Simplistic Mosfet HV Shunt Regs

[Salas]

Originally Posted by regal

Where do you guys buy these big 15W+ heat sinks? ...new technology to improve ancient but wonderful designs.

US and Canada guys may be more useful to give you heatsink sources given your location. The ''super reg'' concept, namely parallel regulation fed from CCS made with semis, dates back to the Stax company in Japan in the early 70's. Lux and Kenwood had some obscure basic ones in very few top models of their's a bit later too. The VR ionization valve diodes with radioactive trigger were the ''vacuum Zeners'' first to stabilize in parallel. If there were constant current fed, then it was the same concept. I haven't researched if they were ever utilized with referenced error amp loop back then, so to be classified as regs or just stabilizers though. Since I am a tube guy too, I wanted to get rid of the typical problems and cost and bulk of passive filters, also it had to better the Maida subjectively for there to be reason making it. Some extra heat penalty wouldn't frighten tube DIYers, used to it. I knew from myself that tube DIY hates many parts and BJTs. Mosfets and basic it had to be, if to be tested at all by my mates too. It proved that it will not block tubes tone, to the contrary. The rest you know it, its chronicled in this thread.

[Salas]

Originally Posted by massimo

we too

Allen Wright and Gary Pimm were long time proponents, unfortunately I haven't made any research on their work before doing the simplistic hv. It could have been even better if I had draw from their experience too. I based it on my low voltage simplistic reg experience and some parts. Gary has contributed early in this thread about pcb practice and I thank him for that. Also Zen Mod and his DIY pink panthers gang chanting the ''shunties'' for DIY in general.

[regal]

One last question. I'm specing my transformer and need to know how much filtering is needed (hence Voltage drop) prior to the regulator, this will be a 5AR4 CLC feed a 6c45pi SEOPT spud headamp. Is under 1V ripple OK, or do we need less prior to the reg?

[Salas]

In this post I sum it up, and I mention 15V in-out will suffice. Kill as much ripple as you can without much spending. Choke's good.

[regal]

Ballpark for input ripple of 1mV sound reasonable?

[Salas]

Super low. Anything about 50-200mV RMS I consider it good prefiltering. Especially with IRF9610 it filters good up high by itself. But you may prefer an IRFP9240 or IRF9640 for boosted gate reliability. Shifts a bit tonally to the left with heavier Ciss Mosfets, to the right with lighter. Depends on the total thing you fit it to.

[regal]

Thanks for all the help, since this is a headamp where low ripple is critical I can easily prefilter to 1 mV with a simple CLCRC filter.


One thing I wanted to ask the group, since we need to keep the shunt reg circuit by the tubes, I am finding it difficult to integrate a 30W heatsink into a classic tube chassis. Anyone have a chassis that looks good with the big heatsinks?

[Salas]

Don't know about aesthetically pleasing big sink on a tubes chassis, there must be nice configurations to invent. But a sink must be set free of obstructions with its fins perpendicular so air can flow right. Also I see many people participating in that GB for pcbs, I just hope that the layout and applications will get lucky for most, because a reg like this isn't guaranteeing it will work just with everything. Don't expect me to start debugging people's configurations if it will not play with some loads or settings. I have even seen talk about putting chokes in series and splitting after the reg. Yeah, that will be the day for its Zo or stability.

[massimo]

Originally Posted by regal

One last question. I'm specing my transformer and need to know how much filtering is needed (hence Voltage drop) prior to the regulator, this will be a 5AR4 CLC feed a 6c45pi SEOPT spud headamp. Is under 1V ripple OK, or do we need less prior to the reg?

Can you pls post a link of that schem? I searched, but no compatible results. Thank you.

[regal]

Originally Posted by massimo

Can you pls post a link of that schem? I searched, but no compatible results. Thank you.

Basically its a 550VCT 200 mA transformer CLCRC- Salas Reg - 160V - 6c45pi-Electraprint 5k:32 OPT- with an LED on the cathode, gives about 20 mA bias. I'll do a schematic if it comes together OK.