformer and find out.

[Zen Mod]

I just finished this weekend one drek CD player , worth 1k7E ;
Beyerdynamic microphone xformers instead zillion OP's in I/V conversion and lowpass ;
that's pure music now .

even if that's distortion , I like it ; my friend ( who is owner ) is happy camper now .

[carpenter]

Originally Posted by Zen Mod

I just finished this weekend one drek CD player , worth 1k7E ;
Beyerdynamic microphone xformers instead zillion OP's in I/V conversion and lowpass ;
that's pure music now .

even if that's distortion , I like it ; my friend ( who is owner ) is happy camper now .

Sounds interesting, Choky. I'm trying to locate some decent interstage transformers for this project. Perhaps you could guide me? I've noticed that the bandwidth is a bit limited on many models in the catalog (the internet ) I put a bug in Tom's ear down at Hammond... maybe they can stir me up a custom gadget.

According to the sim, the current is very low, less than 100uA, so that should help with size, because it needs lots of inductance--on the order of 10H to 30H in the primaries, and lord only know what that does to the secondaries, because I want to try a step-up device.

Lots of fun...

[Manu]

Originally Posted by Zen Mod

I just finished this weekend one drek CD player , worth 1k7E ;
Beyerdynamic microphone xformers instead zillion OP's in I/V conversion and lowpass ;
that's pure music now .

even if that's distortion , I like it ; my friend ( who is owner ) is happy camper now .

We wan't to see pics ...

Manu

[Zen Mod]

even if offtopic

Primare CD31 Zen Transformation - DIYAudio.rs

Dokoni Prestoni?ani u poseti srcu Drevne Ba?ke - DIYAudio.rs

you'll see usual suspects , including Albi ,Papa ,p18 , Juma , Spavleski , Mighty ZM

Woodie - regarding IT - I'm really not familiar right now with your side of market;
anyway - you know what to chase - L of primary , ratio ,, lowest Rdc of both primary and secondary

don't be afraid of current through primary - as long LTP is DC balanced .

[Manu]

Originally Posted by Zen Mod

even if offtopic

Primare CD31 Zen Transformation - DIYAudio.rs

Dokoni Prestoni?ani u poseti srcu Drevne Ba?ke - DIYAudio.rs
.

Thanks for splendid pics, ZM ... Tasty work ...

Sorry woody for OT ...

Manu