Quote from: Sprocket on June 20, 2008, 09:33:18 PM
Make no mistake, I do not have a well-equipped lab here, so tend to err on the side of caution with regard to the measurments (ie. use max. rather than avg. current in calcs).  The 400mL is accurate, the start temp was current air temp at time of test, and the end boil-time taken from visual queues - vigorous boiling!

What does my kettle COP come to based on the measurments I posted?  If the COP is greater than 1, you will know my measurments are suspect!   Also, just did another test - different distilled water/baking soda solution, results were:

400mL distilled water @ 15 deg Celsius.
Start Current 1.8A, rising to 4.4A
Time taken to boil very vigourously 190 seconds

Personally, since I heard about "electrode boiler" (which is all this is) I have been looking for any info about the power Mr. Davey's device may have used, but can't find any!  Without some evidence that the power required was unexplainably small, we could well just be dealing with an electrode boiler here...

Hey Sprocket
The COP on thisnew info is 1.07, but due to the quality of the variable data the scope for error is quite large.
The two criteria that is important is the start and end temp, which one needs a digital thermometer. The second is a watt meter. Without this you have to use voltage x amps. Because the amps are moving around and using a start and end amp rating and calculating the average is not quite correct but will give you a ball park wattage.
When one starts moving to ball parks in eccess of 1.5 COP, then more sophisticated equipment will be needed to verify the facts.
Also because a kettle has a 2000w rating does not mean its working at 100% efficiency so one cannot take this into your calcualtions. Rather place the ampmeter around the wires as kettle elements have a constant amp measurement.

As for harmonics of 50Hz they go up in multiples of 50, so 50 , 100, 150 , 200, 250 , 300, 350 etc...Not 50, 100, 200, 400, 800, 1600

Quote from: Sprocket on June 20, 2008, 09:41:35 PM
Aha, thanks, that's what I needed to know!  Also sucks of course 'cos both 'bells' aren't suitable - small one 1000Hz, (after much work!) large one is about 825Hz...  Of course, it also means that there is a valid reason for it not having worked!

I think only one bell needs to be tuned to an octave harmonic or the mains. The other just needs to be at the right distance from the tuned bell to act as a reflector of the waves.

I'm arriving at those frequencies by taking the octave of 50Hz which would be 100Hz then the octave of it which would be 200Hz etc. I think the octaves will be the strongest harmonics of the main but there will be 5th harmonics and others as well, especially when you get in the higher harmonics.

Quote from: storre on June 20, 2008, 08:56:01 PM
The octave harmonics of 50Hz would be 100Hz, 200Hz, 400Hz, 800Hz, 1600Hz, 3200Hz, etc

Don't forget that the USA users need to tune to these possibilities:
60, 120, 240, 480, 960 hz etc.
Paul.

There seems to be a disagreement of sorts on what multiple of the fundamental frequency should be used, a hugely important number imo, if only from the work point of view, as the bell will have to be ground down to this frequency...

Having got no positive results with 1000Hz, I tried reversing the connections, attaching the live to the outer bell, which is closer to the other untried 800Hz harmonic mentioned (bell is about 825Hz).  First little surprise was that the 'character' of the boil seems quite different, much 'smoother' - easier to witness than explain!  Results were:

Time to boil 225 seconds.
current was 1.9A at start rising progressively to max out at 3.2A

At this stage I'm starting to believe that all I really have here is an electrode boiler, so a COP close to 1 is all there is to be expected...

DID YOU HEAR ANY 'BUZZ' SOUND !?

I didn't, and that worry me a lot... Without such sound I suspect only a typical immerse boiler