OverUnity prize money 15825 US$ total until now

[MileHigh]

Hi Poynt,

If you dig into the spec for the ultracap you will probably find something about internal leakage current such that they self-discharge to a certain extent.  I am not sure if it is linear.  I am pretty sure I read up on supercaps and how they work.  They work in a manner akin to a charcoal filter, with a lot of surface area per unit volume, with one of the trade-offs being leakage.

It blows my mind that you can get a 650 farad capacitor, even if it is low voltage.  Can you say electromagnetic rail gun?

Anyway, there is always the issue of the number of time constants the coil is switched on in a given JT circuit and if you are dissipating too much energy resistively.  Fun fun!  lol

If I had a 650 farad cap and assuming that leakage was not an issue, I would put an inductor across it such that it resonates at about 1 Hz.  Then check each day with a scope and see how long that baby lasts!  Then I would make an assassin's electromagnetic rail Bic pen gun!  Nerd heaven!  lol

MileHigh

[poynt99]

MH,

The leakage current for the 650F model is a whopping 1.5ma 

LOL, .99

[WilbyInebriated]

Stefan,

How will you measure this GJT to ensure at least 1W of power is being supplied by its output?

I would not rely on the specification of an LED. LED's can run on a wide range of voltage and current inputs, above its minimum. You can run a LED off 20mW or so (i.e. 10mA @ 2V).

I would suggest dispensing with LED's as an output power indication in favor of a 0.5W or 1W suitable value* carbon resistor. Do a control test with a DC supply and see what temperature the resistor is at with 1W input power. Then monitor the resistor's temperature for the DUT test to ensure it remains at that temperature, or higher. *A value that results in a temperature rise of say 20 to 40ºC above ambient.

As a side note, the applicant would be wise to tweak the submitted device to put out the amount of power he thinks will make the device last the 3 months and still maintain the minimum 1W output.

An AA battery should be able to source 1W of power for about 3.75 hours (assumed 1.5V output). This control test being with a standard Ohmic load, for example a 1.5 Ohm resistor. At this point, the battery would have fallen to a certain percentage of its full charge voltage. The battery however is not fully depleted of its energy.

It should be noted that using this same battery in a step-up circuit such as the JT, the time duration of this 1W output power can be extended quite a lot for two reasons:

1) The average load current on the battery is lower than with the control test, and

2) The JT facilitates access to more of the battery's stored energy, depleting it far beyond what the control test will while still being able to maintain the 1W power output.

I estimate therefore, that the AA battery would be able to charge the 650F cap from 0V to 2.6V about 8 to 10 times using the JT to charge it.

So I would suggest the temperature monitored resistor as the output power indicator (use a thermistor attached to the resistor), and see how long the GJT can keep the heat on. This will require some tweaking of the switching circuit which dumps some of the cap's energy back into the battery, such that it does so before the resistor's temperature drops below the required minimum.

For a 1W constant load, I will be surprised if this circuit (powered by a 2500mA AA battery) lasts more than 10 hours, which is a little shy of 3 months.

.99

this idea is, with respect, asinine. why would you change something designed to create light into something that creates heat just for measurement purposes?
this is a poor approach and i might add, lazy. if the DUT is designed to create light, then measure that. don't go swapping parts out and pretending it behaves the same. a led is not a resistor... converting/perverting it to something that is easier, more convenient for you to measure is 'lan dan jiang'...

[hartiberlin]

Hi,
I would test it
1. in comparison with the same LED being driven by DC voltage,
so optically comparing the brightness level, which is pretty exact with
the human eye.

2. by using a calibrated resistor, which will heat up calorimetrically
some destilled water and see, how much heat energy this will
put out over time.
This is also a very precise measurement and can be used to see, how much
temperature difference the water will have afther the test and this way
you can calculate the energy spent to heat the water and thus the output
energy of the JT circuit.

P.S: Gadget should do these tests already by himself before applying for
the OU prize.

Regards, Stefan.

[poynt99]

The heated resistor and water is along the lines I was proposing Stefan.

Just ensure that the 1W minimum power output is achieved by using a DC control.

P.S: Gadget should do these tests already by himself before applying for the OU prize.

Precisely. Will he?

.99