Weekly Project: Follow Me--the Mobile Beverage Cooler

Step 3 Looking for PIRfection

Each PIR sensor needs to be modified for driving a relay switch. Instructions for this modification are supplied with each surplus sensor. Use wire leads approximately 12 inches long for this modification.

The control wires for each sensor are routed out the screw hole in the case back. These wires will be added to the relay circuit that you will be building in the next step.

It's a good idea to test the operation of the sensor at this time (see NOTE below). Temporarily connect the two control wires to an LED with a current-limiting resistor. Install a 9V battery and wave your in front of the sensor. The LED should light for approximately two seconds.

If the operation tests OK, the modified sensors are mounted upside down on the top of the tank. This orientation will ensure that the optimal angle of coverage for each sensor is deflected upwards from the tank. Also, the sensors' coverage should have a slight overlap along the centerline of the tank's cross section.

NOTE: These PIR Sensors are surplus equipment. As such, they are sold "as is" and there is a chance that a sensor might not work in this modified capacity.