Joule Thief

[jeanna]

@All,

Can anybody describe how a mains meter works?
I mean the meter the power company uses to determine how many amps of power you are taking from their power plant?

What is the basis onwhich it works?

jeanna

[gyulasun]

Hi,

Here is an explanation, (principle is based on eddy current induced in an Alu disk):

"The electromechanical induction meter operates by counting the revolutions of an aluminium disc which is made to rotate at a speed proportional to the power. The number of revolutions is thus proportional to the energy usage. It consumes a small amount of power, typically around 2 watts.
The metallic disc is acted upon by two coils. One coil is connected in such a way that it produces a magnetic flux in proportion to the voltage and the other produces a magnetic flux in proportion to the current. The field of the voltage coil is delayed by 90 degrees using a lag coil. [1]This produces eddy currents in the disc and the effect is such that a force is exerted on the disc in proportion to the product of the instantaneous current and voltage. A permanent magnet exerts an opposing force proportional to the speed of rotation of the disc - this acts as a brake which causes the disc to stop spinning when power stops being drawn rather than allowing it to spin faster and faster. This causes the disc to rotate at a speed proportional to the power being used.
The type of meter described above is used on a single-phase AC supply. Different phase configurations use additional voltage and current coils."

quoted from wikipedia ( http://en.wikipedia.org/wiki/Electricity_meter ) and the link (1) is here: http://www.usbr.gov/power/data/fist/fist3_10/vol3-10.pdf     Fig.4 PDF page 12

rgds,  Gyula

@All,

Can anybody describe how a mains meter works?
I mean the meter the power company uses to determine how many amps of power you are taking from their power plant?

What is the basis onwhich it works?

jeanna

[Pirate88179]

@ Jeanna:

Yes, it is hard to describe but you did and I understand it now.  I will try that.  if that does not work, I will try it with the JT and the cap where I thought you meant.  Thank you.

Gyula:

Thanks for posting that.  It is a good explanation.

Bil

[jeanna]

@Gyula,
thank you.

@all,

hmmm.
the instantaneous current.
I have seen the formula that uses the instantaneous current. I think it is more accurate. It probably assumes rms.

I suppose in the states instantaneous is 1/60th of a second. Other places it is 1/50th of a second.

In one of my coils an instant is a lot shorter in time. It is 1/52,700 part of a second.

I made a mistake in my table. I forgot to multiply the watts of one pulse by its frequency to get the total watts for one whole second. I fixed it, but I will recheck it before posting.

I am still pondering this.

When current goes back and forth, the magnetic flux pulses. Only the voltage is measured. So, when the current goes back and forth the voltage pulses.

Why can't the current be directly measured?
Does the magnetic flux pulse higher when there are more amps?
And is that amps drawn?
If they are always available, then they should be showing up in the meter, but they only show up when they are being used?

And when they are drawn where do they go if what they are doing is going back and forth?

If some of them are converted to heat or light there would be fewer available for the return trip. But what return trip?

If I use 250mA from my 1.2 volt battery, the volts and 250mA are available to go through the wires of the primary. They do. And they do this on a one way trip to the other side of the battery.

But on their way, they jiggle and jump a lot.

The jiggle and jump is reflected in the pickup or secondary wire which lights leds and now fluorotubes.

What is the amps draw?

It cannot be more than 250mA since that is what is coming out of the battery, no more is available for use.

just thinking... this time while I type.

jeanna

[hazens1]

Update on the 50 LED Solar string light that I got at Menards..

The 8 pin Chip appears to be a logic switch that turns ON the LED string when the voltage from the Solar Panel drops below ~0.5 volts. So no photocell for switching on the string just as I thought.

The Solar Panel is approx 1.5" x 3" and outputs ~2.2 volts directly under a 13 watt CFL. When the sun start shining again I'll test output under direct sunlight.

The Output to the string of leds is approx the same voltage as the battery 1.2-1.4 volts. The LEDs appear to be wired in parallel, so they all must be 1.2-1.5 volt LEDs. I've yet to measure current draw. Will do that soon, need to make an adapter to place in between the string connection and the Solar box.

I should be able to wire a JT circuit to the output of the Solar charger/battery combo box.