Modifying Cheap PIR Motion Sensor to Work at 3.3V

Some of these modules come with pins soldered in that top right corner, so you don’t have to solder anything. You would simply connect a jumper wire to that pin that is highlighted in red (see Figure below). With my particular sensor I had to solder a small wire.
Here’s how it looks, now if you supply 3.3V through that red wire your module works at 3.3V.