Edwin H Colpitts Patent

[pwdrive]

Interesting, I wonder if this gave Clapp an idea, maybe, maybe not, what do you think?

http://patentimages.storage.googleapis.c...4537-0.png

Lawrence.

[boiss]

The only difference if I remember correctly is that the capacitor ratios are different. That said generally the Clapp config is used and called Colpitts.
Mike

[pwdrive]

In general terms the Clapp has a capacitor in series with the inductor, Colpitts original patent has a capacitor in series with the coil in one of his diagrams but he calls it a DC blocking capacitor, weather that could be defined as a Clapp is up for debate.

Lawrence.

[boiss]

Who came first Clapp or Colpitts? The other difference lies in the way feedback is obtained, one has Positive C coupled the other relies on the phase diff between the 2 ends of the L at resonance, Most used examples are Colpitts:- Cathode to grid, Clapp anode to grid.
An aside to this would be the Quartz Clapp relying on Internal C (anode to grid)
Most so called Colpitts have the 3 caps One relatively large value which isolates the Grid/Gate/Base of the non linear device from DC and the other 2 form the feedback/feedforward network. The Dipper cct, (Hartley) has a tapped coil with the tap going to ground one end connected to the Drain and the other to the gate, phase reversal coutesy of the tapped coil. The Variable cap (s) could be connected in parallel across the coil, but this would have upset the stability ( Hand capacitance)With the frame of the cap being live. The variable cap is not a feedback component in se, just a tuning device. At a first glance it appears as a Colpitts which is why it was referred to as such by others I reckon.
Mike
Btw just looking through an old radio book, Have you ever come across metal rectifiers being used as detectors?