Simple to build isolation transformer that consumes less power than it gives out

[poynt99]

I also looked at the power fact P.F. -- for the input, it shows as approx. 0.6  -- and it varies, 0.5 to about 0.7.  (The input power comes from a dimmer, which is connected to the mains.)

Ah, yeah. That's a definite no-no if you expect to be able to measure accurately with the meters you are using. Not even the clamp meters will measure accurately with a chopped up sine wave.

Could this be why the P3 meter is having difficulty getting the AC amps (and the power)?

Definitely!

How does one measure the current accurately -- or better, the power -- when the PF is not 1.0?

Buy a variac!

[JouleSeeker]

  I have and have used a variac, with this very system Poynt, as I've discussed earlier on this thread.  But as Lynx noted, it may be that a spiked voltage is better for the response (better than simple sine-wave). 

  I may have to go back to the fancier DSO, and use P(t) = V(t) * I(t), getting the power moment-by-moment, thus getting the power waveform.  This can then be integrated to get the total energy; also the average power.  I was hoping the simpler meters would do the job, but evidently not for PF<1 and for non-sinusoidal waveforms.  It's an old problem. 


For the output power, I still prefer calorimetry -- simply heating water with a resistance.  Power = Q(heat) / Time.

Or, if one could get Jack's circuit to work ou with sinusoidal waveforms and PF=1, then this should be easy to measure.
Any other ideas?

[poynt99]

If you feel that a spiked voltage (not sure where or why) is better, then yes you will have to resort to using a DSO if you want to measure the power accurately.

What were your results when you used a variac?

[T-1000]

@T-1000

Well, the problem is with this set-up that the output transformer E-F-G-H was starting to give some slight smoke so I stopped the video. I will start again tonight and make a clear connection diagram and do some tests at lower voltage off the Variac. But again, my diagram is good for my transformers and may not apply to others.

That looks like you are trying to use 2 primary coils on same transformer and they got connected in parallel but on such way they create max load to each other inside of transformer. Try to connect one of them in reverse order and see if you still get max amperage used without load. I strongly recommend to connect lightbulb in series for fuse element before Variac so in case of short circuit /max load on idle transformer your lightbulb will be lit brightly.

Cheers!

[NerzhDishual]

Hi OU Dot Com Blokes,

AC Input vs AC Output power measurements... what a nuisance! 
These "kill a watt" cheap meters seem to cheat us.
Why not using at least DC input? With a DC bat and an inverter, for ex.
First "calibrate" = figure out the efficiency of this device and then take account  of it for
the COP calculations.

BTW: this could also be used for any Sonic Boiler...

--------------------
I played with:
1) A 1 to 1 small trafo (measured Henries: about 0.350 H primary and secondary).
2) A signal generator (see picture) (and also an home made 555  +  Mosfeet square wave gen).
3) And old hammeg HM207 scope.

I have noticed that, with *square* waves:
These square waves "morph" into nice sine waves when you approach the resonant freq of the
trafo (about 170 KHz in my case). A trafo as also some (small) capacitance. No?
When I reach this very freq the 'peak to peak' voltage is multiplied by more than ten.
Beware: no load here! No 'OU' claimed.

Anyway, I did not know that you can transform square waves into (more apparent 'voltageable')
sinus waves with a mere 1:1 trafo should you reach the right freq. Did you?
Of course, with a sine wave you can also observe a voltage multiplication at resonance.

Very Best from Brest,
Yann