[bcollier]

Hi,

I'm trying to build two MINTs, and simply can't find the BUF634 SO-8 buffers anywhere. Digi-Key, Jameco, and everyone report that they won't have them for months, and the only type that ever show up on ebay are the DIP versions.

So, it seems to me that a dip to so-8 (assuming they exist) adapter might take up too much space, but are there any similarly specced buffers that would work, or even a source of these things that I have not yet discovered?

Also, does anyone know why all of these buffers have dropped off the face of the earth?

Thanks!

 

[ericj]

Ti says that they just, ran out.

They insist that it's a popular product that's not going to be discontinued any time soon, but it's apparant that they didn't anticipate demand, or had trouble with a production line, or something.

Some people are substituting an opa551 for the buf634 on PIMETA boards, you might search for those threads for information - it could be as simple as cutting a couple traces and allowing a solder blob to bridge two legs.

 

[cetoole]

Quote:

Originally Posted by ericj Ti says that they just, ran out. They insist that it's a popular product that's not going to be discontinued any time soon, but it's apparant that they didn't anticipate demand, or had trouble with a production line, or something.

Thats what they told me too when I spoke with one of their reps, didnt really explain why, but its definitly not EOL.

Quote:

Originally Posted by ericj Some people are substituting an opa551 for the buf634 on PIMETA boards, you might search for those threads for information - it could be as simple as cutting a couple traces and allowing a solder blob to bridge two legs.

Bridge pins 2 and 6, and dont use the bandwidth resistors. Everything else is the same I believe.

 

[bcollier]

Thanks for all the helpful info, but this is for a MINT and I'm having trouble finding OPA551s in an SO-8 configuration as well. Whatever I have to use, I really don't want two large dip to so-8 adapters hanging off of my MINT.

I flipped through some of those old threads about building a buffer, but again there are size constraints to deal with, as I'd like to fit dual 9vs into a mint tin with this amp.

Any further suggestions would be greatly appreciated.

 

[Pars]

Intersil HA5002s? I know the pinout is somewhat different. Newark carries them, and I think they are avail. in an SOIC-8 pkg.

 

[ericj]

Gosh, you're right. opa551ua is out of stock everywhere too. Ti thinks that Newark might have some, but Newark disagrees.

Well, it won't be as punchy as a 551 or 634, but you could always pick up some other so-8 single opamp and run with that.

Or just wait until the chips are back in stock some time next year.

Sux.

 

[bcollier]

I guess i'll end up waiting. Oh well, maybe ill do a CMOY or some other project in the mean time. Come to think of it, a home amp wouldn't be too bad of an idea.... my poor wallet.

Thank you all for your suggestions.

 

[cetoole]

Quote:

Originally Posted by Pars Intersil HA5002s? I know the pinout is somewhat different. Newark carries them, and I think they are avail. in an SOIC-8 pkg.

Pinout is quite different, and remember that there is no output protection on the HA5002 like there is on the BUF634, so it isnt really ideal for portable use, with 3.5mm sockets being as secure as they are, and the mint not having provisions for protection. A polyfuse could be wired to the battery input though to limit the current draw to safe levels, soft blow at 400mA or so.

 

[tigger]

Quote:

Originally Posted by bcollier Hi, I'm trying to build two MINTs, and simply can't find the BUF634 SO-8 buffers anywhere. Digi-Key, Jameco, and everyone report that they won't have them for months, and the only type that ever show up on ebay are the DIP versions. So, it seems to me that a dip to so-8 (assuming they exist) adapter might take up too much space, but are there any similarly specced buffers that would work, or even a source of these things that I have not yet discovered? Also, does anyone know why all of these buffers have dropped off the face of the earth? Thanks!

FWIW, You can get BUF634P here

and adapters here

 

[nikongod]

Quote:

Originally Posted by cetoole Pinout is quite different, and remember that there is no output protection on the HA5002 like there is on the BUF634, so it isnt really ideal for portable use, with 3.5mm sockets being as secure as they are, and the mint not having provisions for protection. A polyfuse could be wired to the battery input though to limit the current draw to safe levels, soft blow at 400mA or so.

you can always solder a 25 omega resistor in each of the lines for the output jack. right in the position of r8 in the mint schematic

not that it really matters though, as the mint is not compatable with those buffers, so a new board would have to be drawn up... and you could easily add the resistors.

 

[bcollier]

Quote:

Originally Posted by tigger FWIW, You can get BUF634P here and adapters here

Yes, i've seen both of those, but the adapters are giant

I mentioned earlier that i didn't want to use any, because i'm trying to fit my MINT in a mint tin with 2 9v batteries.

 

[amb]

While you wait for the BUF634U to become stocked again, you can operate the MINT like a cmoy by letting the first opamp stage drive the headphone directly. To do that, just add a temporary wire jumper between pins 3 and 6 at each of the BUF634U pads. When you get the BUF634Us, remove the jumpers and solder in the chips instead.

 

[bcollier]

Quote:

Originally Posted by amb While you wait for the BUF634U to become stocked again, you can operate the MINT like a cmoy by letting the first opamp stage drive the headphone directly. To do that, just add a temporary wire jumper between pins 3 and 6 at each of the BUF634U pads. When you get the BUF634Us, remove the jumpers and solder in the chips instead.

Awesome! I'll definately do that. I'm definately a newbie when it comes to this, so I'm not at the level when I can decide to jump things

 

[helix]

if your able to supply a little extra voltage to the rails may i suggest the AD815 or even the HA-5002, both are high bandwidth devices so the usual cautions apply.

 

[tangent]

Quote:

Originally Posted by amb just add a temporary wire jumper between pins 3 and 6 at each of the BUF634U pads.

You should also short R5 and leave R6 out while running the amp this way.