Re: Do I have the Right Chip for my TDX Board

[Rubywand <rubywand@swbell.net>]

All Righty writes ...
> 
> Okay here is the deal. I wanted to have the completely homemade feeling
> of making my own Stereo Board for my Apple IIgs (I just love the thing),
> so I got all the components short of the Apple circuit board (I'll just
> etch my own),

     You can do that; but, it may be easier to use a stock prototyping board
and do most of the wiring with wirewrap wire. (Except for power leads. Use
something like 20 gauge wire for jumpers/connections to IC power pins.)



> but I have a question about the main chip in question.  I
> went to my local nerdy electronics store (no, not Radio Shack.  The guys
> there didn't even know what an "IC" was), and took a schematic for the
> TDX Stereo IIGS board, so I could get was the "Analog MPX 14052B"
> 
> There were a bit puzzled, and at first sent me me the wrong chip.  But I
> gave them a second chance.  Then they sent me a "NTE4052BT CMOS, Analog
> Differential 4-Channel Multiplexer".  The thing that concerns me is that
> I though the thing was going to be a little bigger..  The chip I have is
> a SOIC 16-pin surface mount.  Isn't the chip suppose to be a socket
> maybe.  If so tell me a good place to obtain a chip, that is reputable
> 
 ....

     It sounds like you got the right IC in a slightly inconvenient package.

    "40xxx" generally identifies a family of small/medium integration CMOS
logic IC's. (Like "74xxx" identifies a popular family of TTL logic IC's.) 
"140xxx" is the same as "40xxx". (I think Motorola is the one who introduced
the "140" prefix.)

     Of course, there is no forced standardization for chip designations; so,
you can find memory, etc. IC's which also begin with "40". When you order
IC's, it's a good idea to specify the full identifier (including any
letters), the function, and, if possible, the page number of the catalog
you're ordering from.

     The basic name of the IC is 4052 (or 14052).  The "B" indicates a more
rugged version. You can find a listing of 40xx family CMOS logic IC's from
Texas Instruments on page 71 of Digi-Key's current catalog. (The "CD4052BE"
is a 16-pin Dip package chip priced at $0.84.)  You can find a similar
listing in a catalog from Mouser and some other vendors.

     The TL082 OpAmp in 8-pin Dip package is listed on page 75 of Digi-Key's
catalog as TL082ACP.

     All of the capacitors should have a voltage rating in, roughly, the 15V
to 25V range.

     See http://home.swbell.net/rubywand/A2FAQs3VENDORS.html for links to
Digi-Key, Mouser, and other parts sellers.



Rubywand