what type of oscillator!?

Question

here is a image of a oscillator! " http://www.flickr.com/photos/aj_silverthunder/4157840441/ ".
my doubt is which type of oscillator is this.
what is the frequency of the oscillator!
is the frequency of the oscillator is stable!
does it have frequency drift!
should i add all the values of the capacitors(BB139,15pF,33pF,22pF) and the value of the L1 is 100nH then what could be the frequency of the oscillator!

Answer 1

The circuit is a fairly basic

configuration of a COLPITTS Oscillator.



The capacitive divider, 33pf and 22pf are the key

to identifying it as such plus the parallel tuning. If

it was series tuned it would be a Clapp Oscillator.

AC analysis: Top of 33pf to Base, Junction to Emitter,

and lower end of the 22pf to Collector, via 100nf

and 100 ohm.



The frequency operates in Band 2, the FM radio band.

Effective tuning capacitance consists of Cvaricaps

paralleled with; series 15pf, (33pf,paralleled with C b-e)

and 22pf; paralleled with C stray.

C varicaps mid range approx 11.4 pf

C b-e 20pf

C stray 6 pf



Working this out gives a total tuning capacitance

of 25pf

25pf and 100nf resonate at 100.6 Mhz



Use 10k to tune frequency +/- 10Mhz



Frequency stability will mostly be decided by the

thermal characteristics of the components used

in the frequency determining section of the circuit.

Answer 2

The resonant frequency of the tank circuit, consists of L1, the two varicap diodes in series, and the 15 pf in series with the input capacitance of the transistor.



But this oscillator, if it is one, is not similar to any of the traditional oscillators, so it's a mystery to me.



.

Answer 3

basically none are very stable. In a stable oscillator the soundness is often based on the aspects use to set the frequency, so any Rs Cs and Ls must be examined for stability and temperature waft. At that frequency that includes capacitance of wires and enter and output capacitances of any transistors. .

Answer 4

It is modified Clapp oscillator.

Using given values , theoretical frequency comes out to about 150MHz. It is possible that actuall will be lower given parasitic capacitance of elements, possibly in 100-108 Mhz range