There is a certain sense of accomplishment one gets when building their own tools. This is what [Alejandro Velazquez] was going for when he built his own soldering station. Sure you can get a decent station for a pittance on Amazon, or eBay. You can even build your own microprocessor controlled station. [Alejandro] is currently interested in analog electronics, so he went that route to build his own closed-loop station.
The handle is a 50 watt, 24-volt affair with a thermocouple. You can find this handle on many Hakko 907 clone soldering stations, often referred to as the 907A. The station itself is completely analog. A triac switches the current going to the heater. The triac is controlled by a PWM signal. The PWM itself is generated and regulated by an LM324 quad op-amp, which is the heart of the station. The op-amp compares the setpoint with the current temperature read from the soldering handle’s thermocouple, then adjusts the duty cycle of the PWM signal to raise, or lower the temperature.
It’s a classic control system, and the schematic is definitely worth checking out if you want to understand how op-amps can be used to create complex operations.
You can find plenty more information on analog electronics right here on Hackaday — we’ve covered thermocouple amplifiers, as well as instrumentation amps. If you’re more of a digital man, check out this Arduino controlled soldering station!




Over the last decade or so things have changed. China got involved, and suddenly there were cheap lasers on the market. Currently, there are several low-cost laser models available in various power levels. The most popular is the smallest – a 40-watt model, dubbed the K40. There are numerous manufacturers and there have been many versions over the years. They all look about the same though: A blue sheet metal box with the laser tube mounted along the back. The cutting compartment is on the left and the electronics are on the right. Earlier versions came with Moshidraw software and a parallel interface.


On the hardware side, the heart of the OTTO is a Raspberry Pi 3. The all-important audio interface is a Fe-Pi Audio Z V2, though a USB interface can be used. The 48 switches and four rotary encoders are wrangled by a pair of Arduino pro micros which pass the data on to the Pi. Data is related to the user through a 320×200 LCD.