RMI-FC100, a single stage audio power amplifier - Page 101 - diyAudio
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Old 22nd September 2010, 05:48 AM   #1001
housing is offline housing  Hong Kong
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Quote:
Originally Posted by Sheldon View Post
Just there to thermally couple the transistors and the diode. It's a refinement more than a necessity, as they are touching anyway. The thermal time constants are fairly large compared to music signals, so they just keep bias drift lower. You can use heatshrink tubing there, as the total dissipation is low.

Sheldon
Thanks, Sheldon. I'll stick to the heatshrink tube there.
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Old 24th September 2010, 09:41 AM   #1002
pooge is offline pooge  United States
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Roender,

This post advocates using red LEDs instead of green ones. If what this post says is true, could you suggest modifications to your amp to accommodate a change from green to red? Thanks.

OpenLoop Gain and compensation
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Old 24th September 2010, 10:14 AM   #1003
wahab is offline wahab  Algeria
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Somewhat marketing like annoucements...

This amp is an authentical TWO stages amp ,
providing we count the cascoded differential as
a single stage..
This latter provide 20 db of OL gain, while the
VAS bring the remaining 74db OL gain to reach
the 94db total OLG.
Attached Files
File Type: zip RMI FC100 STAGES OL GAIN.zip (7.9 KB, 203 views)
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Old 24th September 2010, 04:16 PM   #1004
Sheldon is offline Sheldon  United States
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Quote:
Originally Posted by pooge View Post
Roender,

This post advocates using red LEDs instead of green ones. If what this post says is true, could you suggest modifications to your amp to accommodate a change from green to red? Thanks.

OpenLoop Gain and compensation
The LED's set the base/emitter voltage. To maintain the specified current, just change the emitter resistor along with the LED.

Sheldon
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Old 25th September 2010, 08:56 AM   #1005
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by Sheldon View Post
The LED's set the base/emitter voltage. To maintain the specified current, just change the emitter resistor along with the LED.
and measure the current through the resistors to check it matches the design value.
This is where builders can benefit from three builders' schematics.
Basic to understand the circuit.
Voltage values added for error checking.
Current values added for error checking.

Most solid state circuits depend on current values through various components to determine overall performance.
If this information is missing then the builder never knows if his clone matches the Designer's Performance Targets
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Last edited by AndrewT; 25th September 2010 at 08:59 AM.
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Old 26th September 2010, 12:18 PM   #1006
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Hi.

Does anybody know if one NJL diode must be bypassed, than perhaps we can use NJW device instead as they have the same die (for one device only)?
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Last edited by AndriyOL; 26th September 2010 at 12:38 PM.
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Old 26th September 2010, 03:35 PM   #1007
Sheldon is offline Sheldon  United States
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Quote:
Originally Posted by AndriyOL View Post
Hi.

Does anybody know if one NJL diode must be bypassed, than perhaps we can use NJW device instead as they have the same die (for one device only)?
You could do that, but why? BTW, you'd have to redesign the PCB or twist the device leads around - they are not in the same order for NJL and NJW.

Sheldon
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Old 26th September 2010, 05:17 PM   #1008
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Quote:
Originally Posted by Sheldon View Post
You could do that, but why? BTW, you'd have to redesign the PCB or twist the device leads around - they are not in the same order for NJL and NJW.

Sheldon
They are cheaper and more easy to find when you are going to built HT. NJL types aren't available for now.
Btw, where you found that they are not in the same order. NJW datasheet lack of pin alignment. Maybe in Onsemi forgot about it.
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Old 26th September 2010, 05:53 PM   #1009
housing is offline housing  Hong Kong
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Quote:
Originally Posted by AndriyOL View Post
Btw, where you found that they are not in the same order. NJW datasheet lack of pin alignment. Maybe in Onsemi forgot about it.
NJW0281/0302
http://www.onsemi.com/pub_link/Collateral/340AB.PDF

Compare it with the datasheets of NJL's with pin alignment.
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Old 29th September 2010, 02:44 PM   #1010
zdr is offline zdr  Belgium
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What are the chances that these are real, as filtering caps for power amp:

2PCS Nichicon KG Gold Tune Audio Capacitor 10000uF/50V [KG Gold Tune 10000uf/50V] - $20.00 : DAC,Audio Amplifier,Hifi Amplifier,Tube Amplifier,Hlly Audio, Hlly Electronics
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