Talk:Neon-sign transformer

Dear sir,

Is it possible to generate Infra Red light waves instead of other colours in Neon signs.?

maheshkrishnan@avalontec.com

My humble Answer: This sound like a Laser--a close cousin. Try googling/wiking IR lasers.70.176.118.196 (talk) 14:25, 9 April 2011 (UTC)

Other Uses?

It is possible to charge capacitors directs from an NST's AC output. A Marx-type generator, or voltage multiplier, uses an AC input. The multiplier, however, Does use rectifiers in its stages.The Marx generator fires a spark gap when caps are charged, then discharging them in series.

Types?

Please mention no Neon transformers were ever made over 60 mA output. Any 120 mA devices, or greater, are for bombarding (bench burning-in of Neon tubes.)

Also, an AC transformer is 98% efficient--the switch mode "electronic Ballast-type do Not exceed this efficiency. They are only lighter, quieter, and won't drip tar on the rug if they get hot.

Switch-mode Electronic Ballasts are simply 85% efficient compared to the 35% or so of an analog power supply.

Switch-mode transformers are No Good for Tesla coils--the back RF will fry them, instantly. Plus they are not designed to work into a capacitive load. Perhaps an RF filter can be added, but their switching frequency of 15-25 kHz sometimes approaches the operating frequency of the Tesla coil, and precludes this.

An RF filter must always be added between the output of a transformer-type NST and a Tesla coil, or the back EMF can cause internal carbon shorts in the asphalt potting. These can be fixed by removing the tar, but it is very delicate, messy work.

Transformer-type NST's have a center tap (grounded) when they produce about 10 kV or more. This makes for two hi voltage output windings, insulated for 1/2 the output. Saves insulation and costs. It is safer to run this way, too.

The current-limit in a transformer-type is a magnet "shunt"--a split in the normal "tongue" of the center lamination that is designed to reduce flux on load. This is the opposite of a normal transformer, which will provide much more current than designed for if shorted, until it burns out a winding.

The current limit is to provide a high voltage starting "pulse" to the tube, then to limit current, and, hence, power to the tube. The short-circuit current is equal to the rated current, an AC ammeter can simply be placed across the hi voltage outputs to test it. The average short-circuit/full-load output voltage is 800 volts.

Also, the asphalt in old-fashioned transformers is for Noise--not weatherproofing or insulation., They are well-sealed in a steel box for outside use. The newer ones for indoor are potted in epoxy. They will run fine without tar--in fact, if asphalt removed (Very Carefully!), and they are immersed in oil, the shunt can then be bypassed for safe, short bursts of even greater current. There is much less chance of an internal short, too.

Also, many newer transformer-types have ground-fault interrupters ("GFI's") built-in, which will trip/fry if it is used in a Tesla coil. These should be obviously not be used in Tesla coils, or the GFI removed/bypassed.70.176.118.196 (talk) 14:17, 9 April 2011 (UTC)