Shielding, Grounding, Noise Suppression, etc. - Revision history

129.105.69.43: /* Grounding Considerations */

2006-10-09T17:29:09Z

Grounding Considerations

← Older revision		Revision as of 12:29, 9 October 2006
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	*Another good thing to do is to isolate our motor/actuator circuit from our logic circuit. We can do this with an '''opto-isolator''' which uses an [[Diodes_and_Transistors#Photo_Transistor \| optical emitter/detector pair]] to send signals back and forth between the separated circuits.		*Another good thing to do is to isolate our motor/actuator circuit from our logic circuit. We can do this with an '''opto-isolator''' which uses an [[Diodes_and_Transistors#Photo_Transistor \| optical emitter/detector pair]] to send signals back and forth between the separated circuits.

	Photo of an opto-isolator:
	[[Image:optoisolator_photo.jpg\|150px]]

	==Minimizing Electro-Magnetic Interference (EMI)==		==Minimizing Electro-Magnetic Interference (EMI)==

Hwang: /* Grounding Considerations */

2006-07-11T17:15:12Z

Grounding Considerations

← Older revision		Revision as of 12:15, 11 July 2006
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	Photo of an opto-isolator:		Photo of an opto-isolator:
	[[Image:optoisolator_photo.jpg]]		[[Image:optoisolator_photo.jpg\|150px]]

	==Minimizing Electro-Magnetic Interference (EMI)==		==Minimizing Electro-Magnetic Interference (EMI)==

Hwang: /* Grounding Considerations */

2006-07-11T17:14:52Z

Grounding Considerations

← Older revision		Revision as of 12:14, 11 July 2006
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	[[Image:bypass_cap.gif]]		[[Image:bypass_cap.gif]]

	*Another good thing to do is to isolate our motor/actuator circuit from our logic circuit. We can do this with an '''opto-isolator''' which uses an [[Diodes_and_Transistors#Photo_Transistor \| optical emitter/detector pair]] to send signals back and forth between the separated circuits		*Another good thing to do is to isolate our motor/actuator circuit from our logic circuit. We can do this with an '''opto-isolator''' which uses an [[Diodes_and_Transistors#Photo_Transistor \| optical emitter/detector pair]] to send signals back and forth between the separated circuits.

			Photo of an opto-isolator:
			[[Image:optoisolator_photo.jpg]]

	==Minimizing Electro-Magnetic Interference (EMI)==		==Minimizing Electro-Magnetic Interference (EMI)==

Hwang: /* Types of Grounds */

2006-07-07T23:20:28Z

Types of Grounds

← Older revision		Revision as of 18:20, 7 July 2006
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	A ground represents a common node, but there are some differences among the types.		A ground represents a common node, but there are some differences among the types.

	The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, ''many circuit diagrams will use this symbol to designate 0V reference even if there is no physical connection with the ground.''		The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, ''many circuit diagrams will use this symbol to designate 0V reference even if there is no physical connection with the ground.''

	The second type, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''		The second type, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''

	The third kind is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most appliances it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.		The third kind is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most high-power appliances, it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.

	===Grounding Considerations===		===Grounding Considerations===

Hwang: /* Types of Grounds */

2006-07-07T23:14:22Z

Types of Grounds

← Older revision		Revision as of 18:14, 7 July 2006
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	The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, ''many circuit diagrams will use this symbol to designate 0V reference even if there is no physical connection with the ground.''		The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, ''many circuit diagrams will use this symbol to designate 0V reference even if there is no physical connection with the ground.''

	The second ~~symbol~~, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''		The second type, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''

	The third kind is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most appliances it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.		The third kind is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most appliances it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.

Hwang: /* Types of Grounds */

2006-07-07T23:14:04Z

Types of Grounds

← Older revision		Revision as of 18:14, 7 July 2006
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	There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''.		There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''.

	~~Each~~ ~~of these symbols~~ represents a common node, but there are some differences.		A ground represents a common node, but there are some differences among the types.

	The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, many circuit diagrams will use this symbol to designate a 0V reference even if there is no physical connection with the ground.		The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, ''many circuit diagrams will use this symbol to designate 0V reference even if there is no physical connection with the ground.''

	The second symbol, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''		The second symbol, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''

	The third ~~symbol~~ is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most appliances it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.		The third kind is known as the '''chassis ground''', and is usually connected to the conducting shell or chassis of that particular piece of equipment. For example, the negative termial of a car battery is wired to the metallic shell of the car. This provides a reference voltage that may or may not be connected to the earth, although for most appliances it usually is. Not connecting the chassis ground to the earth ground can result in a voltage difference between the chassis ground and the earth ground, which leaves the risk of electrical current (including static electricity) finding a path between the chassis and earth through something...or ''someone''. This is the reason why fuel trucks must be grounded while dispensing fuel—the voltage difference can result in a spark and explosion.

	===Grounding Considerations===		===Grounding Considerations===

Hwang: /* Types of Grounds */

2006-07-07T23:12:23Z

Types of Grounds

← Older revision		Revision as of 18:12, 7 July 2006
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	==Grounding==		==Grounding==
	===Types of Grounds===		===Types of Grounds===
	There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''. ~~Their respective symbols are shown below:~~		There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''.

	Each of these symbols represents a common node, but there are some differences.		Each of these symbols represents a common node, but there are some differences.

Hwang: /* Types of Grounds */

2006-07-07T23:12:06Z

Types of Grounds

← Older revision		Revision as of 18:12, 7 July 2006
Line 4:		Line 4:
	===Types of Grounds===		===Types of Grounds===
	There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''. Their respective symbols are shown below:		There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''. Their respective symbols are shown below:

	[[Image:ground_symbols.gif]]

	Each of these symbols represents a common node, but there are some differences.		Each of these symbols represents a common node, but there are some differences.

Hwang at 19:17, 29 June 2006

2006-06-29T19:17:03Z

← Older revision		Revision as of 14:17, 29 June 2006
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	==Grounding==		==Grounding==
	===Types of Grounds===		===Types of Grounds===
	There are generally three types of ~~gounds~~: '''earth ground''', '''signal ground''', and '''chassis ground'''. Their respective symbols are shown below:		There are generally three types of grounds: '''earth ground''', '''signal ground''', and '''chassis ground'''. Their respective symbols are shown below:

	[[Image:ground_symbols.gif]]		[[Image:ground_symbols.gif]]
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	Each of these symbols represents a common node, but there are some differences.		Each of these symbols represents a common node, but there are some differences.

	The '''earth ground''' denotes a physical connection to the earth, which is ~~conventially~~ defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, many circuit diagrams will use this symbol to designate a 0V reference even if there is no physical connection with the ground.		The '''earth ground''' denotes a physical connection to the earth, which is conventionally defined to be 0 volts. On electrical appliances, this is the third pin on the power plug. However, many circuit diagrams will use this symbol to designate a 0V reference even if there is no physical connection with the ground.

	The second symbol, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''		The second symbol, the '''signal ground''', is used as a reference for data transmission lines. The signal ground is generally ''not'' connected to the earth to isolate it from electrical noise and interference from electric currents and fields in the earth. Thus, ''there is often a significant voltage difference between the signal ground and the earth ground.''
Line 29:		Line 29:

	==Minimizing Electro-Magnetic Interference (EMI)==		==Minimizing Electro-Magnetic Interference (EMI)==
	A changing magnetic field can induce a current that can interfere with your signal. The voltage induced by the magnetic field depends on the rate of change of the magnetic field and the area your ~~ciruict~~ loop encloses:		A changing magnetic field can induce a current that can interfere with your signal. The voltage induced by the magnetic field depends on the rate of change of the magnetic field and the area your circuit loop encloses:

	<math>V_{noise}=A(dB/dt)</math>		<math>V_{noise}=A(dB/dt)</math>

Hwang: /* Minimizing Electro-Magnetic Interference (EMI) */

2006-06-29T16:46:56Z

Minimizing Electro-Magnetic Interference (EMI)

← Older revision		Revision as of 11:46, 29 June 2006
Line 43:		Line 43:
	*use short lead wires		*use short lead wires
	*use [http://en.wikipedia.org/wiki/Twisted_pair twisted pair leads].		*use [http://en.wikipedia.org/wiki/Twisted_pair twisted pair leads].
			*use shielded cable with the shield attached to the chassis at both ends.
	*use shielded cale