Traditional hotplates aren’t normally thought of as space or energy hogs. In Black Mesa Labs’ case, however, their hotplate – reasonably sized for most applications at 10” x 10” x 3”– was overkill. Most of their boards are one square inch, so something of that size was both a huge waste of energy, workspace, and the cooling time of 30 minutes or more after use was certainly inconvenient.
As with many things in modern life, Internet shopping came to the rescue in the form of a 40mm diameter 24VDC heating element from Amazon. This little guy was able to reach 200ºC in 90 seconds, which is too fast to reflow their boards. This time, the solution wasn’t readily-available to purchase online, but an elegant solution was implemented using an Arduino Pro (ATmega328) as a pulse-width modulation (PWM) controller. A custom-printed circuit board (PCB) from OSH Park helped finish out the build.
Though the Arduino’s capabilities might have been overkill for this kind of application, it allows for a nice solder reflow heating curve, and could certainly accommodate expansion in the future. The fact that its 2” x 2” physical footprint fit the design nicely, and that they had one available already certainly helped justify using it.
You can see it in action in the video below. Melting starts at around 0:15 on a “Mesa Logic DIP” board.
[h/t Hackaday]