LC oscillator component values

[froten]

hello all,

when designing LC oscillators, is there a rule of thump on how to select the L & C values? How I can select these values for a specific frquency?

any help is very appreciated

 

[Nigel Goodwin]

Just use the standard formula for LC resonance - or one of the many on-line calculators.

This is the top answer on google.

 

[froten]

Thanks for the replay.

My quesion is on selecting the values, for example:

440pF & 0.5UH will reasonate at 10.7MHz
220pF & 1UH will reasonate at 10.7MHz
110pF & 2UH will reasonate at 10.7MHz
55pF & 4UH will reasonate at 10.7MHz

so which values are the best?

 

[Nigel Goodwin]

The values affect the Q of the tuned circuit, have a read at:

Tuned LC circuits

What are you trying to do?.

 

[JimB]

Thanks for the replay.

My quesion is on selecting the values, for example:

440pF & 0.5UH will reasonate at 10.7MHz
220pF & 1UH will reasonate at 10.7MHz
110pF & 2UH will reasonate at 10.7MHz
55pF & 4UH will reasonate at 10.7MHz

so which values are the best?

A reference I have indicates that the reactance of the coil in a Colpitts oscillator should be around 140 ohms, so for 10.7Mhz, this calculates out as a 2uH coil.

JimB