[time-nuts] "The Penultimate HP5065 A15" <C field switching>

[cdelect at juno.com]

>> 	C-field polarity switch.  An experiment.  If nothing else
>> 	I will be able to measure the residual magnetic field.

There is no requirement to do any thing other than switch the C-field
polarity.
No optical stuff needed.

The PRS10 switches the C-field polarity at a 5HZ rate to reduce magnetic
effects and does not do any optical tricks!

Back in Nov 2017 I detailed my A15 mods:

Set Zener current to minimum TC (I achieved < 1PPM/C at the +20V output)
This involved disconnecting the C-field circuit and replacing it with a
dual (in series ) LM299AH and 1PPM resistors.  Jumperable settings and a
low TC pot for adjustment. I would have liked to use 3 LM299AH to give me
21 Volts but would need to switch the input to the unregulated supply to
give enough overhead. The higher the voltage into the C-field string the
lower the TC contribution from the C-field coil itself.

The posts have the details and schematic.

Cheers,

Corby