Colpitts oscillators difference

Hello,
can somebody explain me difference between attached colpitts oscilator circuit diagrams please?

Both of them are supposed to be colpitts's, but I am confused of this one because it looks pretty different:
http://en.wikipedia.org/wiki/File:NPN_Colpitts_oscillator_collector_coil.png


Many thanks in advance

Hi RETFIE

Both are Colpitts oscillators as both are using two serial capacitors in parallel with the inductance.

The difference is coming from the amplification stage with the bipolar transistor. in the first case, it is a Common Emitter (CE) configuration while in the second case it is a Common Base (CB) configuration.

Both CE and CB are only applicable to the small signal equivalent circuit of the transistor. If you are not familiarized with these terms, please refer to it through the net (there is a lot of usefull information out there).

The use of CE or CB configuration will depend on many design factors, but for low and medium frequencies (up to 100 MHz) they both are acting similarly (if the transistor is correctly chosen).

Regards,