[Soeren_DK]

Bo Hansen's DI page:
http://www.hansenaudio.se/techpage.htm#active%20DI-box,%20my%20work%20horse%20from%201975
and the schematic is here: http://www.hansenaudio.se/Active%20DI%20box%201975.jpg

Boards available here:
From June 2015, Volker is the new supplier of PCBs.
https://groupdiy.com/index.php?topic=39570.msg488632#msg488632

Shopping list:
US: http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=12eddc2712
http://benlindell.com/diy/Bo-Hansen-DI-BOM.pdf (made by benlindell)

EU: http://www.mentol.dk/diy/bohansen/BOM - Diyfanatic - bo DI.xlsx (made by diyfanatic)

Help:
TRANSISTOR CHOICE
HAUFE TRAFO BUY
MAKING PAD MOD


Self-etching papers:
http://www.mentol.dk/diy/bohansen/bohansen.pdf
http://www.mentol.dk/diy/bohansen/silkscreen.pdf

Cheers
Soren

[Soeren_DK]

The behind

[zebra50]

Nice idea!

How hard would it be to make this accept alternative transformers? For example a Sowter as noted on Bo's web page, or an OEP like on the Gyraf G9?

[rotation]

Nice idea!

How hard would it be to make this accept alternative transformers? For example a Sowter as noted on Bo's web page, or an OEP like on the Gyraf G9?

This was my first thought when i've seen the layout. Another good thing to do would be making layout a little smaller. That wouldn't be hard if he will do rerouting to accept other transformers.

Miha

[Soeren_DK]

Nice idea!

How hard would it be to make this accept alternative transformers? For example a Sowter as noted on Bo's web page, or an OEP like on the Gyraf G9?

I have looked on the Sowter but I can't figure out the right spacing dimension.
http://www.sowter.co.uk/specs/3678.htm

These dimension dosen't fit any standards. As opposed to Lundahl http://www.lundahl.se/pdfs/datash/1538_8xl.pdf

Cheers
Soren

[stitch-o]

Id love to make a rack of 4 of these!

[Davo]

Nice one Soeren!!  My favorite DI

[mitsos]

Very good idea! What size is the PCB?   Also think other trafo options would be good... maybe a cinemag footprint... that would give the choice of Cinemag, Jensen and Altran trafos, including the EA2622, though I don't know how any of these would work in the circuit... Is 1:5 the ideal ratio here?
cheers!

[Soeren_DK]

The board is 80 x 50mm so 4 of them will fit a EURO card. Do you have some info about the cinemag footprint?
I don't have knowledge to tell if the 1:5 ratio is ideal or not.

Cheers
Soren
 

[Bo Hansen]

Sören,

I send you a e-mail 2009-11-16 about the OEP pc-board alternative, have you seen that ??

Please, before you done modifications on the PC-bord, and spread it out for DIY, ask me, so I can check it out first, I will be glad to do that for you.

When you change transformer, it is very important that the impedance, ratio and phase configuration will be right.

Note, that the Lundahl LL-1538 is optimized for best headroom when you load the DI-box XLR output around 1 - 2 kohm.
Maybee with other transformers, the  3,9k resistor must be change for same result.

--Bo

[mitsos]

It may not be the ratio, but look at the CM75101 as that also has dual primaries (secondaries in this case, since it is reversed), and is the same footprint as the EA2622 and some Altrans and smaller Jensens. While you're at it, not to give you too many headaches, but maybe a jumper to choose series/parallel primaries (secondaries here) might also make it more universally accepting of PC mount trafos, although, in the end, people could just use leaded ones and hook them up any way they want. 

The OEP is also a good inexpensive option and I believe all three footprints can be made to work together if you're into puzzles.

@Bo, can you explain the bit about the 3K9 resistor? Is that biasing the transistor?

[Soeren_DK]

I send you a e-mail 2009-11-16 about the OEP pc-board alternative, have you seen that ??

I haven't received that mail. The latest mail from you is the one from October 28.

Please, before you done modifications on the PC-bord, and spread it out for DIY, ask me, so I can check it out first, I will be glad to do that for you.

Of couse. I wouldn't put your name on anything you haven't seen, checked and approved first.

Cheers
Soren

[Bo Hansen]

Sören,

It was on this gmail address you have sent to me before, have you change adress ?? PM or e-mail me, and i will send you a copy.

Mitsos,

The 3,9 kohm resistor are the emitter resistor for the last PNP emitter follower transistor, and it will set the current trough this transistor, and also the total current draw from the phantom power feed.

So you must choose a good compromise between highest internal B+ voltage and the transformer feed capacity.

In the Lundahl LL-1538 case it was approx. 3,5mA total, and I also get 24 volt as B+, and this is a nice compromice.

--Bo

[Soeren_DK]

It was on this gmail address you have sent to me before, have you change adress ?? PM or e-mail me, and i will send you a copy.

You got mail

Cheers
Soren

[[silent:arts]]

nice. I will toss away my layout I started
to confuse a little more, there is a nice Haufe transformer, designed to replace the LL1538 ...
we will use it as an option in the JensAmp, since (even it is Haufe) the price is much lower

Soren, if you are interested in adding this footprint (very easy) I will send you some details

[Bo Hansen]

Silent:arts,

Very Interesting, both Haufe and Pikatron have done nice transformer since long time ago.

Please can you PM or email me information about this LL1538 replacemaent from Haufe. (or maybee in a repaly here on the forum)

--Bo

[Soeren_DK]

@Bo
Great, will you look at the info from Silent and send me some info about it afterwards.

What drill size is common used for resistors, diodes etc.. I have used the same size for all holes (0,80mm) except the "input", "amps out" "ground", XLR out (1,00mm) and the trafo (1,50mm)

Cheers
Soren

[[silent:arts]]

Bo, mailed you. the datasheet is german only, let me know if you need more information or a sample.

Soren, 0,8mm is fine for resistors (<1W), for 1N4XXX Diodes (DO41) I use 1mm.
the transformers holes are very different, you have to refer to the datasheets.

[rotation]

nice. I will toss away my layout I started
to confuse a little more, there is a nice Haufe transformer, designed to replace the LL1538 ...
we will use it as an option in the JensAmp, since (even it is Haufe) the price is much lower

Soren, if you are interested in adding this footprint (very easy) I will send you some details

Can you tell us more about this transformer? Can we buy it or it was only a batch for certain people?

Miha

[detonator]

Can you tell us more about this transformer? Can we buy it or it was only a batch for certain people?

please check http://www.lundahl.se/

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