Bo Hansen DI layout

[[silent:arts]]

Is CDIL a known brand, or no name? Their BC550 / BC560 work just fine in my V672X.

 

[Whoops]

besides big retailers like Farnel, Mouser and Digikey, local electronic stores or small shops don't really describe the brand of transistors, they just organize it by part number.
Being the markings on the transistors so small sometimes it's hard or impossible to know the original brand of what you're buying.

 

[Bo Hansen]

Whoops,

A little comment regarding that I always nag that you should only buy well-known and good transistor brands.

Of course there are some unmarked small signal transistor types that are perfectly ok, but today there are lots of fake transistors from China on the market.
It is usually absolute and difficult to get hold of types that are often fake.

Many times it is companies that sell spare parts for consumer electronics that buy these transistors as they do not get original types anymore, and of course there are lots to buy on eBay and similar internet markets.

I can take some of my own examples of poor experience of this.

Many of you probably think that I only deal with this DI box, but I design and build a lot of custom audio equipment with discrete transistor electronics such as microphones, preamps, equalizer and much more, so I buy a lot of BJT and JFET transistors for this reason.

I usually buy my favorite transistors in a thousand quantities because I select them in many different groups to be used for different purposes.
Fake types I have received instead of ordered originals are for example BC560C, 2SA970 and 2SJ74.
These was basically useless regarding max voltage, gain, NF and fT which is something completely different than it should be. 
Unfortunately, the appearance and logo can also be fake, as it should look like the original brand.

Sometimes it feels like some China sellers have a large bag with unmarked TO92 NPN and PNP where the transistor contains a universal "DIE" and where they then stamp the transistor type and brand that the customer wants.

So once again, be sure to buy well-known brands whether they are small signal or power transistors.

—Bo

 

[Whoops]

I know what you're saying and completely agree.

I was just saying that small local stores don't tell you the brand of the transistors they are selling, although they might be from a good or well known brand. I trust my local stores as the stock they have is NOS,it was stock ordered long before the Chinese fake transistors invading the market
Even Banzai that is an online store doesn't show you the brand of the transistors they're selling, and I buy there for many years and the products have always a good quality.
So yes, a lot of stores don't tell you the brand, they just don't find it's relevant

And sometimes by the marking in the transistor you might also have no information about the brand.

Farnel, Digikey and Mouser tell you the brand.
Ebay trasistors is something I avoid as it's full of fakes.

You can have a rough idea if a transistor is fake or not by measuring it, normally fake chinese have a lower hfe, and for a C type you should be expecting and HFE above 420. Even then it's just a rough way. As nothing guarantees 100% that a fake will not have an higher hfe value

 

[FarisElek]

Want to thank you for this project, Bo! I'm working with some friends I've known since childhood covering random rock songs we loved (and still love) for fun during this pandemic to pass time. We're over a 1000 miles from each other so everyone is recording remotely. My friend's bass sounded so nasally the first time we did it that I built one of these DI's and send it to him for our next cover (Moody Blues - Ride my see-saw). So much easier to mix his bass and it's a great gift idea for a musician.

Stay well,
Ryan

 

[Bo Hansen]

Thank you Ryan, very nice to hear that you like my DI-box design, and that you managed to get the bass sound when you do long distance tracking.

Btw, you mention the Moody Blues.
In 1973, AUDEX from Gothenburg Sweden, an amplifier factory I was part of, delivered two modified Audex TR102 amplifiers to Mike Pander, which he used for his Mellotron under his Europe tour during this time.

--Bo

 

[FarisElek]

Thank you Ryan, very nice to hear that you like my DI-box design, and that you managed to get the bass sound when you do long distance tracking.

Btw, you mention the Moody Blues.
In 1973, AUDEX from Gothenburg Sweden, an amplifier factory I was part of, delivered two modified Audex TR100 amplifiers to Mike Pander, which he used for his Mellotron under his Europe tour during this time.

--Bo

That's amazing. Those appear hard to come by these days.

 

[Bo Hansen]

Ryan,

If you mean the Audex amp, TR102 A or B are often sold second-hand on the Swedish market, we manufactured several thousand of them.

It was available in A normal instrument or B Bass version, 100 watt in 4 or 8 ohms version.
The 4 band equalizer was Audex's special feature, a completely own design, no "tonestack or Baxandall" but a smart solution well adapted to musical instruments.

This is a powerful and clean solid-state amp, a reliable workhorse.

--Bo

 

[Bo Hansen]

Have you seen this fantastic creation that includes our DI-Box circuit board.

Here is a link to a Facebook post about this iron DI-Box:
https://m.facebook.com/groups/517919938413134?view=permalink&id=1385851958286590&fs=2&focus_composer=0

--Bo

 

[Whoops]

That looks brilliant

 

[Ricardus]

Should we tell him? 

 

[Bill2000]

Hi I am looking for either the gerber files or a place where I can purchase the PCBs from. I live in Australia so the Gerber files might be the better way to go so I can get the PCB's made locally
Regards
Bill2000

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

 

[Bo Hansen]

Bill2000,

This circuit board has been available in two versions, the first version was made by a forum member in Denmark who also distributed and sold this PCB, but from 2015 we made an updated PCB layout that Volker Meyer/51xAudio in Berlin took over manufacturing and distribution/sales.

The original Gerber files for these PCB layouts belong to the one who has paid for PCB manufacturing and arranges the distribution of these PCBs all over the world, so I can not publish this Gerber file on my help page for this DIY DI-Box.  www.hansenaudio.se/techpage.htm

But there are good pictures of both versions on my help page, so if you want to make your own circuit boards, you can use these as a model for your own circuit board layout.

I do not know if you intend to make circuit boards only for your own use or or in larger numbers to resell.
Please read the rules for using my DI-Box design which can be find at the top of my help page for this DI-Box.

--Bo

 

[Whoops]

Hi I am looking for either the gerber files or a place where I can purchase the PCBs from.

The first post in this thread, actually the one you quoted in your post it's pretty clear where you can buy the PCBs from...

 

[thewotan]

Hi there!

Newbie here, this is my first post. I'm having some trouble making this DI to work, I'm reading through the whole thread hoping to learn more, but it's pretty long so I thought that I'd go ahead and ask while I read the thread.

So, I'm not the best at soldering, but I've been soldering cables and patchbays for some time now. I tried to put this DI together but it is not working. Some things that might be worth commenting:

- First of all, I don't have the card in the box nor the output jack connected (I take it should work without it?). I have the ground lug connected with a clamp to the enclosure.

- When I turn phantom on, the LED lights bright for a couple of seconds and then it faints until is barely visible.

- Measuring between the input jack ground and LED is reading 48.5 V. The other reading between input jack ground and the junction of 3,9k resistor, 10uF capacitor positive end and emitter on BC560 transistor reads 46.6 V

- I have checked for continuity and it seems correct (no shorts). I did find a short between pin 2 and 3 of the XLR out. At first, I thought that it may be a solder bridge, but I resoldered it with extra care to make sure there was no solder bridge. But it is still shorted. Is this normal? For what I understand in the schematic, it is, but it seems counterintuitive to me...


Anyway, there's no sound coming out of it (no hiss, noise, nothing) and I'm totally clueless. Do you have any idea that can help me to troubleshoot it?

Also, I wanted to thank you guys for all the amazing information you have in here. I understand 5% of what you are talking about, but a lot of fun nonetheless!!

 

[Ricardus]

How about uploading some hi-res pics of the component side of the board and the solder side of the board?

 

[Whoops]

I did find a short between pin 2 and 3 of the XLR out. At first, I thought that it may be a solder bridge, but I resoldered it with extra care to make sure there was no solder bridge. But it is still shorted. Is this normal? For what I understand in the schematic, it is, but it seems counterintuitive to me...

1) PIN 2 and PIN3 of the output XLR are both connected to the same coil of the transformer so there will be a small DC resistance there that your DMM might beep as a short, it's just a couple of ohms.
Measure DC resistance between PIN2 and PIN3, for this example let's consider a "short" a measurement under 1ohm, something almost zero. How much do you measure? I'm sure it's more than that and that is just the transformer coil.

2) Print the schematic and have an highlight marker. check all components one by one and highlight each one checked in the schemati.
Check all resitor values, sometimes it's easier to use an 47K resistor instead of 47R or vice verse.
Check all capacitor values
Check all electrolytic caps orientation
Check all Zenners and diodes orientation
Check all transistor orientation
Inspect PCB traces for solder joints
Recheck all wiring

3) do like Ricardus suggested, post pictures of component side and traces of the PCB

How about uploading some hi-res pics of the component side of the board and the solder side of the board?

 

[Bo Hansen]

thewotan,

You can test drive the DI-box card without the metal box, but use all connectors with their respective cables so that they reach the right place on the circuit board.

When measuring all test voltages, use XLR pin-1 or sleve/ground and input or output tele-jacks as minus/black test-pin for your votage meter.

You say that the LED lights up for a short while and then goes out shortly after you turn on the phantom power.
This indicates that the DI-box electronics do not draw any current, which should normally be 3.5 mA when working properly.
The reason why the LED lights up for a short while and then fades out is that it only charges the 100uF electrolyte capacitor every time you turn on the phantom power.

Go to my help page for this DI-box www.hansenaudio.se/techpage.htm and at the end under the heading "final testing" there are all the important voltage test points you need for troubleshooting.

The first thing you should do is as the other guys said here before, check that you have chosen the right value for all resistors and that they are in the right place, and of course also all capacitors and diodes.
Check that the transistors are turned correctly and that the NPN BC550C is the first upper transistor and PNP BC560C as the  lower at the 3.9k resistor.

It is really only one voltage test point that you need to measure, if this is correct, the electronics will work as they should.  Measure on BC560C emitter where 3.9k and 10uF positive end meet, where you should be able to measure around 12 volts dc.

If this voltage is there, then the active electronics work, if you still have no sound, the problem can be incorrectly connected telejacks or a broken transformer.
NOTE, never cut the pins on the Lundahl transformer after soldering.

--Bo

 

[thewotan]

First of all, thanks to everybody for your comments!

I checked all the components with the multimeter and seemed OK, so after that I rechecked the board for any bad soldering and found a couple of spots that seemed strange, so I tried to resolder only to find that the pad from the PCB was gone :-\ 


I had my iron at around 300º (or that was my cheap soldering station marked...). Was that too hot and that was what caused the pads to go away?

Anyway, I had another PCB and tried to built it from scratch and kid you not, it works!! Was the best feeling of 2020!! ;D ;D

I did the recommend test and measured 25'5 V between the input ground and  the 6,8k resistors and the LED, which is above the parameter of 24 V +-1 V. Why could this be?

The test between input jack ground and the juntcion of the BC560 and condenser and resistor reads 11'6 V, which is between the parameters.

Afterwards I plugged my bass and there it was! No noise at all and clean signal! I've been reading about your project for so long and finally hearing it was amazing  ;D ;D  So thank you very much, Bo and everybody involved in this project!

Now, I'm debating myself if enter the rabbit hole and order some Lundahl and Haufe to see if the difference is worth it, but right now, the OEP sounds very good!

 

[Bo Hansen]

thewotan,

Nice to hear that you succeeded with the DI-box in the end, and good luck with your next builds with alternative transformers.

--Bo