Need advice on a neon transformer

30ma is more available power, so it is better - the transformer will handle a larger load. Your transformer may not be putting out 5KV though...

This is where an AC/DC HV probe is handy. You can get 10:1 on eBay and other sources. Look for ones that appear to be well insulated! If it comes from China don't stand on a cement floor when using it!

John :-#)#

The extra current may be damaging the electrodes and causing out-gassing or overheating the tube so the neon pressure rises. Is there a possibility that there is an adjustable magnetic shunt inside the transformer that could be adjusted to reduce the current?

Please be careful - with those sorts of currents and voltages, your first mistake could well be your last.

--
~ Adrian Tuddenham ~ 
(Remove the ".invalid"s and add ".co.uk" to reply) 
www.poppyrecords.co.uk

is

d e g

Interesting, I did not realize that Neon transformers were current limiting, behaving somewhat like a ballast on fluorescent lamps:

--------------(quote)---------------------------------------

Neon sign transformers have built-in magnetic shunts which give current limiting. In its intended use as a supply for neon tube, the high open circuit voltage of the transformer is used to strike an arc in the neon tube. Once an arc has formed inside the neon tube, the current must be limited to prevent overheating of the neon tube and the transformer due to excessive current flow. (The hotter the arc gets, the more current flows, so it gets hotter etc?)

----------------(end quote)----------------------------------

Thanks for the info! Live and learn, eh?

John :-#)#

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Exactly like a grown-up version of your tiny neon pilot lamp in an AC power socket with its ballast resistor...

Mike.

HeNe laser supplies are the same way. You have to match them to the tube.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC / Hobbs ElectroOptics 
Optics, Electro-optics, Photonics, Analog Electronics 
Briarcliff Manor NY 10510 

http://electrooptical.net 
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I have a Neon Christmas tree (glass tube outline) that was made for my grandfather by his employees (E.L. Ruddy in Toronto) during the depression (as Granny told me years ago). Stands about 14 inches tall and is still working just fine. Haul it out every winter and plug it into its base.

I can post a picture if anyone is interested...

John :-#)#

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I certainly wouldn't mind seeing it John.

Old photos, that don't show the metal base. All I have at the moment. It is sitting on a 1929ish RCA radio, sitting on a 1920s radio speaker cabinet. Photos taken almost twenty years ago.

John :-#)#

my

How refreshing that the shape has an smidgen of randomness!

Mike.

My thoughts exactly.

'Twere mine, I would put it up every year too. To remember grandpa and because it's cool.

a and

Exactly. It goes up every year for a month or so...

Thanks,

John :-#)#

Nice. Did you ever consider building a lexan box to mount it in?

No, my family are careful around it and we no longer have a cat...

I agree it would be very unfortunate if it ever broke.

John :-#)#

Well you're overloading the neon tube and may cause damage to it.

I found some 4kV 15ma electronic power supplies online. Might work fine.

As a test, you could put a 330K resistor in series with the neon tube. That will limit the current to 15 mA.

However, the power rating needs to be in excess of 75 watts.

--
"I am a river to my people." 
Jeff-1.0 
WA6FWi 
http:foxsmercantile.com

As well as the constant high voltage.

Did it rub against the transformer?

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~ Adrian Tuddenham ~ 
(Remove the ".invalid"s and add ".co.uk" to reply) 
www.poppyrecords.co.uk

The photo doesn't show the chrome metal box that the transformer is mounted in. The HV outputs are in two chrome metal tubes that the tree plugs into...

John :-#)#

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                      John's Jukes Ltd. 
MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 
          (604)872-5757 (Pinballs, Jukes, Video Games) 
                      www.flippers.com 
        "Old pinballers never die, they just flip out."