Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com .
I bought some T-37's and T-50's. The problem is... they're not color coded,
and not identified by mix. So I have mystery toroids T-37-?? and T-50-??...

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

Thanks for all assistance.

Jim Shrum - KC9FFX

Look at the tables in the ARRL Handbook, in 2003 it was in Chapter 24, for
tables with the info you need to calculate the inductance on a given core
with a certain number of windings. You need to solve for AL obviously since
you want to find your core.

Uwe

in article , J Shrum at
wrote on 4/21/04 18:55:

Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com .
I bought some T-37's and T-50's. The problem is... they're not color coded,
and not identified by mix. So I have mystery toroids T-37-?? and T-50-??...

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

Thanks for all assistance.

Jim Shrum - KC9FFX

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

The equation goes;

Turns = 100SQR(uH/Al) where Al is the inductance in uH per 100 turns)

and

15 = 100SQR(150/Al)

and (0.15)^2 = 150/Al

and

150/0.0225 = Al = 6666.

You have ferrite not powdered iron.

For Ferrite, it's just the conversion

Turns = 1000SQR (mH/Al) where Al = mH/1000 turns

15 = 1000SQR(.15/Al)

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

W4ZCB

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

And the T37 core, at 2200, looks like 75 material, look out for it's bulk
resistivity which is pretty low.

W4ZCB

and
0.15/0.00225 =66 which looks like, (for T50 core) material 61

And the T37 core, at 2200, looks like 75 material, look out for it's bulk
resistivity which is pretty low.

W4ZCB

"J Shrum" wrote in message
news
Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com
..
I bought some T-37's and T-50's. The problem is... they're not color
coded,
and not identified by mix. So I have mystery toroids T-37-?? and
T-50-??...

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH

Al = 150uH * square(1/15) = 667


T-37 9turns 30awg = ~180uH

Al = 180uH * square(1/9) = 2200


See if these Al values look realistic. Even if not, this is the value of
inductance of one turn for the core which some manufacturers used as Al many
years ago when I worked with the devices. The inductance ratio varies as the
square of the turns ratio.

John

Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com .
I bought some T-37's and T-50's. The problem is... they're not color coded,
and not identified by mix. So I have mystery toroids T-37-?? and T-50-??...

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

Start at http://www.amidoncorp.com/aai_productselection.htm

Follow the "Iron Powder Cores" and "Ferrite cores" links.

The formulas, and the specific inductance index A(L) values for
various toroid formulas, are on those pages.

It's important to note that the A(L) values are stated in different
units for the two toroid types. For iron-powder cores, it's given as
"microhenries for 100 turns", while for ferrite cores it's
"millihenries for 1000 turns".

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On Wed, 21 Apr 2004 17:55:20 -0500, "J Shrum" wrote:

Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com .
I bought some T-37's and T-50's. The problem is... they're not color coded,
and not identified by mix. So I have mystery toroids T-37-?? and T-50-??...

If they are not color coded then I guess they aren't Amidon toroids,
at least all the Amidon toroids I have seen were color coded, Amidon
does have all the specifications for all their toroids posted on their website
though:
http://www.amidoncorp.com/aai_productselection.htm


The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

If you are running Windows, you can use this program to do
quick inductance calculations for many different toroids types:
http://www.qsl.net/dl5swb/minirk_e.htm , and to get specs on
different toroid types. A real time saver for calculating the inductance values
and it also shows the Inductance Index for each toroid and the frequency
bandwidth for that composition type, which might help you to get a better
idea of the composition type of your toroids. I think it will still be hard to determine
the composition types for certain, although the different composition types do have
different Inductance Index values for the same size toroid.

There are lots of web resources. Here's one:

http://www.amidoncorp.com/ace_iptcforrf.htm

And another: http://www.bytemark.com/

You can search for Amidon or Bytemark or Fair-Rite or Ferronics, and
also just search for 'powdered iron toroid' or 'ferrite toroid' and
find lots of things. Those links will take you more-or-less directly
to Al values for a wide range of cores. Just remember that inductance
goes as the square of the number of turns, so if Al is uH/100 turns,
the inductance will be Al*(your_turns/100)^2.

Cheers,
Tom


"J Shrum" wrote in message ...
Greetings,

Recently I bought a grab bag of mixed toroids from www.allelectronics.com .
I bought some T-37's and T-50's. The problem is... they're not color coded,
and not identified by mix. So I have mystery toroids T-37-?? and T-50-??...

The question is, is there a way to come up w/ a rough estimate of the mix
value? I wound some test coils and come up w/ these figures:

T-50 15turns 30awg = ~150uH
T-37 9turns 30awg = ~180uH

Perhaps there is a chart or something similar somewhere that I have
overlooked that will give me an idea.

Thanks for all assistance.

Jim Shrum - KC9FFX

Use program TOROID from website below.

Enter into the program the data you already have, core dimensions and
inductance, and the remaining information such as core permeability, the
number of turns for other inductances, will be computed.

Program avoids guessing who is the manufacturer. Who needs to know if you
have already grab-bagged the items.

From inductance/number-of-turns data you can guess the type of material,
ferrite or iron powder, if you are interested.

Download program TOROID in a few seconds and run immediately.
---
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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