Neon Signs

[Tom Harris]

Sorry if this is the wrong group. I have been offered a large quantity of vintage neon tubes from old signs, "burgers", "restaurant" "cafe", that sort of thing, together with straight & curved lines. How do I find out the value? I can test them.

Tom Harris <celep...@gmail.com>

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[Nick de Smith]

Not the wrong place at all. There are Neon tube testers, small battery powered units, that can test to see it if the tubes are OK.

Where abouts are you located - there may at be a member near you who can help or lend you a tester...

Nick

--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

[Tom Harris]

I have several neon transformers that I could use for testing, one with HV leads ending in croc clips. I call it Cousin Vinnie, as if there's a problem, Cousin Vinnie will fix them :) Still a pocket tester that will  not kill you outright sounds a good idea. I've seen sparkies using them to test fluoro tubes.

Tom Harris <celep...@gmail.com>

[Tom Harris]

Are the cheap fluorescent testers on ebay that cost $15 or so and take 4 AA batteries any good?

Tom Harris <celep...@gmail.com>

[Terry S]

Tom, the sad fact is they will have little value, unless they are specific to beer or automotive signs. Generic words probably won't sell.... now maybe you can get creative and construct some signs to peddle to local pubs or eateries... The standoffs can be purchased on-line and mounted to black plexiglass. The GTO wire is  little pricey but can also be found on-line, as can the wire caps.

Terry

[Terry S]

They work "well enough". But the output voltage is unspecified, so expect that some good tubes will not light up fully, and some bad tubes may still light up partially. Experience will help you tell the two apart.

Terry

[NeonJohn]

Don't want to sound flippant but they're worth what you can sell 'em
for. Watch ebay and see what free pieces of neon go for. recognizable
shapes and letters will bring more.

FWIW, I get $30 for 9" plain block letters that I've collected. More
for script, especially if it says something. $20 for random designs and
logos or part of logos. Note that these are my salvage prices and NOT
what I'd make them for.

John

On 05/12/2016 07:02 PM, Tom Harris wrote:
> Sorry if this is the wrong group. I have been offered a large quantity of
> vintage neon tubes from old signs, "burgers", "restaurant" "cafe", that
> sort of thing, together with straight & curved lines. How do I find out the
> value? I can test them.
>
> Tom Harris <celep...@gmail.com>
>

> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
> Virus-free.
> www.avast.com
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> <#DDB4FAA8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>

--
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[Mike Harrison]

On Fri, 13 May 2016 09:02:52 +1000, you wrote:

>Sorry if this is the wrong group. I have been offered a large quantity of
>vintage neon tubes from old signs, "burgers", "restaurant" "cafe", that
>sort of thing, together with straight & curved lines. How do I find out the
>value? I can test them.

there's a pretty thriving market for these as decorative items - try ebay completed listings for a
start

[gregebert]

Transformers specifically designed for neon signs are perfect because they are intentionally current-limited, and the exact voltage isn't critical.  I've lit all sorts of neon tubes with my 5kV sign transformer.

I've had mine for 40+ years and never got shocked (only slight tingle). I don't know if it's because I'm overly cautious, or because it's current-limited. Considering all the items I've zapped/tested/abused/etc over the years, I'm amazed this transformer still works.

NEVER use a microwave oven transformer; they are deadly because there is no current-limiting, and their voltage is probably too low anyways.

[NeonJohn]

On 05/13/2016 01:57 PM, gregebert wrote:

> NEVER use a microwave oven transformer; they are deadly because there is no
> current-limiting, and their voltage is probably too low anyways.

A MOT actually IS currently limited using the same stray flux technology
as neon transformers. If you look at a MOT, you'll see the center leg
has an air gap just like NST. The dangerous part is that they current
limit at several AMPS at about 2kV. Very deadly.

But very handy too. You can saw the secondary off, put a few turns of
welding cable in its place, add accessories and have a mighty fine spot
welder. The stray flux limits the current so you don't blow a breaker
with the short circuit during spot welding.

Take two and connect the primaries voltage additive, figure out the
correct number of turns and connect the primaries to 240 and you have a
fine welder. You can vary the current by varying the air gap. More gap
== more current. I once made a handy little portable welder by cutting
about a half inch off the center leg and then arranging a lead screw and
nut that drove a wedge of laminated iron into the gap. Retracted wedge
== more heat.

Because they're so handy, I grab every MOT I can get my hands on.

John

[Jonathan Peakall]

Ya beat me to it. Plus, series/parallel 'em under oil for a VERY nasty
HV power supply. I've run Tesla coils on them and other silly things.
But they are QUITE lethal.

I grab every big older MOT i see. The new ones, meh.

Jonathan

[gregebert]

> Plus, series/parallel 'em under oil for a VERY nasty  HV power supply.

[...]

Curious how many you've cascaded, and what kind of oil you use.

I've been tempted to build a Tesla coil for many years, but we live too close to an airport so I'm concerned about the RFI impact on comm & navigation .

[Jonathan Peakall]

I have done a 2X2 series/parallel and a 4 in series. I used mineral oil. There are better oils but I could get 5 gallon buckets of mineral oil from a local feed store.

You also usually need to add some current limiting.

A small Tesla coil won't hurt anything. :-0

Jonathan

--

[Nick]

The thing about MOTs is they are built to a price and have some quirks, e.g. one end of the secondary is connected to the core/ground. If cascading MOTs, generally you would disconnect the wire from the core and daisy-chain the secondaries but that then means that there is suddenly 2000V (or a multiple thereof) between this wire and the core when the insulation in the transformer was designed for zero volts. Further, you are also uplifting the voltage between the primary and secondary way above what it was designed for.

If using MOTs in parallel, they should be identical models (obviously).

i.e there are some serious safety issues here. Even a small MOT-driven device could cause serious injury or worse.

These sorts of voltages and currents can easily kill.

Basically, if you're not experienced in HV, I'd avoid MOTs.

If you really want to build a TC and are not especially drawn to retro, i.e. spark gap designs, I'd recommend a small SSTC or DRSSTC (doubly resonant solid-state Tesla coil).

These are pretty straight-forward, extremely satisfyingly and DRSSTCs can be audio-modulated. Lots of standard designs out there and lots of help on forums such as 4HV. Pre-wound secondaries and all the bits (primary tubing, toploads, insulators etc.) can be found on eBay.

HTH

Nick