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Frequency Generation Without An Oscillator Ckt:multisim Simulation

faltu

May 15, 2017
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hey guys,i was trying to get frequency without using any predefined oscillator ckt and i used an inductor.but now i m confused why i m getting any frequency as inductor acts as short circuit in dc sourceinductor.png
 

duke37

Jan 9, 2011
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To get a tuned oscillator you will need a tank circuit consisting of an inductor and capacitor. Various methods are used to tap into this circuit to provide power from the transistor and another tap is used to drive the transistor.
If the circuit shows an oscillation, it will be using the transistor capacitances to set the frequency.
Look up Hartley, Colpits and Clap.
Your circuit is presumably a simulation, 50A will soon let the smoke out of a BC547.
 

Audioguru

Sep 24, 2016
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50A in a little BC547? Why doesn't Multisim read the maximum allowed ratings on the datasheet? it is 100mA (0.1A).
 

faltu

May 15, 2017
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thanks duke37,
yaa is there any solution to the problem audioguru pointed out
 

duke37

Jan 9, 2011
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Or find out how transistors are biased so that they pass sufficient current to do the job but not enough to damage them.
 

LvW

Apr 12, 2014
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Remember the oscillation condition:
The loop gain (the gain around the complete feedback loop) must be unity - unity magnitude AND zero phase - for ONE SINGLE frequency only!.
 

AnalogKid

Jun 10, 2015
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hey guys,i was trying to get frequency without using any predefined oscillator ckt and i used an inductor.but now i m confused why i m getting any frequency as inductor acts as short circuit in dc sourceView attachment 34028
By definition, a frequency is not DC. The function of any oscillator circuit is to turn DC into AC of some form.

ak
 

faltu

May 15, 2017
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yes , i got the answer i was getting frequency due to the parasitic capacitance both in inductor and bjts as duke indicated
 
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