Signal Sources and Amplifiers - Revision history

Boris at 00:36, 20 May 2016

2016-05-20T00:36:48Z

Oliver at 04:36, 7 November 2014

2014-11-07T04:36:37Z

Oliver at 04:34, 7 November 2014

2014-11-07T04:34:15Z

Oliver at 04:30, 7 November 2014

2014-11-07T04:30:04Z

Oliver at 04:23, 7 November 2014

2014-11-07T04:23:14Z

Oliver: /* Single Ended-Floating */

2014-11-07T04:13:58Z

‎Single Ended-Floating

Oliver: /* Signal Sources */

2014-11-07T04:08:54Z

‎Signal Sources

Oliver: /* Signal Sources */

2014-11-07T04:07:45Z

‎Signal Sources

Boris: /* Single ended-Floating */

2013-09-20T06:53:37Z

‎Single ended-Floating

Boris: /* Single ended-Floating */

2013-09-20T06:44:40Z

‎Single ended-Floating

← Older revision		Revision as of 00:36, 20 May 2016
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	* Zcm is zero: The signal source becomes “Grounded source”. One terminal carries the signal and the other is connected to ground or 0 volts. An example is an AC powered instrument like a signal generator.		* Zcm is zero: The signal source becomes “Grounded source”. One terminal carries the signal and the other is connected to ground or 0 volts. An example is an AC powered instrument like a signal generator.
	* Zcm is nonzero: This represents most practical situations. This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.		* Zcm is nonzero: This represents most practical situations. This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.
−

@@ Line 101: / Line 101: @@
 There are three distinct conditions:
-* Zcm is infinite: The signal source becomes a “Floating  source”. Examples include pH electrode, pH/Ion selective electrode, piezo electric sensor, Thermocouple, and Battery or battery powered instrument or meter.
+* Zcm is infinite: The signal source becomes a “Floating source”. Examples include pH electrode, pH/ion selective electrode, piezo electric sensor, thermocouple, and battery or battery powered instrument or meter.
-* Zcm is zero: The signal source becomes “Grounded source”.  One terminal carries the signal and the other is connected to ground or 0 volts. An example is an AC powered instrument like a signal generator.
+* Zcm is zero: The signal source becomes “Grounded source”. One terminal carries the signal and the other is connected to ground or 0 volts. An example is an AC powered instrument like a signal generator.
-* Zcm is nonzero: This represents most practical situations.  This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.
+* Zcm is nonzero: This represents most practical situations. This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.

@@ Line 101: / Line 101: @@
 There are three distinct conditions:
+* Zcm is infinite: The signal source becomes a “Floating  source”. Examples include pH electrode, pH/Ion selective electrode, piezo electric sensor, Thermocouple, and Battery or battery powered instrument or meter.
-* Zcm is infinite: The signal source becomes a “Floating  source”.
+* Zcm is zero: The signal source becomes “Grounded source”.  One terminal carries the signal and the other is connected to ground or 0 volts. An example is an AC powered instrument like a signal generator.
-Examples:
 pH electrode
 pH/Ion selective electrode
 piezo electric sensor
 Thermocouple
 Battery or battery powered instrument or meter
-−
 * Zcm is zero: The signal source becomes “Grounded source”.  One terminal carries the signal and the other is connected to ground or 0 volts.
-Examples:
 AC powered instrument like a signal generator
-−
 * Zcm is nonzero: This represents most practical situations.  This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.

@@ Line 72: / Line 72: @@
 *AC powered transducer
 *Chromatography detector
 ===Balanced - Floating===
@@ Line 83: / Line 84: @@
 ===Balanced - Grounded with Common mode voltage===
-In this configuration the two terminals are both active and have equal impedance to a common point which is connected to ground via a CM voltage. The voltage on the two terminals moves in different directions in relation to the common point.  The CM voltage can either be Zero when the center point is directly grounded, it can be at a fixed DC value or can result from unintentional connection to ground.
+In this configuration the two terminals are both active and have equal impedance to a common point which is connected to ground via a CM voltage. The voltage on the two terminals moves in different directions in relation to the common point.  The CM voltage can be zero when the center point is directly grounded, it can be at a fixed DC value or can result from unintentional connection to ground.
 Examples of Balanced floating Source with common mode voltage
@@ Line 93: / Line 94: @@
-Characteristics of electrical signal sources in a Chemistry analytical laboratory.
+Characteristics of electrical signal sources in a chemistry analytical laboratory.
 Examples:
 ====Single Ended Referenced to Ground====
-In this case one terminal contains the signal and the other terminal is referenced to ground. This reference to ground can be modelled by an Impedance and a series voltage source. These are referred to as Common Mode Impedance Zcm and Common Mode voltage Vcm
+In this case one terminal contains the signal and the other terminal is referenced to ground. This reference to ground can be modelled by an Impedance and a series voltage source. These are referred to as Common Mode Impedance (Zcm) and Common Mode voltage (Vcm)
 There are three distinct conditions:
 Zcm is infinite: The signal source becomes a “Floating  source”.
 Examples:
 pH electrode
@@ Line 108: / Line 110: @@
 Battery or battery powered instrument or meter
-Zcm is zero: The signal source becomes “Grounded source”.  One terminal carries the signal and the other is connected to ground or 0 volts.
+* Zcm is zero: The signal source becomes “Grounded source”.  One terminal carries the signal and the other is connected to ground or 0 volts.
 Examples:
 AC powered instrument like a signal generator
-Zcm is nonzero: This represents most practical situations.  This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.
+* Zcm is nonzero: This represents most practical situations.  This term is sometimes introduced as a necessary component in the measurement system but typically it represents a “noise” element to be avoided by the choice of an appropriate amplifier input configuration.

@@ Line 26: / Line 26: @@
 In its most general form a signal source can be described by the diagram Generalised Signal source
 The 4 classes are listed and discussed below:
@@ Line 33: / Line 34: @@
 [[File:New SE Floating.svg|200px|thumb|left|SE Floating]]
-Single Ended Floating signals appears between the two terminals of the signal source. Either of these terminal can be grounded without altering the potential across the two terminals. All signal sources can be regarded as Voltage or Current sources as defined in Nortons Theorem.
+Single Ended Floating signals appears between the two terminals of the signal source. Either of these terminals can be grounded without altering the potential across the two terminals. All signal sources can be regarded as Voltage or Current sources as defined in Nortons Theorem.
 http://en.wikipedia.org/wiki/Norton%27s_theorem.
@@ Line 39: / Line 40: @@
 In an analytical laboratory:
-Typical voltage ranges: 1uV (thermocouples) to 30,000Volts (capillary electrophoresis high voltage supplies) - internal impedances are typically low.
+Typical voltage ranges: 1 uV (thermocouples) to 30,000 volts (capillary electrophoresis high voltage supplies) - internal impedances are typically low.
-Typical current ranges: <1pA (small amperometric electrode) >10Amps (high power potentiostat) - internal impedances are typically high.
 Signal frequency content:  DC to MHz
-An ideal voltage Source has a near zero internal impedance. An accurate reading can only be obtained with a measuring circuit whose own internal resistance is much higher than the source resistance of the source. Voltmeters therefore need to have a high internal resistance - ideally infinite.
+An ideal voltage source has a near zero internal impedance. An accurate reading can only be obtained with a measuring circuit whose own internal resistance is much higher than the source resistance of the source. Voltmeters therefore need to have a high internal resistance - ideally infinite.
-An ideal current Source has a near infinite internal impedance. In this case to measure the source current the measurement impedance should be very low.  Ammeters therefore need to have a low internal resistance - ideally zero.
+An ideal current source has a near infinite internal impedance. In this case to measure the source current the measurement impedance should be very low.  Ammeters therefore need to have a low internal resistance - ideally zero.
 '''Examples'''
 '''SE Voltage sources'''
 *Battery - very low internal resistance
@@ Line 57: / Line 61: @@
 *Electrochemical sensor - high internal resistance
 *Piezo-Electric sensor - very high resistance
 ===Single ended - Grounded with Common mode voltage===
 In this configuration one of the terminals is effectively connected to ground via another signal source - called a "Common Mode Voltage". This CM Voltage may be intentional but in most cases it is unintentional and can present a significant problem in the measurement of the signal of interest. In this case the effective signal occurs across the two terminals of the source and is made up of the signal with the CM voltage added to it as shown below.
 A special but common case of this configuration is when the CM voltage is zero and one of the terminals is effectively connected to ground.
 Examples of Single Ended Grounded with common mode
@@ Line 72: / Line 75: @@
 ===Balanced - Floating===
 In this configuration the two terminals are both active and have equal impedance to a common point which is floating and unconnected to ground. The voltage on the two terminals moves in different directions in relation to the common point.
 Examples of Balanced floating Source
@@ Line 79: / Line 80: @@
 *Linear variable differential transformer (LVDT)
 *Center tapped Transformer
 ===Balanced - Grounded with Common mode voltage===
 In this configuration the two terminals are both active and have equal impedance to a common point which is connected to ground via a CM voltage. The voltage on the two terminals moves in different directions in relation to the common point.  The CM voltage can either be Zero when the center point is directly grounded, it can be at a fixed DC value or can result from unintentional connection to ground.
 Examples of Balanced floating Source with common mode voltage
 *Four Arm Wheatstone Bridge with line powered supply
 *Differential output Operational Amplifier
 ==Source Characteristics==

@@ Line 25: / Line 25: @@
 http://en.wikipedia.org/wiki/Electrical_impedance
-In its most general form a signal source can be described by the following diagram:
+In its most general form a signal source can be described by the diagram Generalised Signal source
 The 4 classes are listed and discussed below:
-===Single ended-Floating===
+===Single Ended-Floating===
 [[File:xxxxxxxx.svg|200px|thumb|left|SE Floating]]

@@ Line 11: / Line 11: @@
 [[File:New general ss.svg|200px|thumb|left|Generalised Signal source]]
-There are 4 types or classes of electical signal sources which occur in various experimental situations. It is important to understand the characteristcs of these signal sources in order that they can be matched to the correct amplifier/recording system without degrading the  accuracy of the measurement.
+There are 4 types or classes of electrical signal sources which occur in various experimental situations:
 NOTE: In discussing the characteristics of signal sources reference will be made to "Source Impedance" which in its most general form consists of a combination of 3 electrical elements: Resistance,Inductance and Capacitance.
@@ Line 37: / Line 43: @@
 Signal frequency content:  DC to MHz
-An ideal voltage Source has a near zero internal impedance. An accurate reading can only be obtained with a measuring circuit whose own internal resistance is much higher than the source resistance of the source. Voltmeters therefore need to have a high internal reistance - ideally infinite.
+An ideal voltage Source has a near zero internal impedance. An accurate reading can only be obtained with a measuring circuit whose own internal resistance is much higher than the source resistance of the source. Voltmeters therefore need to have a high internal resistance - ideally infinite.
 An ideal current Source has a near infinite internal impedance. In this case to measure the source current the measurement impedance should be very low.  Ammeters therefore need to have a low internal resistance - ideally zero.
@@ Line 48: / Line 54: @@
 '''SE Current sources'''
-*Silicon detector - high internal reisitance
+*Silicon detector - high internal resistance
 *Electrochemical sensor - high internal resistance
 *Piezo-Electric sensor - very high resistance
@@ Line 75: / Line 81: @@
 ===Balanced - Grounded with Common mode voltage===
-In this configuration the two terminals are both active and have equal impedance to a common point which is connected to ground via a CM voltage. The voltage on the two terminals moves in different directions in relation to the common point.  The CM votage can either be Zero when the center point is directly grounded, it can be at a fixed DC value or can result from unintentional connection to ground.
+In this configuration the two terminals are both active and have equal impedance to a common point which is connected to ground via a CM voltage. The voltage on the two terminals moves in different directions in relation to the common point.  The CM voltage can either be Zero when the center point is directly grounded, it can be at a fixed DC value or can result from unintentional connection to ground.
 Add picture of single ended with common mode voltage.
-Examples of Balanced floating Source with coomon mode voltage
+Examples of Balanced floating Source with common mode voltage
 *Four Arm Wheatstone Bridge with line powered supply
 *Differential output Operational Amplifier