[TowerTalk] Emotator Rotator

[Roger Parsons]

Well, now I don't know. I believe that for proper operation the phase in the secondary winding should be 90 degrees different from that in the primary winding, and that the voltage across each winding should be the same. These conditions seem to be met by the original Emotator circuitry.

With the extra 14uF capacitance the phase difference is about 120 degrees, and the voltages are still quite equal. The motor runs.

I tried adding an extra 110uF of capacitance using two back-to-back elecrolytics. In one direction the phase was about 90 degrees, but the voltages were very unequal. Nevertheless the motor ran. In the other direction, the phase was about 180 degrees, and the secondary winding voltage was very low indeed. The motor did not run. I then tried again with a different pair and type of capacitor with the same result. (Whilst I have seen the series connection for electrolytics described, I must admit I am a bit dubious of it, particularly if a substantial current is required.)

I then remembered that I had an enormous 16uF HV capacitor (for some unknown reason), so I tried that for 30uF total. Results were pretty similar to the 14uF case, but with more voltage difference.

There has to be an optimum value of capacitor for any circuit of this nature, as the phase change is dependent on the inductance of the winding, and the value of the capacitor. Of course, I don't actually know the value of the original capacitor, although some Emotator rotators seem to use values of 10uF or less.

So I am not at all sure that I am any further forward. Perhaps I will have to wait until I can get the rotator down and check out the capacitor.

But again, many thanks for the help.

73 Roger
VE3ZI