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Analog circuit analysis discussion – Colpitts oscillator
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AnneRanch:

I am looking to discuss circuit details of Colpitts oscillator.
I have found several circuit versions and having a difficult time to model them using Ltspice .
My objective is to fully understand individual components functions.

I am not looking for troubleshooting , design help , tutorials, u-tube or other references  etc.

I would like to engage  in a meaningful discussion with  someone who “been there, done that”  on component level.
For starters
“the circuit configuration should have minimal gain , just to self-start  the oscillation”
If I select 2N2222 as an active device – how to I make sure it has such “minimal gain “ ?

I would appreciate forum members to carefully read my post and reply only when they  have a meaningful contribution to post.
Cheers
ledtester:
Since you mention a specific active device, it would greatly aid the discussion if you posted the particular Colpitts implementaton you are talking about.
MagicSmoker:

--- Quote from: AnneRanch on September 17, 2019, 02:48:45 pm ---I am looking to discuss circuit details of Colpitts oscillator.
I have found several circuit versions and having a difficult time to model them using Ltspice .
--- End quote ---

Try setting the minimum maximum time step for the transient analysis in LTSpice to something on par with the period of oscillation if your oscillator isn't oscillating.


--- Quote from: AnneRanch on September 17, 2019, 02:48:45 pm ---I would appreciate forum members to carefully read my post and reply only when they  have a meaningful contribution to post.
Cheers

--- End quote ---

That's a bit spicy dontchathink?



EDIT - oops, mistakenly wrote "minimum time step" instead of maximum.
Zero999:

--- Quote from: MagicSmoker on September 17, 2019, 03:09:29 pm ---
--- Quote from: AnneRanch on September 17, 2019, 02:48:45 pm ---I am looking to discuss circuit details of Colpitts oscillator.
I have found several circuit versions and having a difficult time to model them using Ltspice .
--- End quote ---

Try setting the minimum time step for the transient analysis in LTSpice to something on par with the period of oscillation if your oscillator isn't oscillating.

--- End quote ---
Skip initial operating point solution or start DC supply voltages at 0V can also help.

--- Quote ---
--- Quote from: AnneRanch on September 17, 2019, 02:48:45 pm ---I would appreciate forum members to carefully read my post and reply only when they  have a meaningful contribution to post.
Cheers

--- End quote ---

That's a bit spicy dontchathink?

--- End quote ---
They've probably been trolled in the past. Just ignore posts which don't meaningfully contribute to the discussion or report them to the moderator, if they're that bad.
AnneRanch:
Whops
I did reply then it asked me to log in AFTERWARS.
Not sure why.
So hopefully here is the current LTspice file.
The model is NOT tuned properly.
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