I have always been a big fan of taking stuff apart, so when we had some lightbulbs mysteriously die I had to take them apart to see what killed them. Unsuprisingly, upon inspection I saw 2 LEDs that had completely blown up. Instead of throwing everything out however, I decided to reuse the shell in one of my own projects.

I had some small rechargeable batteries laying around that happened to fit perfectly inside of this lightbulb shell, so I set out to make a self-powered lightbulb that would turn on if you touched the metal contacts, more simply described as a “Magic Light”.

I used this project to finally force myself to learn and get comfortable with Altium Designer. I also wanted to avoid the boring rectangular board first step tutorials that you see online. So this board was going to be made in 2 separate parts, keying into eachother in the end. I used Fusion 360 for determining board shape and exporting it into Altium.

The design is based around a simple PNP darlington transistor pair, if your body touches both metal contacts, a minute current will flow through, throwing the transistor pair on. This will then enable the LED driver and turn on the LEDs. Charging it is also simple, simply apply 5 Volts onto the screw terminal and the charge IC will begin to charge the 80 mAh battery inside.

For safety, A TVS Diode and fuse was added to the input, so if somebody were to inadvertently screw in the bulb into main voltage the current would go through the TVS diode and immediately blow the fuse (probably…) Realistically, I am the only person interacting with this, but it would be rather unfortunate for it to turn into a claymore if it accidentally got into the wrong hands.

Overall, this little light works great, it can light up an entire room by itself and it can run for around 10-15 Minutes at full brightness before the LED driver switches modes due to low voltage.

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MD