开云体育

OK.

My only other suggestion is increasing the
zener voltage, such that the reference voltage becomes larger
compared to circuit errors. Then, when the [744K trimmer]
resistor between Q2 and ground gets larger to bring the current
back down, the 66M resistors also get smaller still, as less
multiplication of reference voltage is required. Less
multiplication means smaller circuit error in the output.

The dominant circuit errors are (mindsim
conclusions. :-)

1) delta-Vbe between Q1 and Q2 due to
generally different bias currents, and,

2) loop gain error in the feedback regulation.
If the multiplication ratio is lowered, the loop gain improves
by that ratio. This is then lowering loop gain error by the same
ratio.

I might assume you have a convenient reason
for sticking with a 5.1V Zener, but if you put two in series, or
use a 20V zener, you will get better regulation with less
circuit error.

rogerw

Roger:

?Yup increasing the dropper resistor from 1M to 2.2 or 3.3M would
improve the shunt regulator's performance, but some of my
scintillator probes have low impedance resistor divider networks ~
10M( and hermetically sealed shut)

So I can't tolerate a 2 ~ 3M dropper unless the power supply has
sufficient head room. On the other hand, its not likely that I
would use? a power hungry probe that often.?

May be? I will migrate to a 2.2 or 3.3M dropper in the future. I
got to experiment more. Not really a logical reason but I
typically like to leave most of my stuff set to about 900V even if
they are adjustable.

Some probes are significantly more sensitive than others? so I can
drop the HV to use those probes. Next time I have my CDV-700 6a
open I will check the HV. I actually have two 6a's, one has the
original Victoreen?

regulator tube and the other has a zener string. If either is way
off from 900V, I will like to put this circuit inside.I could also
embedded this circuit into a cable.


P

-- 
rogerw
On the Catclaw
ΜΟΛΩΝ ΛΑΒΕ

The PanDemic is over, but the DemPanic goes on.
MisDisMal is a dictator's tool of repression.