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SubSystem : P6

Task Title:
Moisture Detecting

Name:
Op Amp Comparator


OnTrack
equipment you will need:

IP1, P6, OP1 Modules
Bridge Power Base
Component Card
4 x 2mm White Leads
4 x Crocodile Leads
Damp Cloth.

Connecting Subsystems:

1, Place the IP1, P6 and OP1 modules onto the Bridge Power Base (see Fig 6.). Connect up the OnTrack module to hold these down.

2, Use two white leads to connect the IP1 module to the 500K Ohm Variable Resistor.

3, Use two white leads to connect OP1 to the L.E.D. as indicated.

4, Connect two crocodile leads from the other connections on IP1 to the edge of a damp piece of rag. Place the clips approximately 4 cm apart.

5,Connect the meter using two more crocodile clips and set it on the 20v range.

6,Check your wiring is accurate and then connect the 9 volt power supply.

 

 

Testing and Investigating:

1, Rotate the 500K Ohm Variable Resistor until the L.E.D. just comes on.

2, Write down the reading shown on the meter. This level is the voltage required to trigger the Op. Amp. Comparator and turn the output on.

3, Remove one of the crocodile clips and now place it so that it is 6cm away from the other clip. The L.E.D. should now be off. What voltage is now shown on the meter?

4, Adjust the 500K resistor until the L.E.D. just lights. You have now reset your dampness indicator.

5,Where might moisture detectors be used? - What would the probes look like; draw them using CAD?