A Simple Soft Power Switch Using Common Modules

If you want to easily control the power in a circuit, you’ll probably reach for the classic toggle switch. While there’s certainly nothing wrong with that, physical toggles are a bit dated at this point. A soft power switch that turns your gadget on and off at the tap of a finger is far more 21st century. You might think this kind of modern trickery is too difficult to implement on a DIY project, but as [Sasa Karanovic] shows, it’s actually a lot easier than you might think.

Now to be fair, that wasn’t actually his goal. All [Sasa] was trying to do was come up with a slick way to control the LED lighting in his 3D printer enclosure. Which, as you can see in the video below, he accomplished. But the hacked together circuit he used to do it could easily be adapted for other electronic projects. If you’re using a LM2596 DC-DC converter module to power your gadget, you can add a touch sensitive soft switch for literally pennies.

The trick is utilizing the enable pin on the LM2596. The common buck converter modules tie this pin to ground so the regulator is always enabled, but if you lift the pin off the PCB and connect it to the output of a TTP223 capacitive touch sensor, you can simply tap the pad to control the regulator. Power for the touch sensor itself is pulled from the input side of the regulator, so even when the power is cut off downstream, the sensor is still awake and can kick the chip back into gear when you need it.

If you’re not interested in touch control, you could try connecting the enable pin on the regulator to an ESP8266 and making a cheap Internet-controlled DC power supply. Continue reading “A Simple Soft Power Switch Using Common Modules”