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Old 21st August 2006, 07:28 AM   #1
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Default Building DDDAC questions?

I was going to e-mail Deode but he's on vacation. I had three questions.
-I was wondering if it mattered what gauge wire I ran from the positive and negative terminals to posititive and negative of DDDac.
- In the DAC kit there wasn't a 120 Ohm resistor included. A single 130 Ohm was included so I am guessing this was a mistake but just wanted to make sure there wasn't a design change for any reason.
- Before I put the coils in he said to test the voltage. Should I have the chips in and everything else on the board on when I test the coils or can the Dac chips not be installed yet? Should this be done on every board. I will take them out and test on my USB board because didn't say to do that on there.
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Old 22nd August 2006, 10:54 PM   #2
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Anybody got some help?
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Old 23rd August 2006, 12:11 PM   #3
Z1 is offline Z1  Italy
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Hi suspencefull, excuse me in advance for my bad english...

-I was wondering if it mattered what gauge wire I ran from the positive and negative terminals to posititive and negative of DDDac.

I don't think that is a problem, if the cable isn't too much long. I'm using a 14AWG cable with no problems from about three months.

- In the DAC kit there wasn't a 120 Ohm resistor included. A single 130 Ohm was included so I am guessing this was a mistake but just wanted to make sure there wasn't a design change for any reason.

If You have the 12dac tower the correct value is about 120 Ohm (130 will work, Doede suggest to fine tune this value) there is no change on the project and for me 120 ohm is fine.

- Before I put the coils in he said to test the voltage. Should I have the chips in and everything else on the board on when I test the coils or can the Dac chips not be installed yet? Should this be done on every board. I will take them out and test on my USB board because didn't say to do that on there.

I have mounted all the components on the two boards except the coils before test it and all worked at the first attempt

Good work!
Fabio
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Old 24th August 2006, 09:59 PM   #4
pburke is offline pburke  Germany
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Location: Madison Wisconsin
Default Re: Building DDDAC questions?

Quote:
Originally posted by suspencefull
I was going to e-mail Deode but he's on vacation. I had three questions.
-I was wondering if it mattered what gauge wire I ran from the positive and negative terminals to posititive and negative of DDDac.
- In the DAC kit there wasn't a 120 Ohm resistor included. A single 130 Ohm was included so I am guessing this was a mistake but just wanted to make sure there wasn't a design change for any reason.
- Before I put the coils in he said to test the voltage. Should I have the chips in and everything else on the board on when I test the coils or can the Dac chips not be installed yet? Should this be done on every board. I will take them out and test on my USB board because didn't say to do that on there.

wire should handle enough current for the number of DACs you are using. a 24 chip DDDAC pulls about 2amp constant, a 60 chip will need a wire that can handle constant 5amps

not sure about the resistor - measure it, put it in, see what happens. Depending on where it goes, it may not matter.

you are supposed to measure the voltage before connecting a final wire to protect those chips already on the USB board. If you mess up anywhere the chips could fail with overvoltage. I think the instructions on his web site are quite clear on that.

Don't make any mistakes with the components, measure twice, and connect the final lead to the ICs once you see proper voltages where indicated on the PCBs
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Old 25th August 2006, 07:15 AM   #5
dddac is offline dddac  Germany
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Join Date: Jul 2003
Location: Wiesbaden
Default Re: Building DDDAC questions?

Quote:
Originally posted by suspencefull
I was going to e-mail Deode but he's on vacation. I had three questions.
-I was wondering if it mattered what gauge wire I ran from the positive and negative terminals to posititive and negative of DDDac.
- In the DAC kit there wasn't a 120 Ohm resistor included. A single 130 Ohm was included so I am guessing this was a mistake but just wanted to make sure there wasn't a design change for any reason.
- Before I put the coils in he said to test the voltage. Should I have the chips in and everything else on the board on when I test the coils or can the Dac chips not be installed yet? Should this be done on every board. I will take them out and test on my USB board because didn't say to do that on there.

Back on email (relocating homes is not easy without ail )

any way, here are my answers:

-I was wondering if it mattered what gauge wire I ran from the positive and negative terminals to posititive and negative of DDDac.

use quality cables please minimum 2,5 mm2 or so. I use good speaker cable, silver coated

- In the DAC kit there wasn't a 120 Ohm resistor included. A single 130 Ohm was included so I am guessing this was a mistake but just wanted to make sure there wasn't a design change for any reason.

should be 120, what is the color code ?????


- Before I put the coils in he said to test the voltage. Should I have the chips in and everything else on the board on when I test the coils or can the Dac chips not be installed yet? Should this be done on every board. I will take them out and test on my USB board because didn't say to do that on there

As long as the coils are not in, it does not matter if the chips are in, as they are not connected..... so no need to take them out ...

it is no big thing, but a small step to avoid killing the chips, if something was done wrongly with the power supply...
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Old 25th August 2006, 08:09 AM   #6
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Thanks for the help. I see not 3.3V, but 5V on the USB board (I don't have it connected to the dac board yet. I was going to get it working first.) I disconnected the coils and measured. Does anyone have any values at what the transistor's should output and what should be across the resistors so I can see where the voltage is messed up. Thanks a lot.
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