One more time ... choke me !

a DIY, modified Mullard 5-20 monoblock design

One more time ... choke me !

Postby TomMcNally » Thu Mar 12, 2009 3:14 pm

OK ... I did a search on transformer orientation, and I must
admit I am "orthagonally" challenged ... I need a plain English
answer ...

Picture 1
Image


or Picture 2
Image


Thanks !!!!
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby nyazzip » Thu Mar 12, 2009 11:02 pm

for what its worth my reissue marshall guitar amp uses the choke/opt geometry in "picture 2", but the power transformer laminations occupy yet another plane, so its "x/y/z" if you will.
not exactly hi-fi, i know
<i>the poor craftsman blames his tools</i>
User avatar
nyazzip
KT88
 
Posts: 1073
Joined: Wed Jan 09, 2008 1:24 am

Postby EWBrown » Fri Mar 13, 2009 6:07 am

With these particular Hammond trannies and chokes, the center axis of the windings is in the same plane as the long axis of the labels on top.

In your first photo, there is magnetic coupling between the choke and the OPT and in the second, coupling betwen the power trannie and choke (which is a lesser problem). The leads on the choke could be swapped in order to buck the magnetic field from the power trannie.

Think of X axis as left and right, Y axis as front and back, and Z axis as up and down.


If you could lay the power trannie on its side, then picture 2 would be the ideal "XYZ" orientation.

The ideal situation is like an ST-70, that the axes of the windings of the power trannie, outputs and choke are all at mutually perpeidicular axes (X, Y, Z) . FWIW, the core orientation in most open freme trannies and chokes (like the C354) is vertical.

The best solution, if the chassis dimensions allow, would be to locate the power trannie and choke at one end of the chassis, the board in the center, and the output trannie at the other end. This allows more separation, and makes the wiring from the iron to the board more direct, with a cleaner under the chassis layout.

HTH

/ed B
Real Radios Glow in the Dark
User avatar
EWBrown
Insulator & Iron Magnate
 
Posts: 6389
Joined: Wed Mar 19, 2003 6:03 am
Location: Now located in Clay County, NC !

Postby TomMcNally » Fri Mar 13, 2009 7:53 am

Locating the power transformer and choke on one end and
the output transformer on the other may keep the chassis
from bending under the weight too. I hope to build these
tonight, just need to do the sheetmetal work and then
after using one of the circuit boards as a template, populate
it. It will be easier than the first one, since the Mouser
bags are now in resistor order !

Thanks
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Postby Geek » Fri Mar 13, 2009 9:03 pm

Is there room under the chassis to mount something?

Sometimes you can mount two chunks of iron with the same bolt pattern, one on top, one underneath at 90 degrees with the same four screws Yellow_Light_Colorz_PDT_11

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
User avatar
Geek
KT88
 
Posts: 3585
Joined: Sun Oct 21, 2007 3:01 am
Location: Chilliwack, British Columbia

Postby TomMcNally » Fri Mar 13, 2009 10:01 pm

Gregg -

I went with the 2" depth chassis, so no room underneath.

I mounted the power transformer and choke at the
back end, and the output transformer up front.
It will require routing the output leads around the
chassis from front to back, but it should be OK.

The first amp is done, I'll fire it up tomorrow, and
then build the second one. My tubes won't be in until
Monday, so I'll have to borrow some from another
amp for testing.

... tom
User avatar
TomMcNally
Darling du Jour
 
Posts: 2729
Joined: Sat Nov 19, 2005 2:19 pm
Location: Northfield, NJ

Ike for Pres

Postby msmpe » Wed Mar 25, 2009 12:17 am

Those Ikes make me drool :P you do really nice work Tom. Your work is definitely a standard to compare by and strive for. Thanks Ed for the orientation tips, I voted for #2, but [the odd] final orientation seems to be PDG!
8>) Mike

If there's no sound in a vacuum, where'd the music come from?
msmpe
KT88
 
Posts: 305
Joined: Wed Mar 26, 2008 12:31 pm
Location: central california coast


Return to eiclone

Who is online

Users browsing this forum: No registered users and 11 guests