UFO politics Keeps his word 12-12 12 Let the games begin.......

[TinselKoala]

I've seen tinman's videos, very interesting indeed. Right now my only response (that I sent to tinman in a PM) is to link Professor Lewin's lectures here:
http://www.youtube.com/watch?v=eqjl-qRy71w
http://www.youtube.com/watch?v=1bUWcy8HwpM

I don't think Tinman is doing anything "wrong". His measurements are showing how we must really be careful measuring power in circuits with pulsed power and high (relatively) inductances.

I spent an hour winding a fresh Tesla bifilar pancake coil; not as much wire as in tinman's but a start, I'll wind another one with more wire now that I've got a technique down.

Please.... I need to see a sketch of the schematic of the LED/Cap/diode board, I can't figure it out from the verbal description. Once I'm sure I'm using the same circuit as Tinman I can apply some scoposcopy to it and see if we can figure out what's happening. I think my signal generator can substitute for TM's oscillating power supply.  Meanwhile, Lewin's lecture material is important, I think.

But this:  Quote from jason65r-Kogs.

I to read that post. I'm really not happy with the tone of it. It is sad, but I expect there always will be a group of loud mouthed know it alls (who don't know anything) ready to mud sling when they don't understand something.

I'm really not happy with the tone of that post, ho ho ho. It is indeed sad, but I can't recall anyone here personally insulting the arrogant ignorant bunch of naive idiots over there..... YET..... but if that's the way they want to play, I can play that way too.

[picowatt]

Things I don't like about the latest torque tests:

1.  The brake setup has too fast of a temp rise likely causing coefficient of friction to change as it heats.  A wider drum with a metal band would increase the surface area of the brake, slow T rise, and provide a smoother more consistent braking force.

2.  Capturing video frames to freeze measurements does not take into account that not all readouts (meters/scales) are updating at the same time, and therefore not necessarily providing numbers that reflect "simultaneous" measurement.

3.  Number 2 above is likely further exacerbated by number 1 above.  The braking force and RPM must be held constant long enough for the meters and scales readouts to stabilize.  This requires a smooth and steady brake.

4.  I have never been a fan of two scale dyno setups like this, but would be more impressed if a fixed preload with equal scale readings was applied prior to each run and then the applied pressure calculated via the difference in the scale readings as noted during a run.  If RPM and indicated load vary during a run, more work is needed to improve the brake.

5.  The ammeter should be verified with a shunt and a low pass/voltmeter or a scope to confirm the ammeter's readings.

6,  Even if precise quantification is not possible with the present setup, comparisons can be made to a stock motor.  What efficiency does a stock motor indicate under similar testing?

As I said, I have never been a fan of these two scale dyno setups.  A single arm Prony using a single scale can easily provide the motor shaft lb-ft of torque and then horsepower is simply (RPMXlb-ft)/5252.

That digital torque wrench adapter he has would be a great start, but I would use it to measure the torque right at the motor's shaft axis.  This would require modifyng the brake so that the braking force is axial to the motor shaft.

Using an AC induction motor with a bit of DC applied for use as an eddy current brake as in my previous post makes a quick and dirty axial brake setup.  Attaching the digital torque readout to the induction motor housing so that its centerline is the same as the induction motor shaft centerline would provide a direct readout of shaft torque in lb-ft, and again, horsepower would simply be (RPMXlb-ft)/5252.

Alternately, a small disc or drum brake setup could be incorporated.

Many in the "one-lunger" crowd just use a single arm made of oak that is clamped, using wingnuts or bolts, to a drum mounted to the motor's shaft.  The end of the arm rests on a scale or is hung from a spring scale.  The scale readout is divided by the length of the arm in feet to arrive at torque in lb-ft and (RPM X lb-ft)/5252 is used to calculate HP.

I truly hope UFO improves on his dyno, or at least compares a non-modified motor using the same setup, I am indeed curious to see what his modified motors and all his hard work can do. 

PW

 

[picowatt]

...I can't recall anyone here personally insulting the arrogant ignorant bunch of naive idiots over there..... YET..... but if that's the way they want to play, I can play that way too.

I believe you just did...

PW

[TinselKoala]

I believe you just did...

PW

Irony is hard to convey in forum posts, isn't it.


I suppose I rewound my first DC motors (Mabuchi and Johnson 'can' motors) nearly 40 years ago, to win slot car races. It was fairly common practice to improve torque and top RPM, to strip the armatures and rewind with heavier wire, fewer turns, and epoxy the wire in place so the motor wouldn't "throw wraps" from the extreme RPMs attained. Of course we were running on the track's supplied DC power so we didn't care much about input power, we just wanted fast acceleration (high torque) and high top speeds for the races. And if the motor lasted a day, that was just fine.
Another thing that might seem crazy, but actually works, is to run the motors completely underwater for an hour or so. This "sets" the new brushes so that they make full contact with the commutator.
Of course after doing this the motor needs to be dried well and re-lubricated.

[poynt99]

I've seen tinman's videos, very interesting indeed. Right now my only response (that I sent to tinman in a PM) is to link Professor Lewin's lectures here:
http://www.youtube.com/watch?v=eqjl-qRy71w
http://www.youtube.com/watch?v=1bUWcy8HwpM

I've done Lewin's version of the experiment, and I found that he has mis-interpreted the results he is seeing, and as such, misled his students. Unfortunately, Lewin is comparing apples and oranges when he states that Kirchhoff "is for the birds!", and "Faraday is the only law that matters!".

According to my results, KVL indeed DOES hold in this experiment, but you must know what to measure and how to measure it properly and completely, which unfortunately, Lewin did not do.