Transformer DIY "1st try"

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nrgrecording

Well-known member
Joined
Jun 4, 2004
Messages
566
Location
Ger manley (germany) ;-)
Hey guys.

Today we did it. Yes, we wound our first homebrewed trannie. We used an old Siemens Telephone transformer for bobbin and core.

We decided to go with an 2:1 ratio with around 5 Henry primary inductance to use with jakobs SRPP tube output stage.
So we had to find out the AL value of the core. For this reason
we wound 11 turns of wire around the existing windings. The
resulting inductance for this 11 windings was 600µH.

AL= L/N² = (600µH/11²)
AL= 4958,7 nH

The required amount of turns for a 5 Henry input primary inductance is then calculated by:
Formel.jpg


N = 1004 turns

We decided to go with 2 primary sections, 500 turns each both
enclosing the secondary section (also 500 turns)

transformerDIY.jpg



Test winding for calculating AL value.
175-7579_IMG.jpg


No hacksaw needed at all.. only two screws to remove. :green:
175-7583_IMG.jpg


175-7585_IMG.jpg


The AUMANN atomic coil winder.
175-7587_IMG.jpg


Ready to go!
175-7586_IMG.jpg


175-7588_IMG.jpg


175-7593_IMG.jpg


Done.
176-7601_IMG.jpg



Measurements:
low frequency response is -3dB@4,7Hz with 50ohm source impedance,-3dB@22Hz with 600ohm source impendance
hi frequency response is flat up to 300 KHz, peaks around 5dB@436KHz
measurements with 10kOhm load


Not bad so far :green:
Damn, we have no SRPP stage around at the moment to do some listening tests. We will post our impressions later these days.

Steffen and Frank.
 
Wow... this is cool.

Question:
>we wound 11 turns of wire around the existing windings. The
resulting inductance for this 11 windings was 600µH.

How did you measure 600uH? I mean, what equipment did you use? Sorry for my ignorant question.
 
[quote author="owel"]Wow... this is cool.

Question:
>we wound 11 turns of wire around the existing windings. The
resulting inductance for this 11 windings was 600µH.

How did you measure 600uH? I mean, what equipment did you use? Sorry for my ignorant question.[/quote]

hi owel,

we used the inductance measurement function of a cheap multimeter:

multimeter.jpg


only 2% precision, but good enought for this task

steff
 
[quote author="Flatpicker"]Too Cool! :cool:

Where do you get a coil winder like that?[/quote]

Franks brain is directly connected to
ebayLogo.gif
 
Where do you get the wire from? Carnhill gave me the impression you had to buy it by the mountain.....

It's up there with Jakob's and IJR's engraving machines :shock:
 
Dang, You beat me too it!
But boy am I proud of you guys!
Men of my heart!


Now give me that winding machine!

What kind of insulation?
:guinness: :guinness: :guinness:
 
[quote author="Jonathan Hayward"]Where do you get the wire from? Carnhill gave me the impression you had to buy it by the mountain.....[/quote]
You can buy wire in small quantities from RS.

Best regards,

Mikkel C. Simonsen
 
[quote author="nrgrecording"]Hey guys.


Damn, we have no SRPP stage around at the moment to do some listening tests. We will post our impressions later these days.

Steffen and Frank.[/quote]




Can't wait for you to tell us how it sounds! :grin: :guinness:
 
[quote author="cjenrick"]Dang, You beat me too it!
But boy am I proud of you guys!
Men of my heart!


Now give me that winding machine!

What kind of insulation?
:guinness: :guinness: :guinness:[/quote]


hehe :) ....can´t wait to hold a working homemade 60K:600 tranni in our dirty hands ...and connect it to the anodes of 2 crappy old RCA tubes, workin´in parallel...hehe :-D

just some self-adhesive  foil between the sections. ...I think the capacitive coupling between pimary and secondary is the reason for the good HF response...no screen windings at all...it´s made for output, so we don´t care much about CMRR....

back to reading RDH.....

steff
 

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