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SubSystem : IP1

Task Title:
Light to Voltage Converter
Name: Potential Divider


OnTrack
equipment you will need:

IP1, OP1 Modules
Bridge Power Base
Component Card
4 x 2mm White Leads
2 x Crocodile Leads
Multimeter
9v Power Supply


Connecting up Subsystems:

1, Place the IP1 and OP1 modules onto the Bridge Power Base (Fig 1.2). Connect up the OnTrack module to hold these down.

2, Use the four white leads (shown black in fig.1.2) to connect module IP1 to the L.D.R. and the 20K ohm variable resistor.

3, Connect the crocodile leads to OP1 and then to the red and black meter leads. Make sure they are the right way round.

4, Turn the multimeter switch to the 20v. (D.C.) position .

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

Testing and Investigating:

Don't forget to write up your method and results afterwards.

6, Place your finger over the L.D.R. and turn the variable resistor until the multimeter displays 0.1 volts.

7, Remove your finger from the L.D.R. and look at the new voltage shown on the multimeter. Has it risen or fallen?

8, With your finger still removed can you adjust the variable resistor to change the output voltage to about 1.2 volts and also 4.5 volts? (These are useful output voltages to have when connecting to other OnTrack sub-systems).


Connecting up further circuits

Try building a heat sensor now.

1, Replace the L.D.R. on the component card with the thermistor below it (You can use the same leads). The potential divider is now being used as a Heat Sensor.

2, To check it out, raise the temperature by placing your fingers around the Thermistor or by breathing gently on it . Notice the change in voltage shown on the multimeter. Has it risen or fallen as the temperature increased? (You may need to adjust the variable resistor too). When you have done this draw this new circuit and write up your results.

3, Look at some other Input potential divider circuits in the SubSystem Info Links at the top and try to model some of these. You will need the same four white leads as before and possibly two more 2mm leads with crocodile clips if you make the moisture or angle sensor.