A HV lab supply

[triode_al]

The past few days I have been working on a variable high voltage power supply, to make life easier.
I decided to create a CCS that outputs a constant current into a reference resistor, with a buffer (gate follower).

HV laboratory supply.pdf
(I am lost how to get a decent postable picture from my simple drawing tool McCad)

This works like a dream. Very stable. At 2 mV setting of the scope, the output remains completely flat (and our mains is very very fluctuating).

Noise (excluding hum) is almost absent. Less than 0,5 mV.
Hum is visible. Measured on scope less than 3 mV peak-peak 50 Hz, from the pick-up on the long (30 cm) leads to the potmeter I use, and the unshielded 20 turns potentiometer itself.
With a more careful layout and proximity it can be beter even, but hey, 100 dB is not bad. For instance hum already dropped from 10 mV PP to 3 mV PP by earthing the case on the front panel.

The unit ranges from 68 Volt to 315 Volt. This is of course determined by the reference resistor, I choose 100K.
I also added a 6,3 output as that is handy too.

As an extra I think of adding an electronic choke, that also limits the output to about 200 mA.

Albert

[triode_al]

An update:
The schema, updated:
schema PS 2011-70.jpg
Here is a picture of the outside
HV PS exterior 2011-68.jpg
and the somewhat messy insides:
PS innards 2011-69.jpg
you can see the big rectifier tube 5RU4 and the 6J5 single triode.
I have a big PIO and a starter capacitor (top left) below the provisional voltahe divider for the tube heater. The outside and specs only matter

The CCS is composed of a 2SK30, that manages the triode's current into 100k.
The active choke was taken from A.M.Quinn's website. I have not yet attached this active choke.

albert

[escopunk]

Love that analog amp meter, inspired me to make my own HV power supply, gonna go tube (6L6 or 6550) with solid state rectifiers.