Is it bad to turn neon light on and off by wall outlet?

[Dman777]

I just got a new Xbox neon light sign. I also bought a wifi smart outlet so I can turn it off with my Google Home and Echo. 

I noticed that when I turn it off by the smart outlet, the neon sign turns off differently. The letters have a unique pattern when they turn off. This is not the same behavior as when I turn it off by the sign's native switch...then all the letters go off at once. 

Is it bad for the neon sign or hard on the circuitry to be turning it on and off by the wall smart outlet switch instead of the signs normal on and off switch?

Here is a video of sign being turned off by outlet

[gregebert]

I suggest you try another experiment: Try pulling the plug to turn it on/off. Does that mimic the way the sign turns off with the smart outlet ?

Once you have that info, we can speculate about what the power switch in the sign does, and also the smart outlet. It might not be a simple series-switch like most appliances have; it could somehow be tied into the power supply, which would explain why the shutoff is different

 

Does the smart outlet click when turning on/off ? If so, it's a relay. If not, it's probably a triac. They have different turn-off characteristics.

Is the sign 2-conductor (neutral & hot), or 3-conductor (neutral + hot + GND). I've seen really weird things happen with noise coupling between neutral and GND.

[Dman777]

I haven't got a opportunity to try the experiement you suggested yet, but yes... there is a loud physical click when the wifi smart outlet turns it off...like something physical moves. 

Because of this, do you think I might shorten the life of my sign if I don't use the on and off switch built into it?

Thanks,

-Darin

[Nick]

When you turned the Xbox display off by the remote, it is obvious that there is a programmed shutdown in the way that the letters turn off from the middle out, i.e. it's a software shutdown (there's a CPU in there probably controlling the SMPS and doing the cool display digit effects).

When you switch the mains off, that's it. It turns off.

Turning off the mains via the smart socket will not hurt the neon and SHOULD NOT hurt the control electronics of the display.

Nick

[Dman777]

Thanks! That is fascinating!  Question though.....

When I got the neon sign there was a warranty notice that said do not use a dimmer or else. Would this gradual power decrease by the remote outlet switch be the same thing? 

Thank you,

-Darin

[gregebert]

The click indicates you have a relay, which is good. It's as close as you can get to plugging-in.

As far as a dimmer, they operate by triggering a triac at a controlled delay into each AC cycle (the longer the delay, the dimmer an incandescent bulb will be). This switching can wreak havoc on a switchmode power supply.

A well-designed power supply would not be negatively impacted by the smart outlet; cost and schedule pressure often results in designs that aren't bullet-proof. I wouldn't be surprised if your sign died within a few days if you turned it on and off once per second from your smart outlet. But that's not a realistic usage case. My gut feeling is that it's probably OK what you're doing. The only way to know for sure is to study the schematic and do extensive testing, which isn't possible.

[Terry S]

It's possible that the power supply has circuitry that quickly discharges the high voltage (maybe as simple as a bleeder resistor inserted by the switch) when shut down by the switch. In the case of unplugging or the wifi switch,this circuitry would not be activated, resulting in the fade out in the video.

I have beer neons that exhibit the same behavior when I unplug them -- never tried to compare that to the pull-chain off sequence. But now you have me intrigued, so I will try that this evening.

I really can't envision a scenario where this would be harmful to the supply or the sign. I've been turning my neons on & off by wall switch, power strip switch, or unplugging them for years. I have not had a failure on any of my signs (over 20 of them) -- although I've bought many with already failed supplies.  Cheap because of that.

Terry

On Monday, April 24, 2017 at 9:20:46 PM UTC-5, Dman777 wrote:

[Terry S]

Respectfully disagree, Nick, this is simply the high voltage dropping off, with the gaseous tube ends nearest the supply connections de-ionizing last. Neon signs like this would be too cost sensitive to implement with individual control over each letter. It's typically one long tube, or in this case, two tubes of different colors.

Terry

On Monday, April 24, 2017 at 11:09:32 PM UTC-5, Nick wrote:

[Nick]

Yep. Could be Terry. I did wonder if individual control would be viable - i have made neon letters and signs from scratch but not seen them turning off from the middle. Maybe it's a function of slow HV decay on the SMPS? It would be good to characterise the behaviour...

Anyway, the concencus is that your display is unlikely to be damaged by the smart socket.

Nick

[Terry S]

In case anyone is interested in more neon..... a sampling of my signs.

Terry

https://www.flickr.com/photos/32165280@N02/albums/72157632317636464

[Nicholas Stock]

I need some neon for the man cave...well apart from all the nixies/dekatrons etc......a proper neon sign....

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[Terry S]

Craigslist is your friend.... but beware, they tend to multiply.

On Tuesday, April 25, 2017 at 8:45:57 PM UTC-5, Pramanicin wrote:

I need some neon for the man cave...well apart from all the nixies/dekatrons etc......a proper neon sign....

On Tue, Apr 25, 2017 at 5:53 PM, 'Terry S' via neonixie-l <neoni...@googlegroups.com> wrote:

In case anyone is interested in more neon..... a sampling of my signs.

Terry

https://www.flickr.com/photos/32165280@N02/albums/72157632317636464

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[Nicholas Stock]

What's the average lifespan of a good neon sign then?

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[Terry S]

Decades. If the glass was done by skilled craftsmen, they simply last decades. I have signs from the 70's and 80's. But so many new units are made in China, and the quality is poor. The modern lightweight power supplies vary a great deal in quality, too.

[Nicholas Stock]

Steer clear of Chinese eBay neon signs then....I will give Craigslist a whirl....not without its own caveats, but I'm game...

Thanks,

Nick

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[Terry S]

Finally had an opportunity to test this -- and I can confirm that on at least a couple of my larger neon signs, the tubes shut off differently using the pull chain switch than they do using the line cord.

I have one large Boulevard Brewing sign, for example, that shuts off slowly, with the long border tube being the last to de-energize, in four distinct segments, when unplugged. By contrast, the entire sign shuts off immediately when I use the switch.

So I can only conclude that the power supply must be bled down quickly when the switch is toggled.

Terry

[alb.001 alb.001]

I always build high voltage devices with a double pole double throw switch so that one pole controls power while the other pole puts a 10 K resistor across the HV supply to bleed it off  when device is turned off.  Never been buzzed this way.

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[Terry S]

Most pull chain switches - as used on neon signs -- are the old style, single pole single throw, ratchet/rotary action switches. Some with multiple brightness levels or flashing action have a slightly more sophisticated switch, multiple poles, but still are only single throw. I'm not sure how the bleeder resistor is accomplished with those style switches... certainly they are not rated for the HV levels present on the outputs. And the bleeder resistor can't always be in place because the wattage rating required would make the size enormous. Yet there must be a mechanism triggered by the switch that drops in the bleeder, or clamps the HV electronically. 

Next time I encounter a failed neon supply, I'll dissect it for clues. 

Terry