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Antique HV Device Question/Help

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Josh

Fri Apr 01 2011, 06:20AM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

I'm wanting to buy a violet ray for being a HV antique...
Plus restoring it seems like a fun project.

However I was reading online regarding them and came to Stefan's website.

From what I can understand they are far from safe in their normal state.
Running one from an inverter with a MOV, and RLC makes it safer to use.

My question is if I follow what he says will it make it sufficiently "safe"?
Does anybody have experience restoring a working one electrically?

Josh

Sat Apr 02 2011, 01:16AM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

Nope this isn't an April fools joke, I'm serious....

Sulaiman

Sat Apr 02 2011, 07:45AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

For simplicity and safety you could just use a small induction coil ('spark coil', 'Ruhmkorff coil')
e.g.

etc.
You can make one yourself using an automotive ignition coil, a relay and capacitors.
Powered directly from a battery (12V lead-acid, NiMH or Lithium pack etc.)

If you use a 555 & mosfet/igbt to drive the ignition coil you can experiment with different power/frequency combinations for slightly different effects.
(DO NOT use any circuit that has a 2N3055, a higher voltage transistor is required)

Arcstarter

Sun Apr 03 2011, 02:00AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

You will want to make sure you got one which you know the primary and secondary are good, that would not be fun to try to fix, as i am pretty sure most of them are potted. Other than that, there is not much that could go wrong electrically speaking. Worn down or dirty contacts, bad capacitor, and a bad 'kicker coil' are the main things that would go wrong.

As for safety, they should be plenty safe. Like he said on that page, they are unsafe *if* plugged up with the wrong polarity. Using the neutral line is just as safe as using the earth ground, as they are sometimes the same electrically! I helped wire up my brother's trailer to mains, and in the brand new meter box, the neutral buss is grounded with a spike in the ground... And that is the only grounding the whole trailer has. So, all earth grounds are actually just another connection off the neutral line. There are 3 wires running to the trailer, one hot, one neutral, and one ground, but the nuetral and ground are hooked up to the same buss bar.

Steve Conner

Sun Apr 03 2011, 10:19AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Neutral is often the same as earth in practice, but it can't be relied on. The details of this vary by country, but using the neutral as if it were an earth (or vice versa) is against the electrical code everywhere. The protection and return functions are kept separate, so an electrician has to screw up twice before anyone dies.

If you want to do it (and when did we ever bother about electrical codes here?) then it is advisable to check every new outlet you use your device with, to make sure that the hot and neutral aren't swapped, for example. You may also be able to add a Class Y capacitor somewhere, to get a RF ground as well as isolation at 60Hz.

If it were me I would modify the thing to take a 3 prong plug, the bottom of the secondary being connected to the green wire. Or get a 1:1 isolation transformer, and ground the output that should be "neutral".

Xray

Sun Apr 03 2011, 06:03PM

Registered Member #3429 Joined: Sun Nov 21 2010, 02:04AM
Location: Minnesota, USA
Posts: 288

I have one that I bought on Ebay a few months ago. This particular one shows no DC resistance between the hv tip, and either of the AC mains connections, so I can assume that there is a high-pass capacitor in the circuit that blocks the low frequency 60Hz voltage.

There are many different Violet Ray designs -- Some have the kicker coil and interrupter contacts mounted in the carrying case, and some have them mounted in the hand-held unit. Mine happens to be the type where all electrical components are mounted in the hand-held unit. That type is more convenient because you don't need to lug around the carrying case just to use the device in another location.

Mine works great, but be aware that many Violet Ray units that you buy on Ebay either produce a very weak output voltage, or they don't work at all. One red flag to look for: If a seller makes a statement such as "It's old and I'm afraid to plug it in", then you should assume that it doesn't work!

I use mine for testing X-ray tubes for gas. I converted the original clip that held the glass applicator bulbs to a standard alligator clip, and I brought a ground wire out the rear to be used as an electrical "return". I also replaced the original 2-wire AC cord with a 3-wire cord that has an earth ground connection.

Josh

Mon Apr 04 2011, 07:08PM

Registered Member #938 Joined: Sat Aug 04 2007, 05:39AM
Location: Honokaa,HI,USA
Posts: 65

Thank you guys for the input and suggestions!
I'll get a working one off of ebay, fix up contacts,
replace the capacitor and such then follow Stephen's instruction.

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