Making a set of retro neon fairy lights. (100 year anniversary.)

This turned out really well. It's a set of fairy lights / Christmas lights that are based on neons that run in a parallel circuit with two resistors per neon. It could have been a single resistor per neon, but by using two it spreads the heat dissipation, packs out the base nicely and adds a layer of safety and reliability.
I didn't realise until I started writing this video description that the humble neon indicator lamp is 100 years old this year (2019) having been patented in 1919. Happy 100th birthday lil' neon lamp.
https://en.wikipedia.org/wiki/Neon_lamp

If you build a string of these then please remember that they operate at mains voltage and extra care must be taken to sleeve and secure connections. I actually missed a heatshrink sleeve from one of the lights leaving live contacts exposed, so take care to double check before powering the string up. The wire should be rated for mains use and ideally would have been double insulated, but it's quite tricky to find double insulated single cores.
A suitable fuse should be used in case of an incident, and a humble 1A fuse will theoretically handle 1000 lights or more if run at less than 1mA per lamp.

I used standard NE2 indicator lamps which I bought from a local mail order electronic supplier, and used two 100K resistors for our 240V supply. If making a set for 120V you can use a lower value resistor like two 47K, but the neons will light fine with higher value resistors. The intensity will reduce with higher value resistors and the glow may become unstable and shimmer about inside (which is a really nice effect). The life of these little neon lamps is rated in tens of thousands of hours of continuous use, with lower currents giving longer life.

This is definitely a project for seasoned electronics tinkerers, since it does involve a lot of mains connections. But it's also a very therapeutic project to build a set as long as you want. You could use green, blue and white (if you can get them) neon indicators too, but they will be a bit dimmer and you definitely want to run them at reduced current to avoid blackening.

The supplier I got the neon lamps from was Rapid Electronics in the UK:-
https://www.rapidonline.com/electroni...

You can also get them on eBay if you search for things like 100pcs neon indicator with the option of blue and green too. I recommend the 6mm diameter lamps as they are stronger, brighter and longer lasting. If the ones you get have a spot welded resistor on them I recommend replacing it with a higher value one for cooler running and longer lamp life.

The slight alternating of the glow from side to side in the video is due to the way each electrode illuminates alternately at mains frequency. The camera shutter speed makes that visible.

You can deliberately make the glow discharge unstable in the lamps by adding a capacitor in series with the whole string. It causes a slight interaction between the lamps and can make some of them shimmer like little neon flicker-flame lamps. With this short string of 13 lamps I got a good effect with a 47nF or 100nF suppression capacitor. Remember to add a 470K discharge resistor across the capacitor to avoid getting a plug-tingle from residual charge.

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