1. Unit Standard 26119 4 credits 7 weeks
Construct and report on the performance of a simple electronic programmable circuit
4 credits
7 weeks
(wk 3 ~ wk 9)

2. Work in pairs
Assessed individually
All students work on the same project – greenhouse control system
Part One – basic knowledge & skill testing
Part Two – project work
LOG BOOK – sketches, diagrams, schematics, photos, etc.

3. Greenhouse Controller
The system is required to monitor two variables to ensure that the tomato crop thrives in the best possible conditions of temperature, light level or humidity.
It will respond to critical values and initiate a reaction using a suitable transducer (eg LED, motor, sound, etc.)

4. IN5404
.01uF
330
BC547
BD139

7. The LED turns on when the resistance of the LDR is below 7k ohms.
The fan (motor) turns on when the resistance of the thermistor is below 4800 ohms.
Calculate the size of resistor #2 and #7 that will allow the LED and the fan to be turned on at the desired switch point.
Resistor #4 = 330 ohms
Capacitor = 0.01 uF