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Title: Computer Input and Output Devices
Question: With the increased use of computers on street rods, it is helpful to understand some of the terminology and electrical components. Most of these components are related to the input, process, and output model discussed in an earlier Q and A segment. What are some of the more common input and output electrical components or devices used on computer systems for street rods today?
Question: With the increased use of computers on street rods, it is helpful to understand some of the terminology and electrical components. Most of these components are related to the input, process, and output model discussed in an earlier Q and A segment. What are some of the more common input and output electrical components or devices used on computer systems for street rods today?
Answer: Referring to the illustration on the left, there are five types of electrical input devices shown on the left, and six types of electrical output devices shown on the right. The exact devices used will depend upon the manufacturer and year of the computer system.
INPUTS
The first input is called a potentiometer. This device is used to change the voltage drop in relation to some form of mechanical movement. A good example of a potentiometer is the throttle position sensor. It is used to change the voltage drop as the throttle position is changed. This signal is then sent to the computer as one
of the input sensors.
A second type of electrical input device is called a variable resistor, also called a Thermistor. It is able to change its resistance based upon the temperature of an object. This type of sensor is used to sense the temperature of the engine coolant. As the coolant temperature changes, the resistance in the Thermistor changes. This signal is then sent to the computer.
A third type of electrical input device is called a magnetic pickup. It is designed to measure the speed of a rotating shaft. In operation, a small magnet is placed on a rotating shaft. As it spins, the magnet induces a voltage in the coil of wire. This produces a charge or pulse of electricity which acts as an input signal to the computer. This type of electrical input device is often used to determine how fast the vehicle is going by placing this magnetic pickup on the output shaft of a transmission.
A fourth type of electrical input is called the voltage generator. This type of electrical input device is able to produce a voltage based on such things as the amount of oxygen in the exhaust. It is mounted in the exhaust flow from the engine. Based on the amount of oxygen in the exhaust, it can determine a lean or rich air-fuel mixture. A lean mixture produces a lower voltage while a richer mixture produces a higher voltage. This voltage signal is then sent as an input to the computer.
A fifth type of electrical input device is the switch. It is used to indicate an electrical off or on condition. For example, at times the computer needs to determine if the A/C is on or off. The on or off condition is determined by the position of the switch and act as an input to the computer.
OUTPUTS
The first type of electrical output device is called the relay. It uses a small coil of wire to control the opening and closing of a second electrical circuit. A good example of this type of output is the cooling fan relay. Based upon data from the inputs, the computer turns the cooling fan on and off at the correct time with this relay.
Another type of electrical output device is called the solenoid. This item uses the magnetism in a coil of wire to move a rod or metal in its center. The most common use for this type of electrical output device is the action of a port fuel injector. Based on sevaral input signals, the computer knows exactly when to send a signal to each port fuel injector to inject fuel at the correct time and at the correct amount.
The servomotor receives a computer signal to move or turn something. Such a motor is often used to position the throttle which sets the idle of the engine. The exact position of the idle servomotor will be determined by several of the electrical inputs to the computer.
Another type of electrical output device is the lamp or an information display on the dashboard. Based on the inputs, the computer will send a voltage signal to the various lights and other information on the dashboard of the vehicle.
The switching transistor acts much the same way as a relay, but without moving parts. The computer will energize the transistor bottom wire (base) so that a circuit with higher current can be controlled (the left and right wires).
The final type of electrical output device shown is the transformer. The computer sends electricity to the left coil, which produces a higher voltage in the right coil. The most common use for this type of electrical output device is the ignition coil used to fire the spark plugs. These coils change the 12 volt battery voltage to 60,000 volts or higher to fire the spark plugs at the precise time needed for the most efficient combustion.
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INPUTS
The first input is called a potentiometer. This device is used to change the voltage drop in relation to some form of mechanical movement. A good example of a potentiometer is the throttle position sensor. It is used to change the voltage drop as the throttle position is changed. This signal is then sent to the computer as one
of the input sensors.
A second type of electrical input device is called a variable resistor, also called a Thermistor. It is able to change its resistance based upon the temperature of an object. This type of sensor is used to sense the temperature of the engine coolant. As the coolant temperature changes, the resistance in the Thermistor changes. This signal is then sent to the computer.
A third type of electrical input device is called a magnetic pickup. It is designed to measure the speed of a rotating shaft. In operation, a small magnet is placed on a rotating shaft. As it spins, the magnet induces a voltage in the coil of wire. This produces a charge or pulse of electricity which acts as an input signal to the computer. This type of electrical input device is often used to determine how fast the vehicle is going by placing this magnetic pickup on the output shaft of a transmission.
A fourth type of electrical input is called the voltage generator. This type of electrical input device is able to produce a voltage based on such things as the amount of oxygen in the exhaust. It is mounted in the exhaust flow from the engine. Based on the amount of oxygen in the exhaust, it can determine a lean or rich air-fuel mixture. A lean mixture produces a lower voltage while a richer mixture produces a higher voltage. This voltage signal is then sent as an input to the computer.
A fifth type of electrical input device is the switch. It is used to indicate an electrical off or on condition. For example, at times the computer needs to determine if the A/C is on or off. The on or off condition is determined by the position of the switch and act as an input to the computer.
OUTPUTS
The first type of electrical output device is called the relay. It uses a small coil of wire to control the opening and closing of a second electrical circuit. A good example of this type of output is the cooling fan relay. Based upon data from the inputs, the computer turns the cooling fan on and off at the correct time with this relay.
Another type of electrical output device is called the solenoid. This item uses the magnetism in a coil of wire to move a rod or metal in its center. The most common use for this type of electrical output device is the action of a port fuel injector. Based on sevaral input signals, the computer knows exactly when to send a signal to each port fuel injector to inject fuel at the correct time and at the correct amount.
The servomotor receives a computer signal to move or turn something. Such a motor is often used to position the throttle which sets the idle of the engine. The exact position of the idle servomotor will be determined by several of the electrical inputs to the computer.
Another type of electrical output device is the lamp or an information display on the dashboard. Based on the inputs, the computer will send a voltage signal to the various lights and other information on the dashboard of the vehicle.
The switching transistor acts much the same way as a relay, but without moving parts. The computer will energize the transistor bottom wire (base) so that a circuit with higher current can be controlled (the left and right wires).
The final type of electrical output device shown is the transformer. The computer sends electricity to the left coil, which produces a higher voltage in the right coil. The most common use for this type of electrical output device is the ignition coil used to fire the spark plugs. These coils change the 12 volt battery voltage to 60,000 volts or higher to fire the spark plugs at the precise time needed for the most efficient combustion.
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