Odd/Crazy output transformer design?

[LinuksGuru]

Second: I spoke with my winder and the two cores could differ in quality because they come from different manufacturer.
I think this will be the answer to my problem.
Tyimo

The difference is just too big.

Did you measure turns ratio as I told in one of my previous post? What is the # of turns (you give to winder in sections) 1 and 4 for example? If # of turns is different, I suspect wrong polarity of connections between these sections.

 

[pieter t]

LCR4080 can't measure inductance lower then 0.1H, therefore, its impossible to check with it leakage inductance.

LinuksGuru,

In your post #90 you were wrong a factor thousand, now with the LCR4080 specs you are wrong a factor one million.....
This meters measures from 0.1uH on upwards.
Is it so difficult to read specifications well?

 

[LinuksGuru]

LinuksGuru,

In your post #90 you were wrong a factor thousand, now with the LCR4080 specs you are wrong a factor one million.....
This meters measures from 0.1uH on upwards.
Is it so difficult to read specifications well?

I took specification from this company which lists them on site for sale, look at the screenshot attached:
Conrad Electronic - Europe`s leading electronics and technology online specialist

Sorry if they are wrong.

 

[miklos]

This looks good to:
Portable Handheld LCR L C R Meter 0.3% accuracy TH2821B | eBay

 

[pieter t]

I took specification from this company which lists them on site for sale

Sorry if they are wrong.

The Voltcraft site has the right specs.

 

[pieter t]

This looks good to:
Portable Handheld LCR L C R Meter 0.3% accuracy TH2821B | eBay

Yes, but I guess that the specified inductance range at 100Hz/120Hz is wrong (should be up to 9999H in stead of 9999uH).

 

[digits]

Dude you can build a 1% tollerance L/C meter for like $10. I'm still useing the old design from the internet with the PIC16f84a with the seperate comparator chip, but there is a newer design out with a newer pic which puts everything inside the chip, appart from your reference components and PSU. You don't have to know anything about microprocessors, just buy or wire up a cheap programmer and load the chip with the programs you'll find with the designs...

 

[Tyimo]

Hi Linuksguru!

Did you measured output voltage on secondary if transformer (with progressive winding) is connected to sine-wave generator?
I think trafo with progressive winding have incorrect polarity connection between sections 4-1 and 3-2. If you feed 1KHz signal from the generator to A1-A2, and measure voltage on secondary loaded with let's say 100 Ohm resistor, you could calc by output voltage if my version is right - and I'm 99% sure it is (assuming cores and number of turns are the same, and 2nd core is not defect).

Yes, I checked and everything was all right. Every winding has the same Induction and voltage, and they are connected well to each other.
My winder will make again the OPT, but now with the original iron what was used for the previous and good working OPTs.
I think my problem was the different iron material, lamination and the different shape of the iron (what could cause different magnetic length - mean circumference of the core). Or something else...
greets:
Tyimo

 

[Tyimo]

Thanks to everybody for the L/C meter tips!
First I will try Dave suggestion.

the easiest thing to do to measure at lower frequencies is to use line voltage through a variac. Place an ac ammeter in series and then you can calculate the impedance. If done at 50 or 60hz the impedance will be predominantly inductive in nature so dividing the Z by 2piF nets you the L

Say with 100V across the winding you get 10ma of current. 100/.01= 10,000 ohms impedance. 10,000/2/3.15/50=31.8hy's

Tyimo

 

[xpl1c1t]

Progressive winding used to decrease layer to layer capacitance. For example: 10 turns forward, 9 turns backward (see picture attached). Another benefit of this kind of winding that it is possible to distribute very smoothly large number of turns in single section.

However, properly designed audio frequency toroids don't need it. In other words, its possible to avoid this increase of complexity without sacrifice of product quality.

Before i read this post I was going to drop the idea of hand winding a toroid output transformer simply because it would be too painstaking to get those hundreds/thousands of feet through the damn donut hole every wind.

This makes it quite an easy task. Thank you linuks!

 

[analog_sa]

This makes it quite an easy task.

Why?

 

[TonyTecson]

Before i read this post I was going to drop the idea of hand winding a toroid output transformer simply because it would be too painstaking to get those hundreds/thousands of feet through the damn donut hole every wind.

This makes it quite an easy task. Thank you linuks!

you need something like this...shuttle can be made of plastic or wood, must pass thru the hole of the core....good luck.....

An externally hosted image should be here but it was not working when we last tested it.

 

[TonyTecson]

Please note that progressive winding to lower layer to layer capacitance only tackles one of the capacitive components in a transformer.
The primary by itself also has a capacitive component, the longer the wire the more capacitance.
Therefore choosing a big core with "little" copper is IMHO always better than a small core with "much" copper (apart from nowadays catastrophic copper prices!).
With the big core / little copper combo the lower capacities and DC resistances (copper losses) make better transformers.

thanks, will keep this in mind.....
what is the downside for not utilising the full winding window?