With permission and encouragement from forum members elias and gyula over at Energetic Forum: Hi
Most of you know about the Hall Effect: Hall effect  Wikipedia, the free encyclopedia
This effect is widely used for sensing, but has it been thought to use it as an energy generation method? As it seems the the output energy flows perpendicular to the input energy, and seems to be more affected by the energy of the magnetic field, rather than the supplied current.
When we have got a conductor, and pass a current through it, the current can be deflected by using a strong magnetic field (e.g using a strong Neo Magnet) and a potential difference occurs perpendicular to the current flow. So can this potential difference used as an Energy Source? Any ideas? It seems that when we have got a current draw, a force can be applied by the magnetic field to create a potential difference which can provide energy. The question is: How much energy can be generated this way to surpass the energy needed to keep the current flowing. By using a very low voltage source, high currents can be generated by very low power levels.
I think that this system if properly designed can become a COP > 1 system.
To increase the potential difference, an ntype semiconductor is the best choice as it gives a very good potential difference.
I don't have ntype semiconductors at hand, any suggestions for buying?
Elias Hi Elias an All,
I have done some search on manufactured Hall sensors that are also called as Hall generators. For instance this firm, F.W. Bell produces some type, see this link: fw bell products
At newark.com there is some of the Bell products but with a min 26 days leading time (they do not stock it): More Test & Laboratory Equipment  Newark.com
Let's examine the most sensitive type, the SH410 which is US$20.39 at Newark (with 26 days Lead Time).
Here is the data sheet: http://www.fwbell.com/PDF%20Documents/SHseries.pdf
Suppose we get such device with the following parameters:
Rin=400 Ohm (ranges between 240550 Ohms) Rout=400 Ohm (ranges between also 240550 Ohms) Sensitivity ranges between 292  1120 mV/kGauss, let's pick a 300mV/kG Nominal input current In=5mA
Now let us use a magnetic field of 1Tesla (10kG), this is an assumption from me that this device is able to operate at 1Tesla, data sheet does not give this data for this device), this gives 300mV*10=3V unterminated output voltage.
Using 5mA DC input current from a current source, input power is
Pin=0.005*0.005*400=0.01W=10mW
Because we want the highest output power, the output must be terminated with the same value of resistor as the output resistance itself, so I assume a linear relationship and the output voltage will be halved: Vout=3/2=1.5V DC So the output power is
Pout=(1.5*1.5)/400=0.005625W=5.62mW This gives a COP=5.62/10=0.562
If you receive an SH410 which happens to have the specified 1120mV/kG sensitivity (from data sheet), then the unterminated output voltage at the 5mA input current and at B=1T comes out as 11.2V, half of which is 5.6V. So assuming the same input and output resistance, the output power comes as: Pout=(5.6*5.6)/400=0.0784W
This gives a COP=0.0784/0.01=7.84 sounds quite a nice COP number!
Notice that half of the output power is dissipated in the device itself i.e. in the latter case 0.0784W heats the Hall device and 0.0784W is dissipated in the 400 Ohm terminating resistor.
I have not considered pulsed input current operation that gives pulsed AC output voltage.
I hope I did not make errors in the understanding of the data sheet and in calculations. IF you notice errors, please correct it. This Hall sensor so far seems an off the shelf device that has a COP possibility higher than 1.
Remark: In case the input resistance changes to a lower value when you connect a load resistor across the output, then input power should be revised again (though using a true current generator operation, this may be minimised?).
rgds, Gyula This is a great find Gyula.
I read the datasheet. Because the input and output impedance is the same, and the voltage output of the hall device is dependent on the input current, then the only thing that matters is the magnetic field strength, after a certain magnetic field strength the system becomes COP>1.
For example considering SH410, in a scenario we would provide the device with 20mA @ 10V (assuming 500ohms of input and output resistance) Pin = 200 mW. Note that at maximum input current we have maximum sensitivity. So by considering a sensitivity of 1760 mV/kG, for 1 Tesla we have got 17.6 Volts at the output, so Pout = 17.6*17.6 / 500 = 620 mW, so COP = Pout / Pin = 3.1
But, we need to make usable power, so if we use a 500 ohm load at the output, we can produce about 154mW of usable power. The beauty is that we can increase the COP, by simply using a more powerful magnetic field. if we double the magnetic field strength the usable power at the output would become 620 mW, thus yielding to a real COP of 3.1.
So by using a more powerful magnetic field and a more sensitive device, we have can increase the COP of the system.
This is really remarkable, somebody really needs to experiment with these devices.
Elias tak
