Millett "Starving Student" hybrid amp
May 19, 2008 at 3:06 AM Post #271 of 7,277
Quote:

Originally Posted by royewest /img/forum/go_quote.gif
OK, I just finished ordering the parts for this, except for the:

150uF 63V low-ESR electrolytic capacitor

Which are backordered at Mouser. I'll try my local shop, but any suggestions for alternate parts for C1,C3,C5,C6?

Thanks,

__Roy



Absolutely. If you read Pete's latest post, he suggests 470uf for the electrolytics on the power side anyway. Meanwhile, 470uf's have been a traditional output cap for Milletts for a long time, anyway. So, get yourself four 470uf 63V Nichicon UPW's. Mouser Part#647-UPW1J471MHD3 - $1.23 each.
 
May 19, 2008 at 5:39 AM Post #274 of 7,277
Quote:

Originally Posted by bhjazz /img/forum/go_quote.gif
I found a few old-school smoke shops in Seattle, and was considering a cigar box.


Not that quoting myself is a good thing, but I did figure something out. Funny how the human brain can digest ideas and come up with a good solution.

If a wood or wood cigar box needs to be used (to try to stay within the starving student idiom) consider mounting a piece of sheet metal to the inside of the box. This would create a simple RF shield, plus the heatsinks could be mounted to, and soldered to, the metal.

wink.gif
 
May 19, 2008 at 8:59 PM Post #275 of 7,277
Got my BOM pretty much sorted now. Slightly more expensive than the MSSH was supposed to be i think, but then that a consequence of living in England and some of the parts i chose.

Im also going to incorporate an alien DAC i've had lying around for about 7 months and an input selector. Figure i might as well get maximum functionality out of it. Just got to hope i still have some cash come end of June for all this!
 
May 20, 2008 at 12:44 AM Post #276 of 7,277
Just FYI, I called around a bit today looking for matched tubes. One of the vendors I called was in the process of making up an order for 40 tubes from someone. All the folks I spoke with asked what the sudden rush was on these tubes. I wonder how long this project will be viable if all the tubes are getting bought up -- I have no idea what the backstock of these tubes is.
 
May 20, 2008 at 2:11 AM Post #277 of 7,277
Quote:

Originally Posted by royewest /img/forum/go_quote.gif
Just FYI, I called around a bit today looking for matched tubes. One of the vendors I called was in the process of making up an order for 40 tubes from someone. All the folks I spoke with asked what the sudden rush was on these tubes. I wonder how long this project will be viable if all the tubes are getting bought up -- I have no idea what the backstock of these tubes is.


Could be Jeff is making kits? From the checking I've done, though, it will take a lot more than 40 tubes to make a dent in the 19J6's out there.
 
May 20, 2008 at 3:15 AM Post #278 of 7,277
Quote:

Originally Posted by tomb /img/forum/go_quote.gif
So, get yourself four 470uf 63V Nichicon UPW's. Mouser Part#647-UPW1J471MHD3 - $1.23 each.


I was trying to be all slick and headed out to Handmade Electronics, hoping to order some Nichicon Muse ES caps in 470uF. Joke's on me. None there. I thought I had seen that value there just last week.... Ah well. I'll go with the UPWs and wait for some ESs to show up in the future, although I'm not sure that they are available at anything over 50V.


Quote:

Originally Posted by royewest /img/forum/go_quote.gif
All the folks I spoke with asked what the sudden rush was on these tubes.


SAY NOTHING!!!!!!!!!!!

DIY Club = Fight Club
 
May 20, 2008 at 3:32 AM Post #279 of 7,277
Quote:

Originally Posted by tomb /img/forum/go_quote.gif
If you look closely, Pete soldered his to the copper board that's in his BOM. This sandwiches the tin between the bottom of the heat sink and the copper board. This is probably a convenient and easy way to do it.

On the other hand - if you look at Nate's pics, he used screws. Unfortunately, I think we're stuck with pulling the pins out if you go that route. I didn't see any "no pin" options for the size heat sinks we need at Mouser or DigiKey.

BTW, heat sinks are soldered to PCB's on a regular basis (almost all of the MAX's are built that way). The only reason you might want to remove them is if you decide to use a different size.



good luck getting the pins out. Just turn it upside down and tap the other ends of the heat sink and drill out a new hole to attach the device to.
 
May 20, 2008 at 5:13 AM Post #281 of 7,277
That's probably a bad idea. The pad is meant to work on its own. Adding more stuff between the metal surfaces will only reduce heat transfer.
But arctic silver is really good stuff. I've used that many times for heatsinks. Just use one or the other
smily_headphones1.gif
 
May 20, 2008 at 5:36 AM Post #282 of 7,277
Quote:

Originally Posted by royewest /img/forum/go_quote.gif
Just FYI, I called around a bit today looking for matched tubes. One of the vendors I called was in the process of making up an order for 40 tubes from someone. All the folks I spoke with asked what the sudden rush was on these tubes. I wonder how long this project will be viable if all the tubes are getting bought up -- I have no idea what the backstock of these tubes is.


wink.gif

I think that was me... Radio Daze right?

I've got something up my sleeve
very_evil_smiley.gif

It's strictly not-for-profit.
 
May 20, 2008 at 5:46 AM Post #283 of 7,277
Quote:

Originally Posted by rds /img/forum/go_quote.gif
That's probably a bad idea. The pad is meant to work on its own. Adding more stuff between the metal surfaces will only reduce heat transfer.......Just use one or the other
smily_headphones1.gif



umm are you sure? quoting the Millett Max site: "The choice of pad almost becomes one of convenience. Mica is the cheapest by far, but needs grease. Thermafilm has better heat transfer than Mica, but costs more and still need grease. Thermasil is the one that does not need grease, and often comes with an adhesive back, making it very convenient. "

MAX Heat Sink Mounting check the 4th paragraph. I wanted to get Thermafilm for this reason but I didn't wanna wait for mouser to get them back in stock
 
May 20, 2008 at 6:06 AM Post #285 of 7,277
I'm sorry, yes, with Thermafilm you will need grease as they say. I would imagine any thermal compound will be fine, but I'm no expert on that.
Keep in mind that the thermafilm itself is meant to electrically isolate Q1 and Q2 from the heatsink. If the heatsink itself is isolated from the circuit then the thermafilm is not required.
...hope that makes sense.
 

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