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Part Sourcing Assistance/Advice Thread


n_maher

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I got a number of hits searching on “pcb busbar”, including this one on stackexchange: https://electronics.stackexchange.com/questions/59735/creating-a-high-current-bus-on-a-pcb
(Sorry, Hand-typed, hopefully works. Also, I’ve been out of town and didn’t take a close look at your pics).



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I was interested in the copper bar used to hold the silicon devices to the heat sink.  Pretty neat idea I had not seen before.  Of course, it requires a board layout that leaves room for that bar to avoid conflict with resistors, etc.  Also requires that all devices under the bar are the same thickness which may not be the case when mixing different devices to the same heatsink.  I does have the advantage of drawing heat away from both sides of the device.  And no need for peek screws!    

I wonder if devices are even engineered to take compression like this, vs just being held down by the hole mounting built into the device?  

concentra-3.jpg.385fee32076f301d2f5aa0d7d5817acc.jpg

Edited by Blueman2
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54 minutes ago, Blueman2 said:

I was interested in the copper bar used to hold the silicon devices to the heat sink.  Pretty neat idea I had not seen before.  Of course, it requires a board layout that leaves room for that bar to avoid conflict with resistors, etc.  Also requires that all devices under the bar are the same thickness which may not be the case when mixing different devices to the same heatsink.  I does have the advantage of drawing heat away from both sides of the device.  And no need for peek screws!    

I have seen the same used on discrete power amps with a thick and "spongy" thermal pad on the bar to even out the differences in thickness. Then it was possible to clamp e.g. both Sanken MT200 power transistors and TO-220 VAS transistors with the same bar.

54 minutes ago, Blueman2 said:

I wonder if devices are even engineered to take compression like this, vs just being held down by the hole mounting built into the device?  

I would think that's fine. It also puts the clamping force directly on the body of the device and not on the flange, so there should be less risk of having devices that aren't completely flat against the heat sink (which would lead to thermal instability).

Edited by UFN
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On 3/2/2019 at 3:30 PM, MartinC700 said:

Looking for PZTA06 transistors for a Carbon build. They are backordered everywhere. Anyone got 8 they can sell?

Regards

 

Ran out of spares but there should be plenty of substitutes, BCP56 should work and mouser has hundreds of thousands in stock.

On 3/2/2019 at 5:48 PM, Scgorg said:

Looking for PCB terminals (soldered on and with screws for wire) for my KGSSHV. Pin spacing is 5mm. Can't find anything rated for high voltages, everything seems to be 150/250V.

Did you check Mouser?  https://www.mouser.com/ProductDetail/Phoenix-Contact/5452258?qs=%2Fha2pyFaduhOh6w07UJSvZXaAYETWGY9mxlNZpKiRtk%3D

Edited by mypasswordis
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On 3/2/2019 at 12:30 PM, MartinC700 said:

Looking for PZTA06 transistors for a Carbon build. They are backordered everywhere. Anyone got 8 they can sell?

Regards

 

I should have some. I need a bunch so I don't know what I can spare. Also I'll only sell with the PZTA56 complement.

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Here's a plug for Arrow Electronics as a source for components. They don't seem to offer quite as broad a selection and Mouser, but pricing is generally better and shipping (at least to the US) is free and overnight regardless of order value. What is interesting is that parts in the same order often arrive in multiple overnight express packages from multiple locations. One order I placed had parts delivered from Las Vegas and Holland. 

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Yes, been using Arrow for quite some time now when they have what I need. A bit maddening to see a somewhat small order split into several shipments, each in considerably oversized packages with too much packing :) and this even when everything is a “ships tomorrow from the US” item...


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Never underestimate the obfuscating twats on diyaudio :indra:

I asked a question regarding Kemet vs. Vishay-Polytech tantalum-polymer capacitors (since the Vishays are considerably cheaper and appear to be functionally identical), and get this:

Quote

Isn't that a conflict mineral? I stopped using tantalums in years ago for that reason.
Aren't there alternatives?

Well, maybe, but given the thousands used in the automotive and consumer electronics areas, 8 of these isn't going to make a dent. So I replied with this:

Quote

This is for a mostly SMT headphone amp (Gilmore mini SS Dynalo), and the tants are what was specified. I hadn't anticipated the obfuscation on the question... perhaps if I had realized that I would have added "the moral quandary" to the title.

Given the many thousands of these used in the automotive and electronics industry, I don't think I'm going to worry about buying 8 of them for this application for which they are functionally and technically a very good fit. I'll take a look at both manufacturers websites; perhaps Kemet charges more for a more moral sourcing of their tantalum.
I was a technician in the '80s for a semiconductor manufacturer, and saw plenty of the old wet tantalums blow up and start on fire, so I used to avoid tants like the plague. However, recent builds have shown them to perform quite well for power bypass duties.

Perhaps a better moral question would be the horribly flawed EU lead study which resulted in ROHS. Arguably, this has contributed to millions of tons of failed consumer electronics clogging landfills. The US military still does not allow lead-free in its equipment, and I don't use the crap either.

Perhaps just answer the fucking question? That forum drives me up a tree, but there are SOME very good an knowledgeable posters there. In their defence, I had provided the wrong Vishay part number. I'll see what happens when they wake up...

And both Kemet and Vishay say that they source materials in a sustainable and conflict-free fashion. With Kemet, I can believe that. Vishay, being the sluts that they are, will say anything... kinda like the orange turd in the WH.

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