$7 Hakko 907 Soldering Station

Like many of us, Angelo Casimiro (AKA TechBuilder) started out with a regular "plug-and-wait" soldering iron. While these devices work, they take somewhere in the range of 10 minutes to warm up, and then stay at max temp until turned off. Digital soldering irons, however, like the high-quality units made by Hakko, work much better, allowing you to program in a temperature that is maintained automatically.

The potential issue is that with high quality comes high cost, so Casimiro came up with his own DIY solution. His device utilizes a clone of the Hakko 907 handle, which plugs into a custom 3D-printed base unit. Inside, an Arduino Nano supplies the PWM-regulated power to the handle/tip via an IRFZ44N MOSFET, enabling it to maintain the temperature set by a potentiometer. A 16x2 LCD display is implemented for user interface, along with an LED that pulses when it’s providing power to the iron.

The whole thing can reportedly be built for around $7, though this will obviously vary depending on where you buy your components. This number also doesn’t include the ideal 24V, 3A power supply needed for the unit, which you can hopefully repurpose from something else. Code, PCB files, and print files for the enclosure are available in the project write-up, and there’s even a link to buy the PCB directly if you want to get started immediately!