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GCSE Coursework 44302

2012-05-15T15:25:13Z

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	# System Diagram		# System Diagram
-	# ~~Labeled~~ Circuit Diagram	+	# Labelled Circuit Diagram
	# Circuit Board Photos		# Circuit Board Photos
	# Proof of Activity Photos		# Proof of Activity Photos

ELEC3

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	* Get all your subsystems to work together.		* Get all your subsystems to work together.
	* Produce a complete circuit diagram.		* Produce a complete circuit diagram.
-	* Each component is ~~labeled~~ C1, R1, C2, R2, etc to make it easy to write about the circuit.	+	* Each component is labelled C1, R1, C2, R2, etc to make it easy to write about the circuit.

	'''B d - Explain in detail how the whole system works.'''		'''B d - Explain in detail how the whole system works.'''

Circuit and Packet Switching

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	There is a great deal of confusion about packet terminology. Many packets should not be called packets! TCP segments are wrapped or encapsulated inside IP packets. The IP packets are encapsulated inside Ethernet frames.		There is a great deal of confusion about packet terminology. Many packets should not be called packets! TCP segments are wrapped or encapsulated inside IP packets. The IP packets are encapsulated inside Ethernet frames.

-	To grasp the idea of encapsulation, think of a letter inside an envelope inside a mail sack inside an aircraft. The envelope, the sack and the aircraft all carry addressing information (the pilot knows where to fly to). The sack will be ~~labeled~~ with a sorting office address. The letter carries the street address.	+	To grasp the idea of encapsulation, think of a letter inside an envelope inside a mail sack inside an aircraft. The envelope, the sack and the aircraft all carry addressing information (the pilot knows where to fly to). The sack will be labelled with a sorting office address. The letter carries the street address.

	Internet addressing is also complex in a similar way. There is a MAC address which identifies a local hardware device. There is the IP address which has two portions. The network number identifies the destination network and the host address identifies a machine on the destination network.		Internet addressing is also complex in a similar way. There is a MAC address which identifies a local hardware device. There is the IP address which has two portions. The network number identifies the destination network and the host address identifies a machine on the destination network.

System Synthesis

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	== Information Flows ==		== Information Flows ==

-	The flow of information through a system is shown with ~~labeled~~ arrows. Don't forget the labels. Don't forget the arrow heads to show the direction. The information is carried by currents, voltages, sound waves, ultra-sound, radio waves, pulses of light or by some other method. There are lots of ways to get information from one place to another.	+	The flow of information through a system is shown with labelled arrows. Don't forget the labels. Don't forget the arrow heads to show the direction. The information is carried by currents, voltages, sound waves, ultra-sound, radio waves, pulses of light or by some other method. There are lots of ways to get information from one place to another.

	== Feedback ==		== Feedback ==

Basic Maths

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Calculator Powers of Ten:

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	There seem to be several methods used by different calculator manufacturers to solve powers of 10. Most students should use a low cost scientific calculator. More advanced models can be too hard to use and sometimes are quite non-standard.		There seem to be several methods used by different calculator manufacturers to solve powers of 10. Most students should use a low cost scientific calculator. More advanced models can be too hard to use and sometimes are quite non-standard.

-	Find out how to enter powers of 10 into your calculator. The most obvious way is nearly always wrong! Look for the '''Exp''' button. This is the "Times-ten-to-the" button. Look for the +/- button. This is used to enter things like 10<sup>-9</sup>. If you use the normal minus button, on many calculators, it won't work. On some calculators the '''Exp''' button is ~~labeled~~ '''x10'''	+	Find out how to enter powers of 10 into your calculator. The most obvious way is nearly always wrong! Look for the '''Exp''' button. This is the "Times-ten-to-the" button. Look for the +/- button. This is used to enter things like 10<sup>-9</sup>. If you use the normal minus button, on many calculators, it won't work. On some calculators the '''Exp''' button is labelled '''x10'''

	== Example Calculator Key Presses ==		== Example Calculator Key Presses ==

AM

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	* This circuit uses a source follower to drive an LED.		* This circuit uses a source follower to drive an LED.
	* It is capable, with a heat-sink, of driving a higher power LED.		* It is capable, with a heat-sink, of driving a higher power LED.
-	* Using the ~~labeled~~ component values, a standard 10mA LED should be used.	+	* Using the labelled component values, a standard 10mA LED should be used.
	* Using lenses or fibre optics, a range of several meters is attainable with ease.		* Using lenses or fibre optics, a range of several meters is attainable with ease.
	* The world record for communication using techniques like this is over 100 Miles!		* The world record for communication using techniques like this is over 100 Miles!

ELEC6

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	* Full details of how the system works and the form and style of writing are appropriate.		* Full details of how the system works and the form and style of writing are appropriate.
-	* You need a complete, fully ~~labeled~~ circuit diagram with each component ~~labeled~~ in this style. R1, R2, C2, R3, Etc.	+	* You need a complete, fully labelled circuit diagram with each component labelled in this style. R1, R2, C2, R3, Etc.
	\|		\|
	[[File:Elec6-Bd.gif]]		[[File:Elec6-Bd.gif]]
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	* Screen Shots		* Screen Shots

-	Ensure all diagrams, photos and screen shots are useful. Make sure they are all ~~labeled~~, annotated and explained.	+	Ensure all diagrams, photos and screen shots are useful. Make sure they are all labelled, annotated and explained.
	\|		\|

AM Transmitter

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	* The microphone provides 20 to 40 mV but the modulator needs 2 to 4 Volts.		* The microphone provides 20 to 40 mV but the modulator needs 2 to 4 Volts.
	* The non inverting amplifier has a gain = 1 + 470 / 4.7 = 101.		* The non inverting amplifier has a gain = 1 + 470 / 4.7 = 101.
-	* The two resistors ~~labeled~~ RvDiv form a voltage divider with a 6 Volt output.<br />This allows the op amp to function without a negative power supply.	+	* The two resistors labelled RvDiv form a voltage divider with a 6 Volt output.<br />This allows the op amp to function without a negative power supply.
	* C4 is a decoupling capacitor. It ensures that the 6 Volt DC level is steady without any AC signals present.		* C4 is a decoupling capacitor. It ensures that the 6 Volt DC level is steady without any AC signals present.
	* Rg holds the non inverting input at 6 Volts DC without lowering the input impedance too much.		* Rg holds the non inverting input at 6 Volts DC without lowering the input impedance too much.

Writing Subsystem Specifications

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	# The battery voltage will be 4 to 6 Volts - To be tested with a multimeter when the battery is new and when it's nearly run out.		# The battery voltage will be 4 to 6 Volts - To be tested with a multimeter when the battery is new and when it's nearly run out.
-	# The battery capacity will be 2500mAH - This should be ~~labeled~~ on the battery	+	# The battery capacity will be 2500mAH - This should be labelled on the battery
	# The battery life will be at least 10 hours - To be measured with a clock.		# The battery life will be at least 10 hours - To be measured with a clock.

	[[Category:Project]]		[[Category:Project]]

Karnaugh Maps

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	[[File:Gate-Karnough-1.gif]]		[[File:Gate-Karnough-1.gif]]

-	In this circuit, the AND gates are wired up to DECODE or respond to particular numbers. They are colour coded and ~~labeled~~ to show which number. The rows in the table have matching colour codes. The Boolean expression is also colour coded to show which part of the expression matches each number or row in the table.	+	In this circuit, the AND gates are wired up to DECODE or respond to particular numbers. They are colour coded and labelled to show which number. The rows in the table have matching colour codes. The Boolean expression is also colour coded to show which part of the expression matches each number or row in the table.

	In plain English, the circuit detects 2, 4, 5 or 6.		In plain English, the circuit detects 2, 4, 5 or 6.

Ring Modulator

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	It is possible to use salvaged mains transformers and almost any diode but the quality of the sound effect may not be too good. All four diodes should be of the same type.		It is possible to use salvaged mains transformers and almost any diode but the quality of the sound effect may not be too good. All four diodes should be of the same type.

-	The transformers need to have centre taps on their secondary coils. They might be ~~labeled~~ 240V on the primary and 12 - 0 - 12 on the secondary. Silicon diodes work but germanium diodes (matched if possible) are likely to work much better. This is because germanium diodes have a smaller forward voltage when conducting. Try OA81, 1N34 or 1N270.	+	The transformers need to have centre taps on their secondary coils. They might be labelled 240V on the primary and 12 - 0 - 12 on the secondary. Silicon diodes work but germanium diodes (matched if possible) are likely to work much better. This is because germanium diodes have a smaller forward voltage when conducting. Try OA81, 1N34 or 1N270.

	Good audio transformers should work better than salvaged mains transformers. Much smaller Input 1 and 2 voltages would be needed. For example ...		Good audio transformers should work better than salvaged mains transformers. Much smaller Input 1 and 2 voltages would be needed. For example ...

A2 Microcontroller Test

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	# Microcontrollers with an extra fourth bus are said to have the _________________ architecture.<br /><br /><br />		# Microcontrollers with an extra fourth bus are said to have the _________________ architecture.<br /><br /><br />
	# The control bus above contains two wires. These are <br /><br /><br /> a) The _______________.<br /><br /><br /> b) The __________ / ___________ line.<br /><br /><br />		# The control bus above contains two wires. These are <br /><br /><br /> a) The _______________.<br /><br /><br /> b) The __________ / ___________ line.<br /><br /><br />
-	# Microcontrollers are often ~~labeled~~ SoC. This stands for _____________ ____ _____ ________________.<br /><br />	+	# Microcontrollers are often labelled SoC. This stands for _____________ ____ _____ ________________.<br /><br />
	[10 Marks]		[10 Marks]

	[[Category:Ten Mark Test]]		[[Category:Ten Mark Test]]

PICAXE LEDs

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	\|		\|
	* This causes the program to return to the start.		* This causes the program to return to the start.
-	* The PROGRAM COUNTER is set to the address ~~labeled~~ by start:	+	* The PROGRAM COUNTER is set to the address labelled by start:
	\|}		\|}

PICAXE Introduction

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	* Port B is output only.		* Port B is output only.
	* The ADC inputs are shown.		* The ADC inputs are shown.
-	* There are some power supply connections ~~labeled~~ 5 5 0 0 0 0 9 9.	+	* There are some power supply connections labelled 5 5 0 0 0 0 9 9.
	* The 5 lines carry 5 Volts.		* The 5 lines carry 5 Volts.
	* The 0 lines are the ground connection.		* The 0 lines are the ground connection.

Inverting Amplifier

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	'''Explanation: ''' Operational amplifiers have a very large open loop gain. So if the output is a few volts, the inverting input voltage must be very small (a few microvolts). This voltage is so small, it is called a virtual earth.		'''Explanation: ''' Operational amplifiers have a very large open loop gain. So if the output is a few volts, the inverting input voltage must be very small (a few microvolts). This voltage is so small, it is called a virtual earth.

-	The inverting input, ~~labeled~~ "P", is a Virtual Earth because the voltage here is approximately zero as long as the amplifier is not saturating or limiting.	+	The inverting input, labelled "P", is a Virtual Earth because the voltage here is approximately zero as long as the amplifier is not saturating or limiting.

	== For Maths Experts ==		== For Maths Experts ==

Summing Amplifier

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	* Rf provides negative feedback. The gain of each input depends on Rf and the input resistor.		* Rf provides negative feedback. The gain of each input depends on Rf and the input resistor.

-	The inverting input ~~labeled~~ "P" is a Virtual Earth. The virtual earth comes about as follows ...	+	The inverting input labelled "P" is a Virtual Earth. The virtual earth comes about as follows ...

	* The op' amp' has a very high open loop gain.		* The op' amp' has a very high open loop gain.

Bistable Latch

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	* Left: Two NAND Gates.		* Left: Two NAND Gates.
	* Middle: {{OL}}Set{{LO}} and {{OL}}Reset{{LO}} are shown as little circles.		* Middle: {{OL}}Set{{LO}} and {{OL}}Reset{{LO}} are shown as little circles.
-	* Right: {{OL}}Set{{LO}} and {{OL}}Reset{{LO}} are ~~labeled~~.	+	* Right: {{OL}}Set{{LO}} and {{OL}}Reset{{LO}} are labelled.

	[[File:NAND-Bistable.gif]]{{Tab}}[[File:NAND-Bistable-2.gif]]		[[File:NAND-Bistable.gif]]{{Tab}}[[File:NAND-Bistable-2.gif]]

EMF and Potential Difference

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	* Calculate the resistance of each resistor using Ohm's law:{{Tab}}R = V / I		* Calculate the resistance of each resistor using Ohm's law:{{Tab}}R = V / I
-	* Do your answers match the ~~labeled~~ resistor values?	+	* Do your answers match the labelled resistor values?
	* If not, why not?		* If not, why not?
	* How accurately are the resistors manufactured?		* How accurately are the resistors manufactured?

ReviseOmatic

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	* There are a couple of exceptions to this rule.		* There are a couple of exceptions to this rule.
	* JMP (jump) commands make the program counter point to a completely new address.		* JMP (jump) commands make the program counter point to a completely new address.
-	* JMP START causes the program to jump to the Destination Address ~~labeled~~ by START:	+	* JMP START causes the program to jump to the Destination Address labelled by START:

	'''TASK:'''		'''TASK:'''
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	[[File:Assembler-5.gif]]		[[File:Assembler-5.gif]]

-	* CALL alters PC to the address ~~labeled~~ by DELAY:	+	* CALL alters PC to the address labelled by DELAY:
	* CALL also saves a "return address" on the Stack and SP is altered.		* CALL also saves a "return address" on the Stack and SP is altered.
	* SP is the stack pointer register. SP points to the next free stack location.		* SP is the stack pointer register. SP points to the next free stack location.

Flow Chart Symbols

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	* boxes to represent '''processes''' (do something)		* boxes to represent '''processes''' (do something)
	* diamonds to represent '''questions''', usually with a yes/no answer		* diamonds to represent '''questions''', usually with a yes/no answer
-	* small ~~labeled~~ circles to '''join the pages''' of multi-page flow charts	+	* small labelled circles to '''join the pages''' of multi-page flow charts
	* '''slanty boxes''' for inputs and outputs		* '''slanty boxes''' for inputs and outputs

-	Flow charts are usually read left to right and top down, like normal Roman text. Flow lines should be ~~labeled~~ with arrows. This is especially important if the arrow is going up or right to left.	+	Flow charts are usually read left to right and top down, like normal Roman text. Flow lines should be labelled with arrows. This is especially important if the arrow is going up or right to left.

	== The Symbols ==		== The Symbols ==

Ultrasound Project

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	This collection of pages includes designs for transmitters and receivers but the carrier will be a 40kHz ultrasound wave instead of a radio wave.		This collection of pages includes designs for transmitters and receivers but the carrier will be a 40kHz ultrasound wave instead of a radio wave.

-	* The transmit device is ~~labeled~~ with a T.	+	* The transmit device is labelled with a T.
-	* The receive device is ~~labeled~~ with an R.	+	* The receive device is labelled with an R.

	[[File:Ultrasound-T-R.jpg]] JPR Electronics part number [http://www.jprelec.co.uk/store.asp/c=282/highsku=594-058#594-058 594-058].		[[File:Ultrasound-T-R.jpg]] JPR Electronics part number [http://www.jprelec.co.uk/store.asp/c=282/highsku=594-058#594-058 594-058].

Assembler Documentation

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	Increment the contents of R<br />		Increment the contents of R<br />
	Increment register 0x35<br />		Increment register 0x35<br />
-	Increment register ~~labeled~~ by COUNTER:	+	Increment register labelled by COUNTER:
	\|		\|
	(R) <= (R) + 1		(R) <= (R) + 1
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	Decrement the contents of R<br />		Decrement the contents of R<br />
	Decrement register 0xCF<br />		Decrement register 0xCF<br />
-	Decrement register ~~labeled~~ by TOTAL:	+	Decrement register labelled by TOTAL:
	\|		\|
	(R) <= (R) - 1		(R) <= (R) - 1
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	Jump to K (GOTO)<br />		Jump to K (GOTO)<br />
	Jump to address 0<br />		Jump to address 0<br />
-	Jump to the address ~~labeled~~ with START:	+	Jump to the address labelled with START:
	\|		\|
	PC <= K		PC <= K
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	Jump to K if the Zero Flag is set<br />		Jump to K if the Zero Flag is set<br />
	Jump to address 0x55 if the Zero Flag is set<br />		Jump to address 0x55 if the Zero Flag is set<br />
-	Jump to address ~~labeled~~ by FINISHED: if the Zero Flag is set	+	Jump to address labelled by FINISHED: if the Zero Flag is set
	\|		\|
	PC <= K		PC <= K
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	Jump to K if the Carry Flag is set<br />		Jump to K if the Carry Flag is set<br />
	Jump to address 0x3C if the Carry Flag is set<br />		Jump to address 0x3C if the Carry Flag is set<br />
-	Jump to address ~~labeled~~ by OVERFLOW: if the Carry Flag is set	+	Jump to address labelled by OVERFLOW: if the Carry Flag is set
	\|		\|
	PC <= K		PC <= K
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	Copy from W into the register with address 0x50<br />		Copy from W into the register with address 0x50<br />
	Copy from W into the register with the address		Copy from W into the register with the address
-	~~labeled~~ by MY_VAR:	+	labelled by MY_VAR:
	\|		\|
	(R) <= W		(R) <= W
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	Copy the contents of R to W<br />		Copy the contents of R to W<br />
	Copy the contents of register 0x50 to W<br />		Copy the contents of register 0x50 to W<br />
-	Copy the contents of the register ~~labeled~~ by MY_VAR into W	+	Copy the contents of the register labelled by MY_VAR into W
	\|		\|
	W <= (R)		W <= (R)
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	The AQA "Changes to Content" document describes the use of literals as both labels and values. But it does not have a way to define them in a program. Many assembler languages use DB for this purpose so it has been added as an extra to the AQA instruction set. In high level languages, these named memory locations are called variables.		The AQA "Changes to Content" document describes the use of literals as both labels and values. But it does not have a way to define them in a program. Many assembler languages use DB for this purpose so it has been added as an extra to the AQA instruction set. In high level languages, these named memory locations are called variables.

-	Using DB, it is possible to name a memory location and refer to the contents of the location by name. In addition, data can be stored using DB, even if the memory location is not ~~labeled~~ but this is poor programing style as the program is less easy to understand.	+	Using DB, it is possible to name a memory location and refer to the contents of the location by name. In addition, data can be stored using DB, even if the memory location is not labelled but this is poor programing style as the program is less easy to understand.

	Run this example and watch how the named memory locations get initialised when the program is assembled and how they change when it's run.		Run this example and watch how the named memory locations get initialised when the program is assembled and how they change when it's run.

Subroutines

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	\|- valign="top"		\|- valign="top"
	\|CALL DELAY		\|CALL DELAY
-	\|{{Tab}}This copies 7 (the address ~~labeled~~ by DELAY) into the program counter.	+	\|{{Tab}}This copies 7 (the address labelled by DELAY) into the program counter.

	{{Tab}}This also copies 4 (the return address) onto the stack.		{{Tab}}This also copies 4 (the return address) onto the stack.
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	\|- valign="top"		\|- valign="top"
	\|JMP START		\|JMP START
-	\|{{Tab}}This copies 0 (the address ~~labeled~~ by START) into the program counter.	+	\|{{Tab}}This copies 0 (the address labelled by START) into the program counter.
	\|}		\|}

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	\|- valign="top"		\|- valign="top"
	\|CALL DELAY		\|CALL DELAY
-	\|{{Tab}}This copies 7 (the address ~~labeled~~ by DELAY) into the program counter.	+	\|{{Tab}}This copies 7 (the address labelled by DELAY) into the program counter.

	{{Tab}}This also copies 4 (the return address) onto the stack.		{{Tab}}This also copies 4 (the return address) onto the stack.
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	\|- valign="top"		\|- valign="top"
	\|JMP REP		\|JMP REP
-	\|{{Tab}}This will set the program counter to the address ~~labeled~~ by REP (address eight).	+	\|{{Tab}}This will set the program counter to the address labelled by REP (address eight).
	\|- valign="top"		\|- valign="top"
	\|DONE:		\|DONE:
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	\|- valign="top"		\|- valign="top"
	\|JMP START		\|JMP START
-	\|{{Tab}}This copies 0 (the address ~~labeled~~ by START) into the program counter.	+	\|{{Tab}}This copies 0 (the address labelled by START) into the program counter.
	\|}		\|}

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	\|- valign="top"		\|- valign="top"
	\|CALL DELAY		\|CALL DELAY
-	\|{{Tab}}This copies 7 (the address ~~labeled~~ by DELAY) into the program counter.	+	\|{{Tab}}This copies 7 (the address labelled by DELAY) into the program counter.

	{{Tab}}This also copies 4 (the return address) onto the stack.		{{Tab}}This also copies 4 (the return address) onto the stack.
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	\|- valign="top"		\|- valign="top"
	\|JMP DELAY		\|JMP DELAY
-	\|{{Tab}}This will set the program counter to the address ~~labeled~~ by REP (address eight).	+	\|{{Tab}}This will set the program counter to the address labelled by REP (address eight).
	\|- valign="top"		\|- valign="top"
	\|DONE:		\|DONE:
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	\|- valign="top"		\|- valign="top"
	\|JMP START		\|JMP START
-	\|{{Tab}}This copies 0 (the address ~~labeled~~ by START) into the program counter.	+	\|{{Tab}}This copies 0 (the address labelled by START) into the program counter.
	\|}		\|}

Capacitors

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	* In logic gate astable circuits because the polarity across the capacitor reverses		* In logic gate astable circuits because the polarity across the capacitor reverses

-	== Capacitor ~~Labeling~~ ==	+	== Capacitor Labelling ==

	{\| border="1" cellspacing="0" cellpadding="4"		{\| border="1" cellspacing="0" cellpadding="4"
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	\| '''Big Capacitors''' \|\| These have the value printed in plain language like 4700 µF and there is no problem.		\| '''Big Capacitors''' \|\| These have the value printed in plain language like 4700 µF and there is no problem.
	\|-		\|-
-	\| '''Tiny Capacitors''' \|\| Tiny capacitors might be ~~labeled~~ with a number up to three digits long. These are values in picofarads (puffs) and the third digit (if present) is the number of zeros you need to add. If there is a letter, this is the capacitor tolerance (accuracy of manufacture). J = 5%. K = 10%. M = 20%. Google for the other tolerance codes if you need them.	+	\| '''Tiny Capacitors''' \|\| Tiny capacitors might be labelled with a number up to three digits long. These are values in picofarads (puffs) and the third digit (if present) is the number of zeros you need to add. If there is a letter, this is the capacitor tolerance (accuracy of manufacture). J = 5%. K = 10%. M = 20%. Google for the other tolerance codes if you need them.

	Examples:		Examples:
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	* 473 = 47000 picofarads or 47 nanofarads (add three zeros)		* 473 = 47000 picofarads or 47 nanofarads (add three zeros)
	\|-		\|-
-	\| '''Working Voltage''' \|\| On big capacitors, this is clearly ~~labeled~~. On tiny capacitors it might not be ~~labeled~~ at all. Usually small capacitors will be safe in any AQA project circuit because they have a high enough voltage rating. Electrolytic capacitors are more of a problem. You must take care that the voltage rating is higher than any voltage the capacitor will experience at any time in your circuit. It is a good idea to allow a safety margin so use a 16 Volt capacitor in a 12 Volt circuit. High voltage capacitors tend to be physically large so, if possible, it is a good idea to design circuits to work on lower voltages. Alternatively design circuits that avoid the use of capacitors.	+	\| '''Working Voltage''' \|\| On big capacitors, this is clearly labelled. On tiny capacitors it might not be labelled at all. Usually small capacitors will be safe in any AQA project circuit because they have a high enough voltage rating. Electrolytic capacitors are more of a problem. You must take care that the voltage rating is higher than any voltage the capacitor will experience at any time in your circuit. It is a good idea to allow a safety margin so use a 16 Volt capacitor in a 12 Volt circuit. High voltage capacitors tend to be physically large so, if possible, it is a good idea to design circuits to work on lower voltages. Alternatively design circuits that avoid the use of capacitors.
	\|}		\|}

Heat Sinks

2012-05-15T15:08:47Z

Heat Sink Ratings:

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	\|}		\|}

-	== Heat Sink Ratings ==	+	== Heat Sink Ratings or Thermal Resistance ==

-	The heatsink ~~rating~~ number tells you how much the heatsink temperature will rise when one watt of heat is dissipated. Bigger heatsinks get rid of waste heat more easily so their temperature rises less.	+	The heatsink thermal resistance number tells you how much the heatsink temperature will rise when one watt of heat is dissipated. Bigger heatsinks get rid of waste heat more easily so their temperature rises less so lower numbers indicate more effective heatsinks.

-	* Heatsinks are rated in Degrees per Watt	+	* Heatsinks are rated in Degrees per Watt.<br />
-	* Temperature_Rise = Power_Dissipated x ~~Heatsink_Rating~~	+	* Rearranging the Formulas ...<br />
		+	** Temperature_Rise = Power_Dissipated x Thermal_Resistance<br />
		+	** Power_Dissipated = Temperature_Rise / Thermal_Resistance<br />
		+	** Thermal_Resistance = Temperature_Rise / Power_Dissipated<br />

	Power_Dissipated = Volts x Amps		Power_Dissipated = Volts x Amps

Electronics Home

2012-05-14T12:04:41Z

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	[[Yacapaca]]<br />		[[Yacapaca]]<br />
	[http://softwareforeducation.com/wikilekiextra/Revision_AS/index.php AS Revision]<br />		[http://softwareforeducation.com/wikilekiextra/Revision_AS/index.php AS Revision]<br />
-	A2 Revision	+	[http://softwareforeducation.com/wikilekiextra/Revision_A2/index.php A2 Revision]
	\|		\|
	''' More Resources '''		''' More Resources '''

Antenna

2012-05-11T13:19:00Z

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-	{{NAV\|topic={{A2}}\|nav={{RX}}}}	+	{{NAV\|topic={{GCSE}}{{A2}}\|nav={{RX}}}}

	== Antenna Basics ==		== Antenna Basics ==
-		+	{{GCSE}}{{A2}}
-	An antenna is a transducer designed to transmit or receive electromagnetic energy (radio waves) to or from the medium of free space. Antennas are designed to do this as efficiently as possible.	+	* A receiving antenna converts electromagnetic radiation (radio waves) into an alternating current or voltage.
		+	* A transmitting antenna converts an alternating current or voltage into electromagnetic radiation (radio waves).
		+	* An antenna is a transducer designed to transmit or receive electromagnetic energy (radio waves) to or from the medium of free space.
		+	* Antennas are designed to do this as efficiently as possible.
		+	* A good transmitting antenna will also be a good receiving antenna.

	== Half Wave Dipole Antenna ==		== Half Wave Dipole Antenna ==
-		+	{{A2}}
	[[File:Antenna-dipole.gif]]		[[File:Antenna-dipole.gif]]

	* The dipole is a very common antenna and it is '''half a wavelength long'''.		* The dipole is a very common antenna and it is '''half a wavelength long'''.
-	* A good transmitting antenna will also be a good receiving antenna.
	* This antenna works best when the waves arrive broadside. End-on the antenna is very inefficient.		* This antenna works best when the waves arrive broadside. End-on the antenna is very inefficient.

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	\|}		\|}

-	This gives a feel for what happens in an antenna. ~~The~~ electron movement is greatly exaggerated. In real life, each electron moves fractions of a millimetre but there are huge numbers of electrons moving.	+	This gives a feel for what happens in an antenna. In the animation, the electron movement is greatly exaggerated. In real life, each electron moves fractions of a millimetre but there are huge numbers of electrons moving.

	== Antenna Calculations ==		== Antenna Calculations ==
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	Light can also be polarised. Light reflected off water or road surfaces is partially polarised. Polaroid sun glasses selectively filter out the reflected polarised light waves. This reduces the glare effect of the reflected light.		Light can also be polarised. Light reflected off water or road surfaces is partially polarised. Polaroid sun glasses selectively filter out the reflected polarised light waves. This reduces the glare effect of the reflected light.
-
-	~~== Yagi Antenna ==~~
-
-	~~[[File:Antenna-Yagi.jpg \| left]]~~
-
-	These are based on the half wave dipole but the other elements make the antenna directional. In the forward direction, they work much better than a dipole. In other directions they are much less efficient than a dipole. The connection of the co-axial cable is usually more complex than shown to maximise the transfer of energy from the antenna to the feeder cable.
-
-	~~[[File:Antenna-Yagi.gif]]~~
-
-	On the left, is a vertically polarised Yagi antenna used for remote power line switching. This antenna is quite directional. It works better in the wanted direction as well as rejecting signals from the wrong direction.<br clear="all" />
-
-	~~== Quarter Wave Vertical Antenna ==~~
-
-	This antenna is a quarter of a wavelength long and is usually vertical. The earth acts as a mirror and there is a mirror image quarter wave underground. The antenna and the mirror image behave very like a half wave dipole. Telescopic radio aerials work on this principle. For example a car's aerial will be about a quarter wave long and the car body acts as the earth to provide the mirror image. For the 100 MHz FM radio band, the antenna will be about 75 cm long.

	== Impedance Matching ==		== Impedance Matching ==
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	[[File:Douai-70-04.jpg]]		[[File:Douai-70-04.jpg]]
		+
		+	== Yagi Antenna ==
		+	{{Ex}}
		+	[[File:Antenna-Yagi.jpg \| left]]
		+
		+	These are based on the half wave dipole but the other elements make the antenna directional. In the forward direction, they work much better than a dipole. In other directions they are much less efficient than a dipole. The connection of the co-axial cable is usually more complex than shown to maximise the transfer of energy from the antenna to the feeder cable.
		+
		+	[[File:Antenna-Yagi.gif]]
		+
		+	On the left, is a vertically polarised Yagi antenna used for remote power line switching. This antenna is quite directional. It works better in the wanted direction as well as rejecting signals from the wrong direction.<br clear="all" />
		+
		+	== Quarter Wave Vertical Antenna ==
		+
		+	This antenna is a quarter of a wavelength long and is usually vertical. The earth acts as a mirror and there is a mirror image quarter wave underground. The antenna and the mirror image behave very like a half wave dipole. Telescopic radio aerials work on this principle. For example a car's aerial will be about a quarter wave long and the car body acts as the earth to provide the mirror image. For the 100 MHz FM radio band, the antenna will be about 75 cm long.

	[[Category:Antenna]]		[[Category:Antenna]]
	[[Category:Polarisation]]		[[Category:Polarisation]]
	[[Category:Transducers]]		[[Category:Transducers]]

Superhet Receiver

2012-05-11T13:06:45Z

The Supersonic Heterodyne Receiver:

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	* This problem can be minimised with a simple filter between the antenna and receiver.		* This problem can be minimised with a simple filter between the antenna and receiver.
	* At the antenna a band pass filter can be used to reject all frequencies outside the desired band.		* At the antenna a band pass filter can be used to reject all frequencies outside the desired band.
		+	* The local oscillator needs to produce a pure sine wave on a single frequency. This is hard to achieve. If the oscillator signal is distorted, there will be harmonics (multiples of the wanted frequency). The mixer can mix these harmonics with unwanted signals from the antenna and the correct IF is produced. These are called spurious responses. Top quality receivers which minimise such problems are costly! Distortion in the mixer causes similar problems.

	== Superhet Subsystems ==		== Superhet Subsystems ==

Simple Receiver

2012-05-11T12:58:32Z

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	[[File:Radio-Simple.GIF]]		[[File:Radio-Simple.GIF]]

-	* The receiving antenna converts radio waves (electromagnetic radiation) into a radio frequency alternating current.	+	* The receiving antenna converts radio waves (electromagnetic radiation) into a radio frequency alternating voltage or current.
		+	* The tuned circuit selects the wanted frequency (radio station) and rejects other frequencies.
	* The demodulator separates the information signal (music, speech, remote control data) from the modulated radio signal.		* The demodulator separates the information signal (music, speech, remote control data) from the modulated radio signal.
	* The low pass filter passes the information signal and blocks the radio frequencies.		* The low pass filter passes the information signal and blocks the radio frequencies.
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	'''Some terminology ...'''		'''Some terminology ...'''

		+	* Modulation: The radio frequency carrier signal is modified by the information signal.
		+	* AM: Amplitude modulation. The amplitude (size) of the radio frequency carrier signal is modified in step with the information signal.
		+	* FM: Frequency modulation. The frequency of the radio frequency carrier signal is modified in step with the information signal.
	* Sensitivity: The ability to receive weak signals.		* Sensitivity: The ability to receive weak signals.
	* Selectivity: The ability to tune in one station and reject others on close frequencies.		* Selectivity: The ability to tune in one station and reject others on close frequencies.

Op Amp Summary

2012-05-11T10:57:41Z

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	== Op Amp Revision Key facts ==		== Op Amp Revision Key facts ==

-	[[~~File~~:OpAmpSummary.pdf\|Summary PDF]]	+	[[Media:OpAmpSummary.pdf\|Summary PDF]]

	{\| border="1" cellspacing="0" cellpadding="4"		{\| border="1" cellspacing="0" cellpadding="4"

File:OpAmpSummary.pdf

2012-05-11T10:56:42Z

deleted "[[File:OpAmpSummary.pdf]]" Deleted old revision 20120511105628!OpAmpSummary.pdf

Op Amp Summary

2012-05-11T10:56:02Z

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	== Op Amp Revision Key facts ==		== Op Amp Revision Key facts ==

-	[[~~Media~~:OpAmpSummary.pdf\|Summary PDF]]	+	[[File:OpAmpSummary.pdf\|Summary PDF]]

	{\| border="1" cellspacing="0" cellpadding="4"		{\| border="1" cellspacing="0" cellpadding="4"

13 555 Timer Test

2012-05-11T08:28:16Z

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	# Draw the circuit diagram for a Monostable circuit.<br />[[File:555-Blank.gif]]{{NQ}}		# Draw the circuit diagram for a Monostable circuit.<br />[[File:555-Blank.gif]]{{NQ}}
		+	# Explain how this circuit works.{{NQ}}
	# Add an LED to the diagram above. The LED should be on during the timing period.{{NQ}}		# Add an LED to the diagram above. The LED should be on during the timing period.{{NQ}}
	# Add a buzzer to the diagram above. The buzzer should sound when the timing period is completed.{{NQ}}		# Add a buzzer to the diagram above. The buzzer should sound when the timing period is completed.{{NQ}}
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	# If a 2 megohm resistor is used, calculate the capacitor needed to time 4.84 seconds.{{NQ}}		# If a 2 megohm resistor is used, calculate the capacitor needed to time 4.84 seconds.{{NQ}}
	# Draw the circuit diagram for an Astable circuit.<br />[[File:555-Blank.gif]]{{NQ}}		# Draw the circuit diagram for an Astable circuit.<br />[[File:555-Blank.gif]]{{NQ}}
		+	# Explain how the astable works.{{NQ}}
	# Calculate the period of the astable if Ra is 10 kilohms, Rb is 100 kilohms and C is 100 nanofarads.{{NQ}}		# Calculate the period of the astable if Ra is 10 kilohms, Rb is 100 kilohms and C is 100 nanofarads.{{NQ}}

	[[Category:Ten Mark Test]]		[[Category:Ten Mark Test]]

Careers

2012-05-11T08:11:47Z

Major Electrical and Electronics Businesses:

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	\|- valign="top"		\|- valign="top"
	\|		\|
-	* [http://www.alstom.com/careers/ Alstom]
	* [http://www.airbus.com/work/ Airbus]		* [http://www.airbus.com/work/ Airbus]
		+	* [http://www.alstom.com/careers/ Alstom]
		+	* [http://www.astrium.eads.net/ Astrium]
	* [http://www.baesystems.com/Careers/ BAE Systems]		* [http://www.baesystems.com/Careers/ BAE Systems]
	* [http://www.bbc.co.uk/careers/home BBC]		* [http://www.bbc.co.uk/careers/home BBC]

File:13 555 Timer Test.pdf

2012-05-11T08:00:13Z

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-	[[Category:Ten ~~mark~~ Test]]	+	[[Category:Ten Mark Test]]

File:13 555 Timer Test.pdf

2012-05-11T07:59:59Z

uploaded "[[File:13 555 Timer Test.pdf]]" Category:Ten mark Test

13 555 Timer Test

2012-05-11T07:56:37Z

Created page with "== {{GCSE}}{{AS}} Your Name: == PDF Version # Draw the circuit diagram for a Monostable circuit.<br />File:555-Blank.gif{{NQ}} # Add an LED ..."

New page

== {{GCSE}}{{AS}} Your Name: ==

[[Media:13_555_Timer_Test.pdf|PDF Version]]

# Draw the circuit diagram for a Monostable circuit.<br />[[File:555-Blank.gif]]{{NQ}}
# Add an LED to the diagram above. The LED should be on during the timing period.{{NQ}}
# Add a buzzer to the diagram above. The buzzer should sound when the timing period is completed.{{NQ}}
# Write down the formula for the Monostable period.{{NQ}}
# If a 10 microfarad timing capacitor is used, calculate the resistor needed to time 5.17 seconds.{{NQ}}
# If a 2 megohm resistor is used, calculate the capacitor needed to time 4.84 seconds.{{NQ}}
# Draw the circuit diagram for an Astable circuit.<br />[[File:555-Blank.gif]]{{NQ}}
# Calculate the period of the astable if Ra is 10 kilohms, Rb is 100 kilohms and C is 100 nanofarads.{{NQ}}

[[Category:Ten Mark Test]]

File:555-Blank.gif

2012-05-11T07:48:05Z

uploaded "[[File:555-Blank.gif]]" Category:Ten Mark Test

MOSFET Push Pull Amplifier

2012-05-10T11:49:11Z

RMS Output Power:

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	Power = 24.5 Watts		Power = 24.5 Watts
		+
		+	This is the theoretical maximum power output.
		+
		+	=== Real Life Power Output ===
		+
		+	In real life, MOSFET push pull source followers are not perfect. The output will be lower than expected because ...
		+
		+	# The driver op-amp saturates a couple of volts below the power supply voltage.
		+	# 2 or 3 volts are lost across the gate source junction in the MOSFETs.
		+	# 0.7 to 4 Volts get lost in the biasing diodes depending on the type of diode used.
		+	# The MOSFETs have Drain to Source resistance. Energy is lost here.
		+
		+	Points 1 to 3 above can be fixed by running the op-amp driver and MOSFET biasing on a higher power supply voltage. As these are low power circuits, this is not too expensive to do.

	== Falstad Simulations ==		== Falstad Simulations ==

CTCSS

2012-05-10T10:09:14Z

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	== Continuous Tone Coded Squelch System ==		== Continuous Tone Coded Squelch System ==

-	* Some VHF ~~receivers~~ use CTCSS.	+	* Some VHF transceivers use CTCSS.
	* This is a continuous tone below 300 Hz.		* This is a continuous tone below 300 Hz.
	* The receiver is only activated if the correct CTCSS tone is present.		* The receiver is only activated if the correct CTCSS tone is present.

Template:NAVMOD

2012-05-10T10:06:45Z

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-	[[AM]] - [[AM Transmitter\|TX]]{{Ta4}}[[FM]] - [[VHF FM Transmitter\|TX]]{{Ta4}}[[AM FM Comparison]]{{Ta4}}[[Digital Modulation]] - [[DAB]] - [[Advanced Digital Radio]]{{Ta4}}[[RTFQ1]] - [[FM-RRFQ1~~]] - [[CTCSS~~]]	+	[[AM]] - [[AM Transmitter\|TX]]{{Ta4}}[[FM]] - [[CTCSS]] - [[VHF FM Transmitter\|TX]]{{Ta4}}[[AM FM Comparison]]{{Ta4}}[[Digital Modulation]] - [[DAB]] - [[Advanced Digital Radio]]{{Ta4}}[[RTFQ1]] - [[FM-RRFQ1]]

Category:CTCSS

2012-05-10T10:05:26Z

Created page with "Category:Definitions"

New page

[[Category:Definitions]]

CTCSS

2012-05-10T10:05:05Z

Created page with "{{NAV|topic={{A2}}|nav={{NAVMOD}}}} == Continuous Tone Coded Squelch System == * Some VHF receivers use CTCSS. * This is a continuous tone below 300 Hz. * The receiver is only ..."

New page

{{NAV|topic={{A2}}|nav={{NAVMOD}}}}

== Continuous Tone Coded Squelch System ==

* Some VHF receivers use CTCSS.
* This is a continuous tone below 300 Hz.
* The receiver is only activated if the correct CTCSS tone is present.
* This allows different organisations to share the same frequency without having to listen to each others' transmissions.
* This technique allows better use to be made of the limited number of channels available.
* The CTCSS tone is filtered out by the receiver and not passed to the loudspeaker.
* The range of frequencies needed for voice communication is 300 to 3000 Hz.
* Filtering out frequencies below 300 Hz has little effect on the audio quality.

[[Category:CTCSS]]

Template:NAVMOD

2012-05-10T09:57:06Z

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-	[[AM]] - [[AM Transmitter\|TX]]{{Ta4}}[[FM]] - [[VHF FM Transmitter\|TX]]{{Ta4}}[[AM FM Comparison]]{{Ta4}}[[Digital Modulation]] - [[DAB]] - [[Advanced Digital Radio]]{{Ta4}}[[RTFQ1]] - [[FM-RRFQ1]]	+	[[AM]] - [[AM Transmitter\|TX]]{{Ta4}}[[FM]] - [[VHF FM Transmitter\|TX]]{{Ta4}}[[AM FM Comparison]]{{Ta4}}[[Digital Modulation]] - [[DAB]] - [[Advanced Digital Radio]]{{Ta4}}[[RTFQ1]] - [[FM-RRFQ1]] - [[CTCSS]]