100v dc from 150?

[allmighty1]

Hi guys, my first post here. I have a design I was given for a simple valve buffer requiring 100v dc. I have a 110v secondary transformer (80va, should be plenty)
which will give me about 150vdc. Can anyone give me a suggestion for a regulator which will bring this down to the 100v I need?

 

[Osvaldo de Banfield]

Which materials do you have in a junk, or what technology do you want to use?

A resistor and a simple VR105 (Like a zener in valve state) will perform. A linear regulator using semiconductor is pretty fine, buy a bit more complex. Finally, a SMPS like Buck topology is more efficient but more complex too.

Also a simple drop resistor will do the job too.

 

[allmighty1]

I'm afraid my design capabilties have a few large holes in them. But I can follow a circut diagram. I've searched for a simple regulator (ala lm317) but none seem to be available in this range. Can you suggest a discrete regulator regulator design I could build on strip board?
I know I could make a voltage divider in a 1-2 ratio but how do I size the resistors so as not to limit the current too much and not to have it all run away to earth. I know this is super basic stuff but I learn quickly with a little encouragement. Thanks.

 

[v4lve lover]

Try a mosfet source follower. Bias the mosfet whit a zener diode.

 

[Elvee]

I've searched for a simple regulator (ala lm317) but none seem to be available in this range. Can you suggest a discrete regulator regulator design I could build on strip board?

It very much depends on your requirements: current first, then ripple rejection, and finally output impedance, necessity of soft start, current limiting, etc
I have described a number of regulators, here and there. The most structured thread is here:
http://www.diyaudio.com/forums/power-supplies/198986-simple-hv-series-regulators.html
(others are answers and are less complete)
It is probably overkill -or not- ; depends on your actual needs