LDR 2 = EMPTY This will sense when the dispenser is empty.
Indicate on the diagram below where LDR 1 and LDR 2 will be located.
Complete the flowchart below with appropriate missing statements.
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| LIGHT / DARK SENSOR QUESTION |
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| PDF FILE - CLICK HERE FOR PRINTABLE VERSION OF EXERCISE SHOWN BELOW |
| Below is a typical chocolate bar dispenser. It includes a light sensor that detects when the dispenser needs filling. |
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| 1. The circuit diagram below is incomplete. Add all the missing components and explain how the circuit works. Include the following components: 1 LDR, 2 fixed resistors, 1 npn transistor and a relay that is energised when light is sensed. |
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| POSSIBLE ANSWER BELOW |
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| 2. The circuit/dispenser designer has recently improved the design of the dispenser and wants to use to LDRs. |
| LDR 1 = LOW This will sense when there are five products left in the
dispenser LDR 2 = EMPTY This will sense when the dispenser is empty. Indicate on the diagram below where LDR 1 and LDR 2 will be located. |
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| 3. A mechanism has been added to the drawer. This moves the drawer forwards and backwards to allow chocolate to be removed from the drawer. Add a suitable mechanism to the incomplete drawing below. Label your diagram |
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| POSSIBLE ANSWER BELOW |
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| 4. Add notes explaining how the mechanism works. |
| 5. When there are
only five chocolate bars left in the dispenser the low warning light
should light. This allows staff in the shop to fill up the machine. When
the dispenser is empty the empty warning light is turned on and an alarm
sounds. Complete the flowchart below with appropriate missing statements. |
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| POSSIBLE ANSWER BELOW |
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