Inside a Homedics steriliser unit - with schematic

This is one of many similar products that cashed in on the pandemic by offering products that would sterilise phones and other objects with UVC energy.

To be fair, this one has a better design, since it allows for greater distance between the UVC LEDs and the object, and it actually drives the LEDs at a fairly significant current. It could actually find use as a lab sterilising device, although the LEDs can't yet compete with traditional mercury vapour UVC sources.

The circuitry in this unit is surprisingly complex. It has the signs of being a "proper" design without the usual penny pinching shortcuts found in similar products. The thermal sensing in the lithium cell is a nice touch, but can't really protect against charging at very low temperatures. It seems mainly to protect against cell overheating.

The way the voltage booster is controlled by software is odd, but presumably more versatile. It appears to be using a fixed voltage and a low value resistor in series with the LEDs to set the current.

One good thing about the pandemic and the flurry of dubious sterilising products is that the development of UVC sterilising LEDs has been moved forward significantly by creating a huge market for them.


If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm
This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty.


#ElectronicsCreators