Selfrunning cold electricity circuit from Dr.Stiffler

[DrStiffler]

Forgot the picture of the underside of the tank. Shows one of the temp probes and the stirrer.

[Mr.Entropy]

Hi Doc,

This power calculation on your drivers page is incorrect.

Wrms = Jc * sqrt( Ton / ( Ton+Toff ))

Since Jc is in joules, you want:

Wrms = Jc / (Ton+Toff)

It still comes out to overunity with the values you measured.

Cheers,

Mr. Entropy

[Mr.Entropy]

According to my calculations I'm only recovering 5% of the inputed 750 mW in my energy harvest circuit. My switching transistor is getting cold ---so where the heck is all my classical energy going?

From your measurements, I calculate 50%, which isn't a conventionally unreasonable efficiency for this kind of circuit.

The transistor getting cold is really wierd, though.  There is a thermoelectric effect, but that can't cause net cooling of the transistor if all the leads are the same metal.  The best it could do is to cool the top while heating the bottom.  Is it possible that the transistor is getting hot on the bottom?

Cheers,

Mr. Entropy

[DrStiffler]

According to my calculations I'm only recovering 5% of the inputed 750 mW in my energy harvest circuit. My switching transistor is getting cold ---so where the heck is all my classical energy going?

From your measurements, I calculate 50%, which isn't a conventionally unreasonable efficiency for this kind of circuit.

The transistor getting cold is really wierd, though.  There is a thermoelectric effect, but that can't cause net cooling of the transistor if all the leads are the same metal.  The best it could do is to cool the top while heating the bottom.  Is it possible that the transistor is getting hot on the bottom?

Cheers,

Mr. Entropy

Okay, how are you accounting for the duty cycle not being 50/50? Would it not be the same in the general sense as that of a squarewave calculation?

[Spokane1]

Dear Mr. Entropy,

Good call on checking for a temperature difference on the bottom of the switching transistor. I shall report after I make some hardware changes.

In the mean time could you review my method of determining how much classical energy is being harvested with the DIAC collection approach.

My method is to merely compare energy (in mJ) between what the storage capacitor dumps compared to how much energy was inputted in the same period of time.

The capacitor dumps every 135 mS. The start voltage is 32 Volts the residual voltage is 22.44 Volts. This is about a  9 Volt differential. With a 200 uF capacitor this means a loss of  5.22 mJ.

In the same time period of 135 mS the Power supply is running at 15.06 Volts at an average current of 65 mA. This calculates to an energy input of  132 mJ.

So 5.22 mJ out/ 132 mJ in  is a pretty dismal 3.9% return on my input.  However this circuit is not quite up to Dr. Stiffler's Specifications and was just being explored until the proper components come in.

Please let me know what I'm missing here.

Spokane1