RMI-FC100, a single stage audio power amplifier - Page 22

loek · 31st December 2007, 01:40 PM

I made this board with a millingmachine.
Now collecting parts.Happy 2008,
Loek

DRZ1 · 31st December 2007, 01:48 PM

oh milling machine you too

loek · 31st December 2007, 02:04 PM

Indeed. It is made by LPKF, a 91s.
Software is Circuitcam and Boardmaster.
As you see i did not remove all the copper, will use it as a groundplane.
Greetings, Loek

roender · 31st December 2007, 02:14 PM

Quote:

Originally posted by loek
I made this board with a millingmachine.
Now collecting parts.Happy 2008,
Loek

Hello Loek,
Don't worry about outside PCB dimensions holes. Two of them are from drivers, mje15034/mje15035, and are not in use.
I'm not sure if it is safe to implement ground plane. In the first stage, when you start the amplifier, try to not connect the plane to ground. See how it works and after that try to find a good point to connect such a huge plane to GND, maybe in main starground. Use a scope to track possible oscillations

Good luck and
Happy New Year!
Mihai

loek · 31st December 2007, 02:29 PM

Hi Mihai,I will start to connect it to starground with 0.1 uF or 10 ohm, but it can last a while ....
Thanks anyway, Loek

roender · 1st January 2008, 08:35 AM

After many hours of hard work, I've build another one for a friend of mine.
Transistors are not very well matched as in my versions - Carlos was wright about matching, offset is -2mV but sound the same as mine.

jackinnj · 1st January 2008, 01:37 PM

Quote:

Originally posted by roender

Hello Loek,
Don't worry about outside PCB dimensions holes. Two of them are from drivers, mje15034/mje15035, and are not in use.
I'm not sure if it is safe to implement ground plane. In the first stage, when you start the amplifier, try to not connect the plane to ground. See how it works and after that try to find a good point to connect such a huge plane to GND, maybe in main starground. Use a scope to track possible oscillations

Good luck and
Happy New Year!
Mihai

Speaking of ground planes and amplifiers -- I had some board made up for the LM4702 and LME49810 -- on one set I used a dual star system -- allowing the ground for the driver to be separated from the power ground by a small value resistor, for the second I poured copper. The THD+N% for the board with ground plane is measurably inferior to the dual-star system.

loek · 2nd January 2008, 10:13 AM

Thanks Jackinnj, i had this experience also with the first Leach boards. My FC100 pcb holes are not plated so easy to select the area i want for ground.
Did you read my PM?
Loek

jackinnj · 2nd January 2008, 11:56 AM

Quote:

Originally posted by loek
Thanks Jackinnj, i had this experience also with the first Leach boards. My FC100 pcb holes are not plated so easy to select the area i want for ground.
Did you read my PM?
Loek

was that about the spec analyzer?

loek · 2nd January 2008, 12:29 PM

No, it was about your post 210 in this thread..
You asked for a PM for the transistor offer, so i did.
Regards, Loek

31st December 2007, 02:29 PM	#215
loek diyAudio Member Join Date: Feb 2005 Location: The Hague	implement ground plane Hi Mihai,I will start to connect it to starground with 0.1 uF or 10 ohm, but it can last a while .... Thanks anyway, Loek

2nd January 2008, 10:13 AM	#218
loek diyAudio Member Join Date: Feb 2005 Location: The Hague	board with ground plane Thanks Jackinnj, i had this experience also with the first Leach boards. My FC100 pcb holes are not plated so easy to select the area i want for ground. Did you read my PM? Loek

2nd January 2008, 12:29 PM	#220
loek diyAudio Member Join Date: Feb 2005 Location: The Hague	pm No, it was about your post 210 in this thread.. You asked for a PM for the transistor offer, so i did. Regards, Loek

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31st December 2007, 01:48 PM	#212
DRZ1 diyAudio Member Join Date: Jan 2007 Location: Quebec City	oh milling machine you too

31st December 2007, 02:04 PM	#213
loek diyAudio Member Join Date: Feb 2005 Location: The Hague	Indeed. It is made by LPKF, a 91s. Software is Circuitcam and Boardmaster. As you see i did not remove all the copper, will use it as a groundplane. Greetings, Loek

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