RMI-FC100, a single stage audio power amplifier - Page 62

roender · 10th January 2009, 03:48 PM

Quote:

Originally posted by pooge

Is it one like this, stood up with the top lead bent over?

DO35 diode

Yep, that's it, do-35 package

pooge · 10th January 2009, 04:10 PM

Is the 1W requirement for this part correct in your BOM?

roender · 10th January 2009, 04:23 PM

It is correct. My diode is in a little large package, i think is DO-41 (2mm diameter) glass, but DO-35 500mV will suffice.
In fact, is not important how large this diode is, if it fit between TO-129 cascode devices

pooge · 10th January 2009, 05:30 PM

Great. That makes things easier. I was wondering why you specified a 1W part to carry only 1ma.

AndrewT · 10th January 2009, 06:12 PM

I was thinking a mechanical switch on the heatsink to trigger a latching relay to cut off power.
But using the diode as a fast warning that overheating is starting to occur,

pooge · 10th January 2009, 06:43 PM

Again. What about the wattage of the 36v zener in the front end power supply? Anything I find availabe in 1W comes in a DO41 package with .8mm dia leads that won't fit in the holes on the circuit board.

pooge · 10th January 2009, 06:48 PM

Quote:

Originally posted by AndrewT
I was thinking a mechanical switch on the heatsink to trigger a latching relay to cut off power.
But using the diode as a fast warning that overheating is starting to occur,

Or perhaps, in addition, use the signal to shunt the bias pot.

roender · 10th January 2009, 07:49 PM

Quote:

Originally posted by pooge
Again. What about the wattage of the 36v zener in the front end power supply? Anything I find availabe in 1W comes in a DO41 package with .8mm dia leads that won't fit in the holes on the circuit board.

I put in the BOM what I had in my parts box and used in my PSU.
If you do the math you'll see that at Vr 1mA that diode will dissipate 36mW, so 500mW glass case will be more than enough

pooge · 11th January 2009, 06:45 AM

About a year and a half ago there was a thread about thermal pads for TO264 packages like the ThermalTraks, and how no one new a source for any. It looks like after another year and a half, not much has changed.

I did find a mica one from Aavid that would appear to work, but I can't find any suppliers for small quantities. It is model number Aavid Mica Insulator #56-02-101

If anyone can find a source for it, a group buy may be in order. Any other suggestions?

pooge · 11th January 2009, 07:02 AM

Found some here. HUGE price break at 1000.

Mica insulators

Enter part # 56-02-101

10th January 2009, 06:12 PM	#615
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	I was thinking a mechanical switch on the heatsink to trigger a latching relay to cut off power. But using the diode as a fast warning that overheating is starting to occur, __________________ regards Andrew T.

11th January 2009, 06:45 AM	#619
pooge diyAudio Member Join Date: May 2003 Location: Northern Va.	Mica insulators About a year and a half ago there was a thread about thermal pads for TO264 packages like the ThermalTraks, and how no one new a source for any. It looks like after another year and a half, not much has changed. I did find a mica one from Aavid that would appear to work, but I can't find any suppliers for small quantities. It is model number Aavid Mica Insulator #56-02-101 If anyone can find a source for it, a group buy may be in order. Any other suggestions?

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10th January 2009, 04:10 PM	#612
pooge diyAudio Member Join Date: May 2003 Location: Northern Va.	Is the 1W requirement for this part correct in your BOM?

10th January 2009, 04:23 PM	#613
roender diyAudio Member Join Date: Sep 2006	It is correct. My diode is in a little large package, i think is DO-41 (2mm diameter) glass, but DO-35 500mV will suffice. In fact, is not important how large this diode is, if it fit between TO-129 cascode devices

10th January 2009, 05:30 PM	#614
pooge diyAudio Member Join Date: May 2003 Location: Northern Va.	Great. That makes things easier. I was wondering why you specified a 1W part to carry only 1ma.

10th January 2009, 06:43 PM	#616
pooge diyAudio Member Join Date: May 2003 Location: Northern Va.	Again. What about the wattage of the 36v zener in the front end power supply? Anything I find availabe in 1W comes in a DO41 package with .8mm dia leads that won't fit in the holes on the circuit board.

11th January 2009, 07:02 AM	#620
pooge diyAudio Member Join Date: May 2003 Location: Northern Va.	Found some here. HUGE price break at 1000. Mica insulators Enter part # 56-02-101

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