Hi,
can the VB408 voltage regulator ( 
http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXttvuy.pdf 
) be used as a constant current source as shown in the picture (provided 
Iout<40mA)?

I've never used this regulator, but with a coarse view of the data sheet 
I think this will be possible - within a range between 1.2mA and 40mA.

Thanks, that's exactly what I had been hoping for. Guess I'll give it a 
shot.

It passed the smoke test and appears to work.
BTW: The VB408 is no longer in production, but I had a couple stashed 
away. The only other high voltage regulator I know of that is still in 
production is the LR8, but that one is limited to 20mA.

This is an action like pigs feed with pearls!

> This is an action like pigs feed with pearls!
You are very welcome. I hope you enjoyed your meal.

Thus reacts somebody who stands no truth - with insults!