Extender PCB's

amplifierguru · 13th December 2005, 05:02 AM

During the course of panellising my amplifier board artwork for production, I am often left with narrow slivers of waste space, I pay for. So I devised these long narrow extender boards for mounting 2 sets of 3 IRFP MOSFETS or anything in the same package. The drains and sources are paralleled to suit matched devices and they are all through hole plated and solder masked both sides. They have the correct 5.5mm pin spacing.

To neaten up your project - or add HD output stage.

They're free to anyone interested (MOSFETs not included) - max 4!

See Pic -

Cheers,
Greg

amplifierguru · 13th December 2005, 05:47 AM

Here's the artwork for a better idea -

Upupa Epops · 13th December 2005, 06:09 AM

You don't use gate stopper, Greg ? Where is gate's inlet ? Blocking capacity at drains ?

amplifierguru · 13th December 2005, 06:21 AM

Hi Pavel,

The gates are not connected to anything but there is a thin track to solder 1/2W resistors from the pad to common track. There just wasn't any room to provide for the AXIAL0.4 R's.. It's just to tidy up extensions of power stages. 3 pair.

Another thread a while back we discussed boosting the SKA for low Z loads with a conventional SF output stage by replacing the output fuses with 100R and driving 3 pair MOSFETS. It was about this time when I did the PCB but have never taken it further.

Cheers,
Greg

Upupa Epops · 13th December 2005, 06:36 AM

Are you using output fuses ? They have relative high resistance ( nonlinear )... Why not fuses at drain ?

amplifierguru · 13th December 2005, 06:53 AM

Yes Pavel,

i use +ve and -ve fuses from drains to output node, as it's common source. Thats why I can replace them with 100R resistor and drive a row of EF's with it - and they'd still be in the NFB loop. I haven't tried this yet and I thinkl the gain with 100R load or more instead of 8R might be a challenge.

Cheers,
Greg

Upupa Epops · 13th December 2005, 07:02 AM

CS configuration ? Have you good protected gates against overvoltage ? When one blow, feedback " pull " there full value of driving voltage...

amplifierguru · 14th December 2005, 02:20 AM

Hi Pavel,

Don't you worry about my CS output, both are proteced with 5V6 zeners on the gates and 10mA max current gate drive.

No takers for the extender boards?

Cheers,
Greg

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13th December 2005, 06:09 AM	#3
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	You don't use gate stopper, Greg ? Where is gate's inlet ? Blocking capacity at drains ?

13th December 2005, 06:21 AM	#4
amplifierguru Account Disabled Join Date: Aug 2004 Location: Earth	Hi Pavel, The gates are not connected to anything but there is a thin track to solder 1/2W resistors from the pad to common track. There just wasn't any room to provide for the AXIAL0.4 R's.. It's just to tidy up extensions of power stages. 3 pair. Another thread a while back we discussed boosting the SKA for low Z loads with a conventional SF output stage by replacing the output fuses with 100R and driving 3 pair MOSFETS. It was about this time when I did the PCB but have never taken it further. Cheers, Greg

13th December 2005, 06:36 AM	#5
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	Are you using output fuses ? They have relative high resistance ( nonlinear )... Why not fuses at drain ?

13th December 2005, 06:53 AM	#6
amplifierguru Account Disabled Join Date: Aug 2004 Location: Earth	Yes Pavel, i use +ve and -ve fuses from drains to output node, as it's common source. Thats why I can replace them with 100R resistor and drive a row of EF's with it - and they'd still be in the NFB loop. I haven't tried this yet and I thinkl the gain with 100R load or more instead of 8R might be a challenge. Cheers, Greg

13th December 2005, 07:02 AM	#7
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	CS configuration ? Have you good protected gates against overvoltage ? When one blow, feedback " pull " there full value of driving voltage...

14th December 2005, 02:20 AM	#8
amplifierguru Account Disabled Join Date: Aug 2004 Location: Earth	Hi Pavel, Don't you worry about my CS output, both are proteced with 5V6 zeners on the gates and 10mA max current gate drive. No takers for the extender boards? Cheers, Greg

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