MOTM

1. Do I need to match the transistors (should I order extras)?
2. The project calls for "100pf film caps." Can I use 0.1uF poly caps  
in their place?
3. If no, can I use these for the 0.1mf caps on the 390?

Thanks, -jl

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On 5/29/08, Jeff Laity put forth:
>1. Do I need to match the transistors (should I order extras)?

Besides the ones inside the SSM2210, I do not believe that the
transistors were matched.

>2. The project calls for "100pf film caps."

It doesn't.  The caps in the filter itself are 100nF, not 100pF.

>Can I use 0.1uF poly caps  in their place?

Well, 0.1uF is the same as 100nF.  Imho, "poly" is kind of a vague
term -- does it mean "polymer" or "polyester"??  While I don't know
exactly which capacitors it uses, I know it doesn't use the AVX
"yellow box" caps.  They are these little brown radial caps.

Anyway, the type you use will have an effect on the sound.  If no one
else chimes in, I can try pulling my 490 and see if there any
markings.  A better description or the manufacturer's part number
isn't listed on the BOM??

>3. If no, can I use these for the 0.1mf caps on the 390?

I have no idea :)

The official word from Paul is - ... I built one of these recently. You ll need 2 different kinds of these ECQ-V s - 220nf=.22uf, so that one is the P4667-ND,

On 5/30/08, Stephen Drake put forth:
>The official word from Paul is -
>
>>MOTM-410, MOTM-485, MOTM-490 stacked film, Panasonic ECQ-V type
>>0.22uf is P4667
>>0.33uf is P4669
>>0.022uf is P4517
>>0.047 is P4521
>
>I built one of these recently. You'll need 2 different kinds of 
>these ECQ-V's - 220nf=.22uf, so that one is the P4667-ND, and 
>100nf=.1uf, which is P4525-ND - both of these were from digikey. And 
>you will indeed need one yellow box cap - it's a 1nf, or 001.uf - 
>the standard kind, which is part 581-1N0J63 from mouser. The rest is 
>the standard stuff.

Thanks, I was only talking about the four filter caps.  So just so no 
one gets confused, while the 410 uses a bumber of different caps, 
including stacked film, the filter itself uses axial polystyrene. 
It's also a great module -- still one of my fovorites after all these 
years.

Speaking of caps....

Thank you. Part numbers are very helpful, especially for caps and  
semiconductors. (hint, hint)

I think poly = polypropylene. They're dark red like kidney beans. I  
was trying to avoid using Digikey but I'll go ahead and order a bunch  
of components for my next three projects.



> From: "Paul Schreiber" <pschreiber@...>
> Date: May 29, 2008 10:49:58 PM PDT
> To: "MOTM List" <motm@yahoogroups.com>, "Jeff Laity" <synthetic@... 
> >
> Subject: Re: [motm] 490 parts questions
>
>
>> 1. Do I need to match the transistors (should I order extras)?
>
> No, there are SSM arrays for the required matched pairs.
>
>> 2. The project calls for "100(0)pf film caps." Can I use 0.1uF poly  
>> caps
>> in their place?
>
> Poly as in mylar? ACK (shudder!)
>
>> 3. If no, can I use these for the 0.1mf caps on the 390?
>
> Use the correct part for both, they are cheap enough from Digikey  
> (part #P4525). And only 403,000 in stock :)
>
> Paul S.
>
>



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On 5/30/08, Jeff Laity put forth:
>Thank you. Part numbers are very helpful, especially for caps and
>semiconductors. (hint, hint)

Yes :)

>I think poly = polypropylene.

Afaik, the term "poly" when talking about capacitors refers to
polyester, meaning polyethylene terephthalate.

To a polymer chemist, polycarbonate (which is also used in
capacitors) and many other polymers are also polyesters.  To most
people, "polyester" means a polymer of one specific ester,
polyethylene terephthalate.  There are also different types of
polyethylene.  Mylar is a trade name of polyethylene terephthalate
film.

Polypropylene is not a type of polyester, because propylene is
an alkene, not an ester.  Neither is polystyrene, because ethyl
benzene isn't an ester either.  Both are used a dielectrics.

>They're dark red like kidney beans.

Yes, but they make terrible chile.

>I was trying to avoid using Digikey but I'll go ahead and order a
>bunch of components for my next three projects.

Jameco sells Panasonic ECQ-V.  They also sell OP275, twisted pair
wire, hook-up wire, and many other parts used in MOTM, at very
competitive prices.


>>From: "Paul Schreiber"
>><<mailto:pschreiber@...>pschreiber@...>
>>
>>Poly as in mylar? ACK (shudder!)

Sorry, I'm a bit confused by the "ACK (shudder!)" comment.  I know
that polyester is largely inadequate for many applications such as
VCO's, sample and hold, timing circuits, etc. due to its high DA and
poor temperature stability.   However, it seems that MOTM often uses
polyester caps for filters, coupling, etc.  The Panasonic ECQV are
listed as coated "metallized polyethylene terephthalate"  and the AVX
BF/BQ  "yellow box" caps are listed as "metalized polyester".