Here’s another little project I’ve been working on recently. It’s a portable solder fume extractor built from a recycled 80mm psu fan. Previously I had used the fan hooked up to the 12v rail of a computer power supply, but due to a recent move I wanted to build something a little more lightweight and portable. For dramatic effect I call it the Solder Sniffer 9000. It’s pretty simple in its design. There’s basically two main circuits, a charging circuit and a voltage booster circuit.
The charge circuit consists of a micro usb port, an MCP73831 li-ion charge controller from Microchip, and a protected 18650 li-ion battery. I used the schematics for this Adafruit charger to get a start on the initial design: Downloads | Adafruit MicroLipo and MiniLipo Battery Chargers | Adafruit Learning System. It basically follows the application circuit from the datasheet, except Adafruit uses a nifty way of charlieplexing the status leds to provide both a red(charging) and green(charged) status indicator. Here’s the finished schematic for the charge circuit:
The boost circuit was needed to boost the 2.6-4.2 volts output from the 18650 to the 12volts expected by the fan. For the booster circuit I used the Semtech SC4503 step-up switching regulator. I chose this regulator because it seemed to have a nice compromise between peak efficiency while also meeting the load current demands of my particular fan. The datasheet provided many application circuit examples, so I adapted one that was most similar to my needs and used it. Here’s the finished circuit for the boost converter:
And here’s the finished PCB:
Here’s the finished product extracting some fumes:
The backside with an activated carbon filter:
Of course I haven’t really had many chances to use it yet, but I’m hoping it provides at least a little relief from fumes in the projects to come.