Author Topic: Neon Sequencer  (Read 2368 times)

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Offline @rt

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Neon Sequencer
« on: October 28, 2015, 05:33:34 pm »
Hi Guys,
I was wondering how a commercial neon sign sequencer works, or even a flasher where only a single tube of a larger sign flashes.
It occurs to me you could use a solid state relay to switch the mains supply to multiple neon transformers,
but that seems expensive on neon transformers.
or if there’s some way to use a single neon transformer and some way to switch kV supplies between neon tubes.
Can anyone shed some light?
Cheers :)
« Last Edit: October 28, 2015, 05:35:18 pm by @rt »

Offline SeanB

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Re: Neon Sequencer
« Reply #1 on: October 28, 2015, 05:59:26 pm »
You have 3 options for neon flashers. 1 is to have a transformer per sign, and a sequencer to switch the primary side supply, using either an electronic solution with a slow oscillator using a 555, a 4017 and a few MOC 3064 opto triacs and BT157 triacs for current boost with zero cross switching.  2, you can also use a Faraday motor, which works off eddy current in a metal disk, which turns an eccentric cam which operates 3-6 very large switches which then switch the transformer primaries. 3 is to use high voltage switches, but there are only 2 options, a very expensive high power reed switch, rated for 20kv and 500mA ( and at $400 each last time I looked, with a limited life) or a geared motor running what is essentially a motor vehicle distributor to switch the spark.

The primary side switch is the most common, it is always going to be cheaper to use an unswitched high voltage side, and simply switch the transformer. This is very reliable, the neon transformers I have are a mix of old and brand new, the old ones having done multi decade service up in a sign, switching at 30 flashes a minute 24/7/365, and there the most common failures were neon breaking from thermal shock or vandalism, or the electronic controls dying from wear. Simple modules, but as they were potted they were not repairable, as the potting used was non reenterable. I have a homopolar switch from an older sign, still works, but as it was a 4 flash instead of a 3 I did not use it.

High side switching is also discouraged as it generates a lot of very high power broadband noise, as it is essentially a spark gap transmitter, and with up to 150W of power, it is very powerful and is going to cause interference from the LW broadcast band ( 60kHz) to well in the gigaherts band.
« Last Edit: October 28, 2015, 06:03:20 pm by SeanB »

Offline matt6ft9

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Re: Neon Sequencer
« Reply #2 on: October 28, 2015, 08:42:38 pm »
Most of the time, a sign is mostly on, with only a small part of it being sequenced.  I work for a company that manufactures neon power supplies.  The main switching power supply has a 22VAC auxiliary output, running at roughly 20Khz.  This is fed into a microcontroller based board that turns on smaller boost transformers.  (The 22VAC signal is fed to the smaller boost transformers)  There is one boost transformer per segment.  This is how it’s done here, ‘doesn’t mean it’s the best way.

Offline @rt

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Re: Neon Sequencer
« Reply #3 on: October 30, 2015, 12:13:10 am »
Thanks for the replies Guys :)
Matt, I’m dealing with transformer supplies. Just a private individual here.
I always wanted a commercial neon since watching the old “Pump up the Volume” with Christian Slater.
Now I have one tube, but looking to set up a red green and blue tube on plexiglass backing.

My concern was switching the primary of a mains former. I’ve never had need to do that before,
but with he reassurance I guess it’s the way to go. I already have some SSRs.
It’s just a matter of how fast they switch to do any colour blending or PWM dimming, etc.
Cheers :)

ps.. any neon glass blowers here.. I would really like a Xenon and/or argon single electrode tube 15cm if could be done on the cheap!!
« Last Edit: October 30, 2015, 12:41:51 am by @rt »

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