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# circuit report watch

1. i need to do a page report on how this cicuit works

so far i have

A resistor is used to reduce the voltage in a circuit. There is a range of resistors with different resistance values. A colour coding system is used on resistors to determine the resistance value. The voltage, resistance or current can be calculated using voltage (V) = current (A) x resistance (ohms).

A LDR is a resistor which resistance value changes upon the amount of light that falls on it. When there is light shining on it, its resistance is low; when there is no light received, its resistance is high. The potentiometer has three legs one connected to a power source, another to a ground ( point with no voltage or resistance) and another to conductive strip which leads on to other components. By placing a screwdriver in the top it can be twisted to change its resistance therefore determining the current that flows through the circuit. The 100k potentiometer and LDR form a voltage and current divider.

The transistor is used as a switch when a sufficient amount of current is received by the base the transistor will allow the maximum amount of current to flow form the collector tot the emitter, the transistor becomes saturated closing the switch. When there is too little current the switch will be open.

When the switch is closed current can continue to flow to the LED causing it to illuminate. The 270 ohm resistor limits the current in the LED preventing any damage being caused to the LED.

anything else i could add or anything wrong with what i have done???
2. (Original post by cjswhufc)
i need to do a page report on how this cicuit works

so far i have

A resistor is used to reduce the voltage in a circuit. There is a range of resistors with different resistance values. A colour coding system is used on resistors to determine the resistance value. The voltage, resistance or current can be calculated using voltage (V) = current (A) x resistance (ohms).

A LDR is a resistor which resistance value changes upon the amount of light that falls on it. When there is light shining on it, its resistance is low; when there is no light received, its resistance is high. The potentiometer has three legs one connected to a power source, another to a ground ( point with no voltage or resistance) and another to conductive strip which leads on to other components. By placing a screwdriver in the top it can be twisted to change its resistance therefore determining the current that flows through the circuit. The 100k potentiometer and LDR form a voltage and current divider.

The transistor is used as a switch when a sufficient amount of current is received by the base the transistor will allow the maximum amount of current to flow form the collector tot the emitter, the transistor becomes saturated closing the switch. When there is too little current the switch will be open.

When the switch is closed current can continue to flow to the LED causing it to illuminate. The 270 ohm resistor limits the current in the LED preventing any damage being caused to the LED.

anything else i could add or anything wrong with what i have done???
The LDR resistance changes depending on which way up the potential divider is and the other resistors value. But I just think I'm being picky! lol, seems ok mate.

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Updated: November 10, 2008
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