DI from DIY Factory

[Nikolay]

Hi guys. I make a small PCB for this project:
http://www.diyfactory.com/projects/countryhick/countryhick.htm


sch and pcb are here:
http://files-upload.com/394094/di.pdf.html

I will make this DI box soon and post some pictures.

 

[BYacey]

You can eliminate the R12 / 10K resistor, this was added for simulation only.
Looks good!

 

[12afael]

great job Nikolay, C2 should be a film cap like on hamptone Dibox.

 

[BYacey]

Countryman used an electrolytic for the transformer coupling cap, but a film should work just as well; probably better long term. I'm still using a 20 year old Countryman and it doesn't seem to have degraded in any noticeable manner. The cap isn't worked too hard, and because they seal it in epoxy, the chance of it drying up is probably reduced considerably. It is however important to use a tantalum for C2, any leakage here will throw the bias voltage off due to the high impedance involved.

 

[Nikolay]

Ok guys, I'm on the way to make better PCB with thru input and Wima 10u capacitor. I will post the new sch and pcb soon

 

[Nikolay]

A new version 1.3


http://files-upload.com/400441/dibox.pdf.html

 

[BYacey]

The clone is the type 85 as shown.

 

[12afael]

Nikolay your last link don`t work.

 

[Nikolay]

^ Just wait 30 seconds to show the download link.

 

[Bluzzi]

Nikolay - great job, thanks.

Just noticed 2 things though.

C2 does not have polarity showing anymore. Which one is correct?

Also R12 is now accross secondary of T1. It was accross the primary before. Which one is correct?

jim

 

[Samuel Groner]

C2 does not have polarity showing anymore.

Read above and look at the footprint. It's a film capacitor now.

Also R12 is now accross secondary of T1. It was accross the primary before. Which one is correct?

Neither. R12 is unnecessary (as has been pointed out before) and can/should be omitted. Alternatively a carefully selected RC zobel nework may be used at the secondary to flatten the frequency response if desired.

Samuel

 

[Bluzzi]

Thanks, got it (I don't re-read every message everytime a new is added). I'll update my DWG to elliminate future confusion. Might be a good idea to do that to original for others.

jim

 

[BYacey]

There might be some confusion arising C2 being a film or tantalum. On my original schematic C2 is indeed a tantalum, but on Nikolai's scematic the designation number has been changed to C1. C2 could definitely benefit somewhat by using a film cap here, and C1 in this case being a tantalum.

Which direction is up now? I'm confused :grin: :grin:

 

[Nikolay]

^ There is no matter witch of capacitor type can be used. C2 (in the original sch) is used to create a virtual ground with 2x 2.5Meg.
You can use also 10u too.

 

[BYacey]

Keep in mind that any small leakage current through that cap will lower the bias voltage at the virtual AC ground and on the gate of the FET. I believe this is why they chose a tantalum for that purpose.

 

[12afael]

^ Just wait 30 seconds to show the download link.

Not Found

The requested URL /es/400441/dibox.pdf.html was not found on this server.

:?:

 

[Ptownkid]

you should see a counter counting down for 30 seconds, and then the link is there.

 

[12afael]

mmm I have troubles with firefox and explorer, on both I have the 404 error.
my IP is low quality ??? :? not luck with a phpproxy...

can someone email me the file?
incupicioso (at) hotmail.com

Rafael

 

[Nikolay]

I make ver 1.5 - maybe the latest version. I will make PCB tomorrow.
Here are pdf to download:
http://www.mediafire.com/?7co4wxbzcx2
If there is some problems I upload the file here too:
http://naudio.hit.bg/di/di.pdf

D5, R12, R13 and C5 are smd:

D5- SMA
R12 and R13 - 0805
C5 - 1206

Good luck

Pictures and BOM will be soon

I have one question: Can I use BC550 instead 2N4401 ?
Also BC550 is better for audio and I used offen.

 

[Samuel Groner]

Can I use BC550 instead 2N4401?

I was about to suggest that--I'd use BC550 in this place, though make sure to get the C rating and to change the pinout as it is not the same.

Also BC550 is better for audio and I used offen.

Well, what is "better"? BC550C has much higher hFE (which is helpful here), but 2N4401 got much lower voltage noise (which doesn't matter for this application).

R12 still needs elimination...

Samuel