High voltage Fusor grade x-former score (Temporary)

[Dennis P Brown]

Well, I decided that instead of using a divider on the high voltage secondary (I started to do this but really had issues - and how a voltmeter has issues in the DC high end ...lol) I just tapped into the x-former's primary instead. Just needed a diode (the meter only reads DC, positive voltage) and a 3.1 Meg resistor to go with the 10 turn pot and my digital display tracks the HV perfectly. That is, I do have a HV probe but being only able to read positive values, it is a pain to setup safely and totally unsafe to leave as a permanent meter. However, did demonstrate the required voltage ranges to tune the display. Very linear over the entire scale - from 5 kV to 32 kV.

While I realize that there may be issues tapping the primary rather than the secondary when the fusor plasma arcs or fails or any number of things, this voltmeter's only purpose for me is to read a voltage for steady state situations. Once the variac is set, I'm not too concerned with display variation compared to any 'real' secondary voltage until the fursor reaches the steady state - especially since, using the higher end range voltages, current is the only real issue. And another thanks to Mr. Reite for the connecting the x-former's positive HV output to the milli-amp meter. Works great (especially since that is a required ground point for the diode bridge.)

Decided to wait to install the master "on/off" switch until I can borrow a panel punch. Drilling a square hole isn't too easy! Getting impatient for the new glass chamber window. Can't do anything until that arrives and is drilled for an electrode. (Currently, there is an on/off switch to enable the HV x-former to come on.)

Did get a small piece of uranium to better test the Geiger/scintillation counters as well as to cross reference them against each other and test various voltage settings for the units.

[Dennis P Brown]

Finish all the safety work relative to the fusor power supply (that I can readily think of... for instance, have really gone over and over grounding issues - for the x-former, bridge, cables, fusor, enclosure, fusor HV, and even the AC line current.): so added a master power switch w/light, better cable protection features, warning stickers and a plastic shield cover over the top of the HV section when the cover is open (the rear door has both a warning sticker and key lock. Still have to finish the business (fusor) end of the high voltage cable. Have a ceramic section for that and will install that so the "hot end" isn't easy to contact.

Obviously, I am far more concerned with the high voltage hazard than any other; I have multiple x-ray detectors (some calibrated) but with my steel chamber, it is the electric that is hardest safety issue to address with any confidence.

[Dennis P Brown]

Installed and tested the ceramic end adapter for the high voltage cable (see below.) The resistive tester rig (unlike my first iteration) can be adjusted to handling longer resistors. The new end cable adapter system held the full voltage nicely. This system works well for the fusor but being 2 .3 M-ohm, does keep the current draw rather low - see last photo.

Getting impatient (like building a special rig for testing the cable - yes, useful for general fusor tests to have a resistive load device - speaking of which, there was an entire thread on this subject but really, I'm getting too far afield, here) to test the fusor - hopefully, the person ships the new window early this week and I get it in time to drill it, add the electrode and test the power supply in the few micron range by this weekend (with deuterium gas for fun. No way yet to measure neutrons.)