Mezmerize DCB1 Building Thread - Page 5 - diyAudio
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Old 24th November 2010, 05:29 PM   #41
lpm76 is offline lpm76  Denmark
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Dont know if I was the only one who was slight confused about the different iterations of the board.

Anyways, the bom for 4.2 is here, and I think it is the right one.

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Old 26th November 2010, 09:12 PM   #42
Horio is offline Horio  United States
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Quote:
Originally Posted by Tea-Bag View Post
Second 100uf cap becomes small MKP type cap of .2 or .1uf, make sure it fits.

Tea-Bag, on the DCB1 Blue Hypno BOM, it says to use a film cap between 0.1uf and 10uf. How does the value of this capacitor influence the circuit? I found 0.1uf WIMA caps from Mouser with 5mm lead spacing.

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Old 26th November 2010, 10:00 PM   #43
Tea-Bag is offline Tea-Bag  United States
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Horio,
Let me correct myself first, it's the first cap that gets replaced, not the second.
Technically I am not positive what the differences are. Both are bypass caps for the IRFP Voltage Reference. The film cap seems to offer better sound. I would buy both and try both.
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Old 28th November 2010, 03:03 PM   #44
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Looks like the board is slowly getting populated.
Unfortunately I managed to get a bunch of 100 perfectly matched let at 1.84 V, there is no way of putting them together to make 9V.

I am using the method suggested by Salas for matching, using the jfet as a current source. For this I assume that the battery voltage should be greater than 9 V. I am using 12V. Is it correct ?

A silly thing that happened assembling this board is the following: I recently got an LCR meter, capable of measuring also ESR. So I bought two capacitors, a Nichicon Fine Tune bla bla 100 uF and some surplus cap. The Nichicon costs 20 times more than the other.
If I measure them, the Nichicon are closer to 80uF and have 0.7 ohm of ESR, the others are around 95uF and 0.4ohm ESR.
What would you use ?


Best Regards,

Davide
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Old 28th November 2010, 03:05 PM   #45
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By the way, I am using one 10 ohm 3W resistors (wirewound) to set the current. I expect to have around 300mA. Is it OK ?

THX,

Davide
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Old 28th November 2010, 03:18 PM   #46
Salas is offline Salas  Greece
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More like 200mA with 10R usually. Use the 0.4 ESR.
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Old 28th November 2010, 03:20 PM   #47
AndrewT is offline AndrewT  Scotland
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if the 80uF is outside specification, send it back and demand refund.
Or Demand refund and let them collect if they think them worth retrieving.
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Old 30th November 2010, 12:25 AM   #48
Horio is offline Horio  United States
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I'm planning to hot-rod my DCB1, and I'd like to run it at 600mA (3.3ohm resistors). I'm planning bolt the MOSFETs to a custom chassis with a 6mm thick bottom panel. The board layout doesn't really allow for mounting the rectifier diodes to the bottom panel. Do you think I could get away with running it at 600mA if I put some of these on the MUR820's I have? It isn't much, but I could bend the fins out to create a flat heat-sink.
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Old 30th November 2010, 12:56 AM   #49
Tea-Bag is offline Tea-Bag  United States
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You've got the right idea, there is not much space if you mount the TO-220's there.
If you can't get those sinks to bend that way, and my experience is that alum is not too pliable, I would use some of the 6mm chassis and 4/40 tap and just add some surface area to it.
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Old 30th November 2010, 04:31 PM   #50
johnm is offline johnm  United Kingdom
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Can the mosfets not just be desoldered, and instead mounted to the underside of the board (so bending the legs UP to fit the PCB)? I would have thought that would then easily allow it to be mounted to the chassis base, and allow that to be used as the heatsink?

- John
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