Simplistic MosFET HV Shunt Regs

A cascoded tube control element with VR tube voltage reference and EL84 pass element. Italian circuit non the less. Should have had a good tone. But those schemes although fine, can not have the noise and Zo performance and flatness that we achieve here with bunch of few parts, much more economically so, without heaters, tube wear, etc.

it works and sound good but with some problems, first with the gas tube, then the layout (it oscillates) then it is noiser than your shunt :mad:
 
Hello Salas,
A few days ago we traded a couple of posts about IXCY 10M45’s and voltage regulators over on another thread. I thought that I would drop by and slip a foot into the conversation.
All voltage regulators are voltage dividers. Series regulators control the top resistance. Shunt regulators control the bottom one. After checking it out this is the part that floors me, Shunt Regulators routinely shunt several times the connected load to ground. No wonder there is reduced over shoot and ringing and trash on the B+ due to control devices. They do not have to work nearly as hard stopping and starting.
I was thinking similar thoughts when I designed a tube headphone power triode to idle at 150 volts and 50 ma when only 0.010 watts output is needed. I suppose the word shunt applies here as well.
DT
All just for fun!
 
The circuit above has been checked enough, its stable, and it can go over 300V if the MJE350 is substituted with a proper PNP driver transistor like the 400V MPSA94 etc. R3 should be 82K & R4 220K in an over 300V application. The MJE is better if you target lower than 300V. The higher resistive load (R5) on the error amp than what I usually practiced, saves in driver BJT's heat and helps its stability in higher voltages without any performance penalty. Sometimes I use optional protective Zeners for added mishandling safety. Not strictly necessary though. Just use D1, does most safety. 15V DC IN-DC OUT is the lower limit for adequate performance. No less than 20mA must be left running in the shunt on top of what the load demands. Here is it again showing the proper application of safety Zeners. Also a point 2 point example of mine in the second picture.

Salas:
Thank you for all your work.
Can 3μF be used for C3? I have a pair in my part box,
Thank you
Bob
 
Thought I put up something positive on this thread again... I am running the older, first version of the Salas shunt reg in two of my headphone amplifiers,
one being an Aikido and the other one a breadboard to try different pentodes on triode mode.
Well, i settled on the C3G that I already use in yet another headphone amp (OTL) and, after some parts chasing and having to find suitable output transformers, I eventually got it playing music, and very fine it does!

short facts: shunt reg set up to 80mA, 35mA and 170V into the load... C3G triode wired with 150R and Oscon in the cathode, 880R gridstoppers, vintage Grundig SE output transformers that reflect about 10K to the tube with my 300 Ohm Sennheisers, heaters DC regulated.

Initilally had some hiss and then probably low level oscillation, but after changing the layout a bit (transformers in // to have short leads to the HV regulator) and tying the heater reg to ground it started to perform.

In fact it sounds very very good... as expected it is absolutely quiet, resolution and low level detail is near maximum, timbre is very natural and rich, and this thing is FAST! I have yet to find another tube that does cymbals and hihat better than the C3G...
Shostakovich gave me the goose bumps today, Marcin Wasilewski was playing nice and mellow, and Eiving Aarset proved that it doesn't collapse when the going gets tough... :spin:

So credits again to Salas for being such a nice and inventive guy...:cheers:
 

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Initilally had some hiss and then probably low level oscillation, but after changing the layout a bit (transformers in // to have short leads to the HV regulator) and tying the heater reg to ground it started to perform.

cheers:


Great to hear its working with tube sized OPT's, I guess its time for me to start building.

How short of a lead are we talking from HV reg to OPT? This will influence my case decisions.
 
How short of a lead are we talking from HV reg to OPT?

You can see on the pic... the transformers facing towards you and two thin leads going to the left.. about 80mm I guess. But it was a big difference to before when I had the xformers placed on either side of my tube 'platform' and leads were very different in length... couldn't get rid of some strange symptoms.

Great to hear its working with tube sized OPT's,

Right, I was afraid myself that it wouldn't work but was surprised that there is absolutely no lack of bass. Maybe not as tight as solid state (M3) but still very defined and punchy... ;)
 
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