Oscillator Design - Revision history

TimVK4YEH: fixed spelling error - new page required

2010-11-16T21:44:53Z

fixed spelling error - new page required

← Older revision		Revision as of 14:44, 16 November 2010
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	=== Frequency Production===		=== Frequency Production===

	Oscillator frequency is usually produced using a resonant LC ciruit or a quartz crystal. Quartz crystals are used where frequency stability is important. See [[~~Piezolelectric~~ Effect]] for more information about quartz crystals. If an LC oscillator is used it should have the following characteristics for maximum stability.		Oscillator frequency is usually produced using a resonant LC ciruit or a quartz crystal. Quartz crystals are used where frequency stability is important. See [[Piezoelectric Effect]] for more information about quartz crystals. If an LC oscillator is used it should have the following characteristics for maximum stability.
	* there should be a high C to L Ratio		* there should be a high C to L Ratio
	* a well regulated power supply should be used		* a well regulated power supply should be used

TimVK4YEH: some info, more needed

2009-11-18T05:37:18Z

some info, more needed

← Older revision		Revision as of 22:37, 17 November 2009
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	=== Armstrong ===		=== Armstrong ===

	The Armstrong oscillator is distinguished by the use of a "tickler coil"~~. In~~ the circuit below, L2 is ~~the tickler coil andis~~ inductively coupled to L1, ~~proving~~ some regeneration to the input of the transistor.		The Armstrong oscillator L1 and C1 on the base of the transistor determine the frequency of operation - C1 is variable allow the frequency to ve varied. This oscillator is distinguished by the use of a "tickler coil" L2 in the circuit below. L2 is inductively coupled to L1, providing some positive feedback (regeneration) to the input of the transistor.

			* Rb determines the bias current.
			* The bias current flows from earth through Re into the emmitter, out through Rb to the positive
			* Re provides emmitter current stabilisation and prevents thermal runaway

	[[Image:Armstrong oscillator.jpg\| 400px]]		[[Image:Armstrong oscillator.jpg\| 400px]]


	=== Hartley ===		=== Hartley ===

TimVK4YEH: added some info - could be expanded upon

2009-11-16T21:12:14Z

added some info - could be expanded upon

← Older revision		Revision as of 14:12, 16 November 2009
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	== Fundamentals ==		== Fundamentals ==

			An oscillator is an electronic circuit designed to produce either audio or radio frequency signals. These will generally have sineusoidal wave form, but other wave shapes such as square and sawtooth are possible. In radio equipment oscillators will always have a low output power, and if a radio frequency is produced, the oscillator is acually a basic radio transmitter.

			In oscillators, the following are deliberate design parametes:
			* frequency production
			* amplification
			* positive feedback, also known as regeneration

			These factors are also present in amplifier operation. Hence design is important as amplifiers should not be oscillators!

			=== Frequency Production===

			Oscillator frequency is usually produced using a resonant LC ciruit or a quartz crystal. Quartz crystals are used where frequency stability is important. See [[Piezolelectric Effect]] for more information about quartz crystals. If an LC oscillator is used it should have the following characteristics for maximum stability.
			* there should be a high C to L Ratio
			* a well regulated power supply should be used
			* there should be good isolation between the oscillator and its load
			* components should exhibit little change in value with changing temperature
			* the oscillator itself should be isolated as much as possible from large temperature changes

			===Buffer amplifier===

			A buffer amlifier is used to improve frequency stability by isolating the oscillator from its load. It is required bacause of the low power produced by oscillators. Drawing on this low power shifts the frequency of the oscillator. Buffer amplifers will have high [[impedance]] so that they draw no power from the oscillator.

			===Drift===

			Drift refers to changes in oscillator frequency due mainly to capacitance changes in the circuit as a result of temperature fluctuations. Drift can be controlled by having the tuning [[Capacitors \|capacitance]] large compared to the tuning [[Inductors \|inductance]]

	== Types of Oscillator ==		== Types of Oscillator ==

TimVK4YEH: /* Clapp */

2009-09-06T07:38:57Z

Clapp

← Older revision		Revision as of 00:38, 6 September 2009
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	=== Clapp ===		=== Clapp ===

	[[Image:Clapp_oscillator.jpg ]]		[[Image:Clapp_oscillator.jpg \|500px]]

	=== Colpitts ===		=== Colpitts ===

TimVK4YEH: added Clapp heading and pic

2009-09-06T07:38:32Z

added Clapp heading and pic

← Older revision		Revision as of 00:38, 6 September 2009
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	[[Image:Hartley_oscillator.jpg \|500px]]		[[Image:Hartley_oscillator.jpg \|500px]]

			=== Clapp ===

			[[Image:Clapp_oscillator.jpg ]]

	=== Colpitts ===		=== Colpitts ===

TimVK4YEH: added pic

2009-09-06T07:36:51Z

added pic

← Older revision		Revision as of 00:36, 6 September 2009
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	=== Colpitts ===		=== Colpitts ===

			[[Image:Colpitts_oscillator.jpg\|500px]]
	{{electronics}}		{{electronics}}
	-		-

TimVK4YEH: hartley pic and some info - needs more info

2009-09-06T07:30:13Z

hartley pic and some info - needs more info

← Older revision		Revision as of 00:30, 6 September 2009
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	=== Hartley ===		=== Hartley ===

			The Hartley oscillator has a tickler coil like the Armstrong oscillator but it is part of the "front end' of the circuit. In the diagram below the tickler coil is the lower part of L1.

			[[Image:Hartley_oscillator.jpg \|500px]]

	=== Colpitts ===		=== Colpitts ===

TimVK4YEH: added armstrong osc and some info - needs more info

2009-09-06T07:23:28Z

added armstrong osc and some info - needs more info

← Older revision		Revision as of 00:23, 6 September 2009
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	== Types of Oscillator ==		== Types of Oscillator ==

			=== Armstrong ===

			The Armstrong oscillator is distinguished by the use of a "tickler coil". In the circuit below, L2 is the tickler coil andis inductively coupled to L1, proving some regeneration to the input of the transistor.

			[[Image:Armstrong oscillator.jpg\| 400px]]


	=== Hartley ===		=== Hartley ===

Carlb: /* Colpitts */

2009-04-09T01:26:33Z

Colpitts

← Older revision		Revision as of 18:26, 8 April 2009
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	=== Colpitts ===		=== Colpitts ===


			{{electronics}}
			-

TimVK4YEH at 08:50, 12 March 2008

2008-03-12T08:50:29Z

← Older revision		Revision as of 01:50, 12 March 2008
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	Related wiki pages [[~~Oscillator~~ Design]], [[Power Supply Design]].		Related wiki pages [[Amplifier Design]], [[Power Supply Design]].

	== Fundamentals ==		== Fundamentals ==