Convert tungsten fairy lights to LED. (plus ramble)

This is one of those projects that is not only fun and therapeutic to do, but gives you a really versatile set of lights for life. You can support this channel at   / bigclive   I've covered this style of project before, but it's a great one, so worth covering again. This project is really intended for the short 20 lamp tungsten strings common in the UK and some other countries. It can be upscaled slightly depending on your mains voltage with a change of resistor value and increasing 100/120Hz flicker with higher numbers of LEDs. 20 is the simplest though. The LEDs are deliberately run at very low current (around 3mA) for use as subtle background decoration. You can mix and match LEDs to your hearts content. Keep in mind that the LEDs are still operating at mains voltage just like the tungsten lamps they replaced, and also note that while the power supply is super simple it is also at mains voltage and should be enclosed for safety. The whole string of lights will draw half a watt in use and can be left running 24/7 with a negligible running cost of something like 50 pence/cents a year. It's actually worth getting two sets just for the spare lamp holders in the other set. They can then be loaded up with LEDs of your choice for swapping in and out for fun.