In our article Hacked PIR Sensor we showed how a very cheap battery powered PIR motion sensing lamp could be used in place of a more expensive PIR motion sensors in a range of projects – primarily to switch a relay which can in turn switch lighting, appliances, and pretty much anything else.

Pictured above is an alternative we purchased from Sure Electronics, priced at around only £3 delivered to the UK.

Taking a 4.5 to 20 VDC input, one big advantage of this sensor is that it gives a high signal (+3.3V) when motion is detected (much like this KC7783R PIR module) as opposed to the standard low signal (0V) when motion is detected of typical burglar alarm type PIR sensors. This makes it much simpler to use this type of PIR sensor to do things when motion is detected.

What makes it particularly useful is that it has a built in 5 to 200 seconds timer, so the user can set up this PIR module to supply an output to come on for however long they want after motion has been detected. The sensitivity of the unit can also be adjusted to detect human motion at a maximum of from 3 to 7 metres distance with a detection angle of 110 degrees.

Pictured above is a very simple circuit which will see the red LED turned on when motion is detected, and off the rest of the time. If the connections to the LED and resistor are instead connected to the coil of a relay, anything else could be switched by this module.

Pictured above is a schematic of the way we have incorporated this PIR module into our solar powered LED shed lighting so that the lights come on automatically when someone enters the shed and turns then off very soon after they leave. No longer will lights left on drain the battery.

This PIR module weighs in at just over 30g, and is a tiny 32 x 24 x 25mm in size. It also has a quiescent current (the current when the PIR sensor is powered and waiting to detect motion) of just 60uA. Therefore it can be used in battery powered applications without draining the battery too rapidly whether it be 3 or 4 AA cells connected in series, a 9V battery, or a 12V battery.

Buy a PIR Module Now

Typically coming from China or Hong Kong, these PIR modules typically take around 3 weeks to be arrive in the UK after purchase. There is now a really good range of similar units available to choose from with prices from just £1.50 delivered to the UK, so click here to view the selection: PIR modules.