A fan to take away fumes is a useful factor to have when soldering, even higher is a fan furnished with a filter. Higher nonetheless is a fan that prompts solely when the iron is in use, turning off when the iron is in its stand. Now that’s useful!

[Petteri Aimonen] made precisely such a tool when he observed his JBC BT-2BWA soldering station may detect when the iron is faraway from its stand, and point out its working mode through standing LEDs. Broadly talking, when the iron is faraway from its cradle the inexperienced “in use” LED is on. By turning the fan on each time that LED is lit (and turning it off when it turns into unlit), fume extraction will get a little bit extra elegant and environment friendly.

As an alternative of tapping instantly into the soldering station’s {hardware} to detect the LED’s state, [Petteri] went for a totally noninvasive resolution that made good use of some spare elements and a small little bit of copper-clad board. The PCB is nothing greater than piece of copper-clad board with lands scratched out with a pastime knife.

This tiny board sits atop the soldering station, parking a photodiode instantly above the “in use” LED. The circuit is an easy comparator whose output controls fan energy through a MOSFET, and a top-facing LED gives as a replica “in use” indicator, for the reason that unique is hidden underneath the tiny board.

Even for one-off designs like this, making a PCB structure in an EDA program like KiCad continues to be value doing as a result of one can use it to scratch out lands on a copper-clad board, a approach with similarities to Manhattan-style circuit building.