SPICE VS real life..

WTF is that? Jamie

Lots of reasons:

(1) Real-life components have tolerances & parasitics (2) Real-life has stray couplings (3) Spice models, particularly for discrete's, are often SWAG's (4) LTspice takes simulation liberties for speed ...Jim Thompson

What are you using to measure the frequencies and where are they connected in your circuit? Also, what is the probe/input impedance (r and C)?

In addition, I question your ability to measure the inductor and resonating capacitors to the precision and accuracy your simulation implies. Do you have any stay capacitance or inductance in the circuit? Your measurements indicate you are only about 11.5% above the LTSpice output.

Waveforms are uglier than I have seen from most Colpitts oscillators. Maybe you are driving too hard.

The 'Colpitts L' (Hartley) oscillator is tapped pretty near top of the tank circuit. The classical rule of thumb is 1/3 from bottom.

The same applies to the capacitively divided circuit. There, C4 is redundant.

Does the practical circuit have good by-pass over the power feed. The simulator assumes zero impedance for the feed supply.

I tried the first one, and got 15.9, so....

upon examination of your inductor 11T 118T and perfect k=1, NO WAY!

something's wrong in your inductor models. N1^2/N2^2 * L2 does NOT equal L!

plus, I found the circuit's performance very sensitive to that inductor's value.

You need to concentrae on modeling your inductor more accurately. The simulation is accurate for the model in there, but your verbal description doesn't match the model in the schematic.

I dunno what that randumb junk is above; certainly NOT the ASCII files i posted.

But...but...motorbut...i measured those values.

My bypass cap is 4.7uF, fairly decent. Yah, i know about the tapped L...too lazy to wind hundreds of turns.

L2 inductance never measured, 11T is accurate; L1 number of turns is estimated, inductance measured. L1 is actually a degaussing coil from a monitor re-shaped into a flattish circle (more or less). Since L2 is wound "on top" of L1,and the diameter is rater large (13.5 inches), K=1 is a reasonable estimate.

That is Base64 encoding. Come on, you've been on Usenet long enough to know these things...

Well, apparently "MicroPlanet-Gravity/3.0.4" doesn't decode it worth a damn. But attaching ASCII files as "application/pgp-signature" seems very disingenuous, however Mozilla/5.0 handles that...

Tim

For a proper Hartley oscillator, you need magnetic coupling between the coils, that is a tapped coil.

You are supporting my argument about the 'model' for the coil.

Do you have femm 4.2, it's free and ideal for analyzing such a coil structure [axisymmetric] to yield, L, R, and K

In my experience,any coil that has a separated primary secondary, air core, and lies essentially flat is NEVER close to k=1

And with 11.5 inch diameter, you're going to have a LOT of Req in series there.

If you don't feel inclined, post really good dimensions of that coil and construction details, I'll run it through here, give model back to you, so you can start using femm 4.2 instantly while getting a better model for the inductor.

PS: I wind a lot of small 36Awg air core coils and femm usually hits within 1%, with most of that error caused by my dimensions! Try to measure a 1/4 inch diameter coil accurately! femm actually once caught that I had

All the transistor parameters _at_ the operating current ?>:-}

And the stray couplings, and the inductor coupling... which someone mentioned was non-physical?? And on and on... ...Jim Thompson

I forgot to mention, I've created a directory in LTspice for all your files...

C:\LTspiceIV\examples\BaerWhines\ >:-} ...Jim Thompson

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Attachments that your news reader didn't handle correctly.

?-)

Maybe so, but I've never had a problem otherwise.

Jamie

...and that is what i have..

Measures 19 ohms.

Harrumph! I will have you know that us Baers steal piknick baskets in Jellystone National Park!