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-   -   Salas DCG3 preamp (line & headphone) (https://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone.html)

zman01 19th January 2017 02:49 PM

Power transformer blues?
 
Got these nice potted transformers - 50V, 2 x 18V

http://sg.element14.com/multicomp/mc...18v/dp/9531793

Tested the transformers without load - getting 19.45 VAC from input mains of 220 Volts. The input mains voltage goes up a bit at times to ~225 volts.

I see lot of the recent discussion on builds with lower voltage transformers... my trafos are ok for the build? I have also ordered the DCSTB power supply board.

Also saw that Tea-Bag is using 17V transformers in his build:

http://www.diyaudio.com/forums/blogs...er-supply.html

Look forward to guidance from Salas and other builders. :)

Salas 19th January 2017 03:57 PM

"Extremely low radiated magnetic field, suitable for sensitive electronics"

That's positive

When off-load most transformers give bit more AC which is normal. No worries your transformers are fully compatible to this build and also look very good for construction and electrical spec.

zman01 19th January 2017 04:44 PM

Thank you for Salas! :)

ammel68 19th January 2017 05:12 PM

Diode Connections.
 
1 Attachment(s)
Salas, thank you for answering my questions in post 1117.:)

Reason I was asking about using PF5102s with higher than 8mA Idss is because I have quite a few matched pairs over 8mA.
Would the 33 ohm resistors have to be changed to use them?

Also, would someone please look at my diode connections below to see if they are correct?
I always seem to get those darn things connected wrong.:o

Salas 19th January 2017 05:24 PM

Are you making a DCSTB copy for your DCG3 or one to set differently for powering a different project?

If you want to keep about 5mA ref current make them something like 100 Ohm or more

Look at DCSTB board's photo in post#2 for bridge diodes orientations

Marra 19th January 2017 05:38 PM

Quote:

Originally Posted by zman01 (https://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone-post4957238.html#post4957238)
Got these nice potted transformers - 50V, 2 x 18V

http://sg.element14.com/multicomp/mc...18v/dp/9531793

Tested the transformers without load - getting 19.45 VAC from input mains of 220 Volts. The input mains voltage goes up a bit at times to ~225 volts.

I see lot of the recent discussion on builds with lower voltage transformers... my trafos are ok for the build? I have also ordered the DCSTB power supply board.

Also saw that Tea-Bag is using 17V transformers in his build:

http://www.diyaudio.com/forums/blogs...er-supply.html

Look forward to guidance from Salas and other builders. :)

The Multicomp transformers are what I have used in my build. Good quality and very quiet in use with this build.

ammel68 19th January 2017 06:00 PM

Quote:

Originally Posted by Salas (https://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone-post4957422.html#post4957422)
Are you making a DCSTB copy for your DCG3 or one to set differently for powering a different project?

Look at DCSTB board's photo in post#2 for bridge diodes orientations

Once I have boards made, I'll be using them for both the DCG3 and other preamps/buffers I build.

I've already looked at the photo in post 2. I'm trying to follow the board on the left.
I believe I've connected the same diodes with the top trace(blue in my photo) and lower trace as Tea, but I would like to make double sure before submitting any Gerbers.
Surely someone can verify if their correct. If not I can ask over in the PS forum.

Salas 19th January 2017 06:27 PM

Of course they are correct when two cathodes make a plus and two anodes make a minus in a bridge

Salas 19th January 2017 06:32 PM

Quote:

Originally Posted by Marra (https://www.diyaudio.com/forums/analog-line-level/296406-salas-dcg3-preamp-line-headphone-post4957436.html#post4957436)
The Multicomp transformers are what I have used in my build. Good quality and very quiet in use with this build.

Do you use it on the plank meanwhile before boxing it up?

Marra 19th January 2017 06:37 PM

They are yes.


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