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Old 23rd December 2011, 06:35 PM   #91
AndrewT is offline AndrewT  Scotland
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I cannot follow any of your logic.

If the schematic shows +-34Vdc, what do you expect the maximum signal available at the speaker terminals when driving 8r0 with a sinewave test signal?

I would expect <30Vpk and more probably <26Vpk.

Can you really expect a passive heatsink of ~ 3"high by 3"wide by 1"deep (15mm fins) to dissipate at the rate of 0.8C/W?

I see part of my error in reading your dimensions.
25 = 1", NO!
25 = centimetres !!!
250 = ~10"
25 = ~1"
25cm = ~ 10"
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Last edited by AndrewT; 23rd December 2011 at 06:37 PM.
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Old 23rd December 2011, 06:40 PM   #92
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Quote:
Originally Posted by AndrewT View Post
If the schematic shows +-34Vdc, what do you expect the maximum signal available at the speaker terminals when driving 8r0 with a sinewave test signal?
That is exactly my question. You are not being helpful.

Quote:
Originally Posted by AndrewT View Post
Can you really expect a passive heatsink of ~ 3"high by 3"wide by 1"deep (15mm fins) to dissipate at the rate of 0.8C/W?
Are you blind? The heat sink is 10" long. Take the time to look at the diagram before you open your mouth.

/Mason

Last edited by greenm01; 23rd December 2011 at 06:43 PM.
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Old 24th December 2011, 05:58 AM   #93
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Default heat sinks...

Quote:
Originally Posted by greenm01 View Post
Are you blind? The heat sink is 10" long. Take the time to look at the diagram before you open your mouth./Mason
I apologize for being harsh; I believe we may simply have a breakdown in communication. Happy Holidays and good will!

I ran the LTSpice simulation, located in the original FC-100 thread, and found the following max power outputs (before output sine started clipping)
  1. 60W @ 8 ohms
  2. 120W @ 4 ohms
Using the approximation that the class AB output stage will dissipate ~46% (via Bob Cordell's text, page 104) of max rated power as heat, at 1/3 output power (assuming a 60C max heat sink temperature @ 25C ambient), I get the following thermal resistance (smaller requires larger sinks):
  1. 1.2 C/W for 8 ohm loads
  2. 0.6 C/W for 4 ohm loads
It never hurts to overcompensate thermally with larger heat sinks, but when space and budget are serious considerations I believe these are realistic numbers. I only plan on using 8 ohm speakers, so my heat sinks and chassis will not have to be very big.

Attached is the LTSpice simulation for your reference.

/Mason
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File Type: jpg rmi-fc100v1.JPG (88.4 KB, 578 views)
Attached Files
File Type: zip fc100_LTSpice.zip (79.9 KB, 54 views)
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Old 24th December 2011, 12:53 PM   #94
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Gentlemen,

while I am waiting for Santa Claus to climb down the chimney, I like and show you a picture of METAL's and my progress:

Click the image to open in full size.

http://www.abload.de/img/both_1m7j9e.png

We will offer you these 2 PCBs:

1) the PSU (on the bottom of the picture; its size is: 170 x 85mm)
2) the AMP (on top of it; its size is 143 x 73mm)

The PSU includes:

1) the backend PSU
2) the frontend PSU (Mihai's shunt regulator)

We still have to settle upon several questions:

1) Where to combine the Backend-Power(VCC and VDD) - GND planes? On the AMP PCB, on the PSU PCB?
2) Where / how to connect the Backend-Power - GND to the Frontend-Power GND? On the AMP PCB, on the PSU PCB?
3) Where to connect Speaker's Return? To the AMP PCB, to the PSU PCB?
4) Where / how to connect the different GND-planes to the Power Earth / Safety - STARGROUND?

When these questions are answered, we are done.

I wish you all a happy Christmas - Rudi_Ratlos
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Old 24th December 2011, 04:03 PM   #95
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Quote:
Originally Posted by Rudi_Ratlos View Post
the PSU (on the bottom of the picture; its size is: 170 x 85mm)
Do you happen to have a schematic of the PSU?

BTW, excellent job. I'm very much looking forward to having these boards in my hands!

/Mason
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Old 24th December 2011, 07:19 PM   #96
Bob03 is offline Bob03  Canada
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Default Capacitor holes

Hi Rudi,

To make your PSU boards more universal, could you please implement support for different capacitor pin-outs (like Peter Daniel on his PSU board).

F5 pcb group buy...

I wish you all a happy Christmas,


Bob03
Attached Images
File Type: jpg power supply.jpg (97.1 KB, 495 views)
File Type: jpg power supply 2.jpg (95.4 KB, 473 views)
File Type: gif untitled.gif (66.7 KB, 459 views)

Last edited by Bob03; 24th December 2011 at 07:35 PM.
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Old 26th December 2011, 10:53 AM   #97
zdr is offline zdr  Belgium
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Rudi, you still have two bjts near 470uF facing the same direction instead each other.
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Old 26th December 2011, 11:57 AM   #98
Ferrari is offline Ferrari  Netherlands
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zdr, make yourself a fresh cup of coffee, sit back, take a close look at the photo's on post #3, #4 and
the schematic on post #8 of Roender's amp thread and you will find the answer yourself.
Rudy has also answered your question in post #61 of this thread.
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Old 26th December 2011, 12:12 PM   #99
AndrewT is offline AndrewT  Scotland
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Ferrari Zdr,
you have confused me.
Should the BJTs be facing each other or facing away?
How were they on the Roender PCB?
Is Rudy's PCB the same or different?
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Old 26th December 2011, 12:13 PM   #100
zdr is offline zdr  Belgium
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You are referencing very early stage of Mihai's thread, lets take a look at some newer photos together. Am I missing something here?
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File Type: gif 2011-12-26_130736.gif (24.0 KB, 173 views)
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