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rf oscillator circuit
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Topic: rf oscillator circuit (Read 1873 times)
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yalect
Regular Contributor
Posts: 123
rf oscillator circuit
«
on:
September 17, 2018, 08:45:23 am »
Hello,
I would like to ask you how this oscillator works? and crystal has to shift phase 180 degree to pevent negative feedback?
thank you
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paul@yahrprobert.com
Regular Contributor
Posts: 79
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Re: rf oscillator circuit
«
Reply #1 on:
September 18, 2018, 04:02:47 am »
No, the crystal run in series resonance mode. That is, at a particular frequency it has a purely resistive impedance. The transistor provides the 180 degree phase shift, that is the collector voltage drops when the base current rises.
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yalect
Regular Contributor
Posts: 123
Re: rf oscillator circuit
«
Reply #2 on:
September 18, 2018, 08:31:31 am »
Hi,
thank you
but how that oscillator works where must it has positive feedback and phase shift, maybe quertz has phase shift and what is it?
thanks
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iMo
Super Contributor
Posts: 4782
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It's important to try new things..
Re: rf oscillator circuit
«
Reply #3 on:
September 19, 2018, 10:08:21 am »
It is the Pierce oscillator. The crystal and parasitic capacitances create the 180deg phase shift. Near its resonance freq the crystal in that circuit is equivalent to a C-L-C (pi network) resonant tank.
«
Last Edit: September 19, 2018, 10:10:16 am by imo
»
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yalect
Regular Contributor
Posts: 123
Re: rf oscillator circuit
«
Reply #4 on:
September 22, 2018, 06:24:48 am »
Thank you
phase shift is 180 degree? And Crystal make it ?
Thanks
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lordvader88
Frequent Contributor
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Posts: 935
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Re: rf oscillator circuit
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Reply #5 on:
September 23, 2018, 09:40:21 pm »
Here's what I studied today
I need to try the AC analysis on a metal I'm made today
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rf oscillator circuit
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