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Old 3rd June 2011, 10:17 PM   #1101
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I have been running my B1 all week now and am very happy with the sound with 5w 10ohm wirewound hot-rod resistors.

I have just added a couple of spare 5w 10ohm resistors in parallel to the 10ohm ones already fitted and have been using the buffer for the last hour with no noticable increase in temperature. I may try some 1ohm wirewound resistors next.

Brad
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Old 3rd June 2011, 10:19 PM   #1102
Salas is online now Salas  Greece
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Do you check the voltage drop across those resistors confirming the current goes up by Vacross/Rvalue ?
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Old 3rd June 2011, 11:56 PM   #1103
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Hi Salas,

only briefly, measured .1v which I thought must have been incorrect as I dont think that I got the DMM probes to connect properly and my DMM needs a new battery. I have now been running the B1 for a few housr and think that I can feel a slight increase in the temp on the outside of the case. Still sounds great as well.

will probably get 3.3ohm and 1 ohm wirewounds to try out at some point in the next few weeks and remove the boards from the case, so that I can fit the resistors properly.

Brad
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Old 3rd June 2011, 11:57 PM   #1104
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Hi salas,

out of interest is there a situation where 5ohm resistors will produce a lower running current in the B1

Brad
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Old 4th June 2011, 12:18 AM   #1105
Salas is online now Salas  Greece
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No. The lower the value of resistors the higher the current. You should get 1.5-2.2V across those current setting resistors.
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Old 4th June 2011, 09:13 AM   #1106
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by Builder Brad View Post
out of interest is there a situation where 5ohm resistors will produce a lower running current in the B1
yes.
when the Vdrop from DC supply to Vout drops below ~7V then the CCS becomes less and less capable of maintaining constant current.

The [/i]MINIMUM[/i] Vdrop in worst case conditions shoulde exceed 7V. That normally requires the operational Vdrop to be ~10V when mains voltage is "normal".
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regards Andrew T.
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Old 9th June 2011, 11:25 AM   #1107
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Hi,

This thread is too long to search for, maybe someone ask before, sorry first, my question is about the led direction, I haven't receive the on going DCB1 pcb group buy just investigate the picture from website, I found the led symbol as attached pic on pcb but I never seen before, which side is the + and - , thanks.

Click the image to open in full size.

Last edited by linhoffan; 9th June 2011 at 11:27 AM.
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Old 9th June 2011, 11:56 AM   #1108
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flat - cathode
round + anode
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Old 9th June 2011, 12:52 PM   #1109
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many thanks John
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Old 9th June 2011, 12:59 PM   #1110
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Quote:
Originally Posted by johnwmclean View Post
flat - cathode
round + anode
And to further clarify:

The anode (+) is the longer lead, with the rounded pictograph.
The cathode (-) is the shorter lead, with the flat back pictograph.

You should be able to verify this with a battery and a resistor (in series! to limit current) and be able to match the batches (either 3 or 5) of diodes for each half in voltage.

Anand.
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