Thane Heins Perepiteia.

[polarbreeze]

Didn't they see the same anomoly in earlier experiments with current around the 2 amp range? Where both voltage and current dropped?

Maybe, I lost track of that. But I think that's a much different situation: 2A versus 10mA. They could have been saturating the core at 2A for example. I really think the most important thing right now is to measure that input current in the latest batch of experiments with sufficient accuracy to draw conclusions from. We can get some unambiguous results very quickly that way - not only for efficiency but for Thane's #1 experimental goal that the primary coil should not draw additional current when the secondary is placed on load. It's very encouraging that the answer is so close.

PB

[MeggerMan]

@Thane,
Looks good so far, MEG look-a-like perhaps?

60Hz input implies you are using a low voltage mains transformer (say 110V AC to 3V or 4.5V AC or 240V AC if you are not in the USA) to supply your experiment, is that correct?
At least at 60Hz it should not upset the meter reading too much, and a true RMS meter should be fine.

The center winding is on a slab ferrite rod, yes?
Is the load resistor wire wound, and if it is try using lots of carbon resistors in its place, just in case the winding in the resistor is effecting the results.

Calorimeter Test:
Here's a suggestion: place the load resistor wrapped in PVC or waterproof it somehow, into a 1Litre container of water placed in a polystyrene filled box or something insulated and measure the temperature rise to get the energy in joules.
You could also work out a load resistance to match the input power readings and do the same test so that you have a comparison of true energy in and out.

What is the toroidal transformer you are using Vin / Vout and power?
I have a similar large toroidal, 240V in 2 x 55v 500VA I bought years ago but it does not have the winding nicely split like yours, its wound 360 degrees with no apparent gaps.
However I do have some big cores from the Bob Boyce project that would be ideal.

One more thing, 0.01A on a 10A scale is very bad news, this should be 10mA on a 100mA scale ideally.
Because you test #5 could read (worst case based on dropping overflow digits):
Input voltage = 1.104 v
Input current = 19.5mA
Input power = 21.5 mW

Output voltage = 4.24 v
Output current = 4.24/990 = 4.2mA
Output Power = 17.8 mW

Efficiency = 82%

Saying that, I cannot understand the drop on input power when you put more output windings onto the load only that unless they were shorted before being separated and attached to the load.
One of my meters I have is a Tenma 72-7760 Professional DMM with true RMS on AC current and voltages.
No clamps needed.

Regards
Rob

[markzpeiverson]

What about these meters?

http://www.fwbell.com/Content.aspx?Page=200

FEATURES:
* True RMS measurement
* Measures low level DC & AC currents from 0 to 2000 mA with resolution as low as 0.1 mA.
* Frequency range DC to 100kHz
* Built in 3 1/2 digit display
* Simple clamp-on operation
* Supplied with hard carrying case
* Basic DC accuracy of 1% of reading
* Built to IEC 1010 safety standards/Approval Pending
* BNC analog output for connection to oscilloscope or recorder

Or, use a power meter and don't worry about calculating power; many even calculate power in the harmonics:

http://www.powermeterstore.com/p5834/accuenergy_acuvim_l_power_meter.php

The Acuvim-L series meters are multifunction power meters manufactured by Accuenergy. It is the ideal choice for monitoring and controlling of power distribution system. Some of the features and electric power parameters available on the ultra-compact Acuvim-L are:

True-RMS measuring parameter
4-quadrant Energy
Power Quality Analysis
Over limit alarm
Energy pulse output

Acuvim-L may be used as a data gathering device for an intelligent Power Distribution System or a Plant Automation System. All monitoring data is available via an optional digital RS485 communication port running Modbus Protocol.

The quality of the power system is important with increasing use of electronic loads such as computers, ballasts or variable frequency drives. With the Acuvim-L power analysis option, any phase current or voltage can be displayed and the harmonic content calculated.

By knowing the harmonic distribution, action can be taken to prevent overheated transformers, motors, capacitors, neutral wires and nuisance breaker trips. Redistribution of the system loading can also be determined.

[JustMe]

Hey where's our nightly update? Luc better not be starting any sleeping or eating or stuff like that...

[gotoluc]

Hi all,

since many are wondering why we have chosen to use a clamp meter to measure our amps in here are some of the reasons.

We have 6 multimeters at our disposition. The one from the University (true RMS) has 2 scales, 0-2 amps and 0 to 20 amps. When we use it on the 0-2 amps side our output voltage drops by 40%, so that's not good. The 0-20 amp side has about a .4 volt drop but not much resolution. Thane has 5 others meters which 3 of them are the same and I have compared them to the University meter and they give accurate readings on their 0-10 amp scale and only drop the voltage by .2 volts but like the University meter on the 400 ma or lower scales it drops the output voltage by 30%, so also not good. The same story for Thanes 2 other cheaper models.

So we decided to try a clamp meter since they have no effect on input or output voltage. When I got I the New clamp meter I checked it against the University model on the 0-20 amp side and also Thane's 3 good meters on the 0-10 amps and in all cases the clamp meter gives a higher reading and no voltage drops, so that is good.

We want to stay with a clamp meter since we will have 1,000's of more tests to do and also on different things like generator coils, so it will make our moving the meter around much easier and also not effect or results. I know we need a more accurate one, we just could not get a milliamp clamp meter in stock in our city but we now have on order a True RMS Milliamp clamp meter, it could take 10 days or more to get it though, so please be patient and do not conclude we are trying to fool people, we are real and we also want real results as much as you.

Here is the link to the meter we ordered: http://www.prova.com.tw/E_PROVA_11.html
Here is the link to the meter we have: http://www.prova.com.tw/E_CM_07.html

At this time the efficiency of the Toroids are in the lower input voltages but if I get it to work better this Sunday I will push the volts in as hight as I can go and stop it at a 101% and we will post the results of the low and high points.

Stay tuned

Luc