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-   -   10m45s cascode diagram? (http://www.diyaudio.com/forums/tubes-valves/206847-10m45s-cascode-diagram.html)

mctavish 16th February 2012 09:44 AM

10m45s cascode diagram?
 
Yes, I have searched but not found what I was looking for...

Can anyone point me to a diagram for dummies on how to wire a pair of 10m45s in a cascode? I am currently using the singly in my SE amp but would like to try cascoding.

Thanks!!

euro21 16th February 2012 12:51 PM

Cascoded
 
1 Attachment(s)
Voila!

Ken Newton 16th February 2012 01:09 PM

Quote:

Originally Posted by euro21 (Post 2909083)
Voila!

I like that circuit configuration all around. :)

Magz 16th February 2012 01:24 PM

I think I'd put CCS fed gas regulator tubes on each channel instead of sharing them between channels to ensure against cross-talk, but I'm a bit prone to overkill.

Ken Newton 16th February 2012 02:32 PM

Quote:

Originally Posted by Magz (Post 2909121)
I think I'd put CCS fed gas regulator tubes on each channel instead of sharing them between channels to ensure against cross-talk, but I'm a bit prone to overkill.

Probably not needed, the cascaded CCS should provide excellent PSRR for each 12B4A stage.

zigzagflux 16th February 2012 02:54 PM

1 Attachment(s)
If you need more than 75 mA (power supply shunt regulators), this paralleled version works very well. There is benefit to having the 10M45 on top, as the DN2540 typically has a lower gate voltage for a given current. The more voltage you can provide for the bottom device the better off you are.

I place the 10M45 on the same heatsink, back to back on either side. The drains are at the same potential anyway, so no isolation requirements. I have also moved the zeners to the other side of the gate stopper, contrary to what is shown in the drawing.

mctavish 16th February 2012 02:56 PM

Thanks Euro21! Do the 10m45s have the same symbols for G, S, and D as a depletion mode mosfet?

When it comes to sand I am a bit new!

Michael Koster 16th February 2012 03:18 PM

Quote:

Originally Posted by mctavish (Post 2909219)
Thanks Euro21! Do the 10m45s have the same symbols for G, S, and D as a depletion mode mosfet?

When it comes to sand I am a bit new!

The IXYS datasheet calls the terminals G,A,K which correspond to G,D,S i.e. G=Gate
A=Drain
K=Source

The TO-220 pinout is interchangeable with other depletion mode MOSFETs e.g. the Supertex DN2540

50AE 5th December 2012 07:34 AM

Hi and sorry for the revival of an old thread.

I cannot get my cascoded 10M45S to work. The problem is, whatever the resistor value I put (80-300R), the current stays nearly the same (5-6mA). The circuit is used as CCS for a D3A tube and the target is 25-30mA.

Probably I could have screwed something by putting the two packages on the same heat sink without insulation (drain to drain)? When I did so, the current was quite high (50mA) and uncontrollable by the resistor value. Now when I isolated the 10m45s s, the current dropped to 5-6mA and is still uncontrollable by the current value resistor.

I use 1k for grid stoppers.

SY 5th December 2012 08:50 AM

Replace the FETs (they're cheap) and double check your wiring.


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