DIY 600:600

Kit · Jul 9, 2006

How hard is it?

Can it be done on iron powder toroids, or do you really need the laminations to make it work?

Im looking for OK specs, not super flat.

Trying to save :roll: some money and i dont mind the work.

Inductive experts, help me out.

alk509 · Jul 9, 2006

I doubt you'll save any money compared to just buying an Edcor...

Peace,
Al.

Kit · Jul 9, 2006

Sorry, no Edcor´s over here, i think.

I was only half serious about saving money, I was thinkin it would make a fun summer project to try and wind some wire.
Havent done much of that.

12afael · Jul 9, 2006

I build four for the PRR vari-mu.
they are not tested yet ,I hope finish it this week.
I use the small iron that I can find .
it give me 20hz and 30KHz but just with the scope and the signal generator , not the ideal test impedance.

penquista · Jul 10, 2006

Edcor sends transformers to germany, so why not to sweden. payment is easy using paypal. my last order took about ten days to arrive. just contact them, i'd recommend you to send them a mail and call them later to verify your order.

Kit · Jul 10, 2006

they are not tested yet ,I hope finish it this week.

Cool, let me/us know how they turn out.

I use the small iron that I can find.

What kind of core did you use?

BTW, i found this:
http://www.gormanmachine.com/videos/900m/900m.htm

alk509 · Jul 10, 2006

That's the coolest video ever posted on the internet!!! Those guys are about a half hour from my place, too! Maybe I'll arrange for a visit...

I don't want to know how much that winder goes for, though...

Peace,
Al.

12afael · Jul 10, 2006

What kind of core did you use?

here in chile you can`t find audio grade core. so I use the power transformer kind(EI). they are 3x3,5 cm is the smallest that I can find.

I didn`t use interleaving for this small transformer . I`m not sure if was PRR who say here in the forum that 600:600 are a lot more easy that build a 1:7 .

I use a xls that I post here to calculate turns .
http://www.groupdiy.com/forum/posting.php?mode=reply&t=9892

12afael · Jul 21, 2006

that is the frecuency responce of the vari mu. it still is not complete yet and I think it need a lot of work , just look that low frecuency loss, is horrible.

in my defense, they are my first transformers

Kit · Jul 21, 2006

Do you think the core is to blame for the LF roll off?

Still, good work. :thumb:

gyraf · Jul 21, 2006

Yep - too low A(L)-value core, or too few windings - both contributing to too-low primary inductance.

But the slight high-end drop points towards the stray capacitance and/or the leak inductance is sneaking in, so more turns on the windings is probably not the way to go from here.

Which leaves the option of using a core with higher A(L) - inductance per turn squared.

Jakob E.

solder_city · Jul 21, 2006

cant say if the trans is good or bad without knowing the impedance youre using to drive, and load impedance. even an otherwise very good transfo can show a bad low freq rolloff like that if the source imp is too high. whats the application of this transfo?

gyraf · Jul 21, 2006

that is the frecuency responce of the vari mu

12afael · Jul 21, 2006

here are my design sheet, seems to be good.

I use 1000 turns I have room for maybe 2000 turns, the core seems to be big enough , I have some more big cores to try but first I will put more turns I think .
the resistance of the coils are 80ohms, using .12mm awg37 wire.

Low level transformer design
from RadioDesigners Handbook xls by Rafael Castillo (12afael)

INPUTS value dimension variable
primary impedance= 600 ohms R see notes
secundary impedance= 600 ohms
input power= 0,063 watt W
permeability 10000 u
bass frec 1db loss= 15 herz
distortion at that frecuency= 20 percent
length of the magnetic path= 10,9 cm L
cross section area= 0,95 cm A
Returns
turn relation= 1 -
plus minus dB= 0,00 dB
primary inductance= 12,73 henry Lo
turns= 1076,8 turns N

sec voltage= 6,148 Volts E
flux density= 1455,48 lines per sq inch B
225,60 Gauss

But the slight high-end drop points towards the stray capacitance and/or the leak inductance is sneaking in, so more turns on the windings is probably not the way to go from here.

Maybe I need some interleaving here.

solder_city · Jul 21, 2006

80 ohms is pushing it for a 600/600 transfo. try to keep it 60 ohms or less. try a core with higher a-l value but watch out for saturation.

AnalogPackrat · Jul 21, 2006

Not to toot my own horn too loudly, but here is a thread with photos of my first DIY transformer winding project. I made another just like it and they both live in my 312ish preamps.

A P

Kit · Jul 21, 2006

Maybe you could try something like this:

http://www.groupdiy.com/index.php?topic=10441&highlight=zero+field

Very interesting..........zero field, current mode.........I did not know this.

CJ · Jul 21, 2006

Those UTC 600:600 on evil bay are so cheap.

You can wind your own, but the mechanical is a pain.
Shielding, core brackets, hookup leads, I mean for my 20 bucks, and hours saved, UTC.
Unless of course, you are in it for the DIY aspect, which I happen to think is tottaly cool.

12afael · Jul 22, 2006

80 ohms is pushing it for a 600/600 transfo. try to keep it 60 ohms or less. try a core with higher a-l value but watch out for saturation.

the high resitance could be the problem.

Kit , that look like an interesting trick but I want to learn as build my own good transformers.

I´m doing some simulations, with ltspice . I need some help with the impedances that look the transformer .
the input transformer look the input impedance(10k???) and 6.6k on the secondary ?
the interestage see a 44k//1k and on the secondary some megaohms.
is that correct?

is posible to make a bode plot with ltspice?

DIY 600:600

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