PhysicsProf Steven E. Jones circuit shows 8x overunity ?

[nul-points]

133 uW in and 52 uW out seems like reasonable performance for a Joule thief. The rest was not clear to me. I will have to look at it for a while.

i agree that "133 uW in and 52 uW out" is  reasonable performance for a JT

however, these results for a variant of Steven's circuit are showing 81uW in and 133uW out - 212uW out if you include the LED o/p!

[nul-points]

null-point : awsome work. Any chance to create a second circuit like first one ? instead looping just attach C2 in to C1 out. I'm not expecting to get some specific output at C2, just curious what will happen. Thanks.

thanks Tudi - i have done something similar with a different circuit in the past, so i'll try to move on to that

at the moment tho', i'm just monitoring the voltage trend on the supply cell & buffer cap

i believe that NiMHs are only 50% efficient when you charge them, so i'm not expecting too much of the present setup (would need COP = 2 just to keep cell charged - but LED dissipates 79uW so now have COP < 2)

anyway, this might be more evidence for Steven - we'll have to see what he thinks about this data

all the best
np

http://docsfreelunch.blogspot.com

[hyiq]

I agree Chris --
1.  "This circuit is a very unusual circuit." 
2.  "We need to keep the current down for this effect."
3.  "Sometimes it seems to be looking really good then other times it does not. "

I have had the "glitch" in one session on the Tek 3032 myself a while back, where the circuit was performing very well, n>1 per the Tek 3032.
  I made measurements of Pin and Pout repeatedly, back and forth, and kept getting n>1 for about 45 minutes, varying Rr and Ro, and getting variations in n but always n>1.   
Then all of a sudden, it changed for unknown reasons to n<1.   Sorry I did not mention this sooner -- I thought the "glitch" was for it to fall out of the super-efficiency condition temporarily, or perhaps I caused an inadvertent short in the system -- I could not find what made it glitch.   Later, it looked fine again.


During this same session at the university lab, I tested the build by my friend Les Kraut.  He tried to replicate the sj1 circuit exactly.   His build showed n ~ 8, after the "glitch" showed up in my initial circuit-testing.


Later -- I have felt one of the resistors being very hot to the touch during a run, and this MAY be a reason for the "glitch". I was not at the Tek 3032 this time.   I suggest feeling the resistors if your circuit "glitches" again.

Clearly the goal is to understand our observations and to keep the device in the super-efficiency condition.
Thanks again, Chris, and my apologies for not mentioning this sooner.  I do not think this "invalidates" the circuit, but it is something we must try to understand.
Steven

Hi Dr Jones,

yes, this is correct, I have observed the same. I was thinking my scope was on the blink, it samples @100mhz so I thought this should be enough, but was getting inconsistent readings.

My Bi-Polar Circuit version seems to be the dud however, it draws too much current and so far it seems to loose the effect. I will keep working on it as if I can get it working then its only a diode or two and it should self loop.

I am up with a fresh start today so will see what the old brain can come up with today.

All the best

  Chris

[gyulasun]

....
@Gyula - Yes, I fixed as you Xee2 suggested. Would you suggest a diode on the negative rail? This may help any ripple?
....
  Chris

Regarding the small power levels involved in this circuit, the good old germanium diodes like 1N34, 1N34A  or also some ancient germanium European types like OA160, OA161, OA5 etc could be used. If you happen to have any germanium bipolar transistor left somewhere, you can use it here also as a diode, by connecting its base to its collector and it will be the anode and the emitter will be the cathode (for an NPN transistor of course, for a PNP they reverse).  Only drawback is the much lower reverse voltage capability due to the 5-7V or less base-emitter reverse voltage ratings.

With such diode any AC that might come from the circuit direction via the negative rail (or the positive if you place the diode there) will be half-wave rectified, you may wish to move the C3 filter further towards the battery in this case so that it should not shunt any AC before the diode.

Gyula

[hyiq]

Adding diode here will help some.

Hi Xee2,

Thanks for your suggestion. Circuit Schematic is attached. I put that this is experimental as I had the POT on the positive rail and the effect was lost so as I have not yet tested this circuit its experimental. I will test it today though.

All the best

  Chris