[sdiy] How available are these parts to you?

[James Patchell]

In general...yes...but there are some circuits that use the CA3080 that the 
CA3280 will most likely not work in.  If you tie the Id pin to the negative 
rail, this will disable the linearizing diodes.  One example of a circuit 
that will most likely not work with the CA3280 is the VCA circuit on the 
ASM-1 board.  And if it does work...it would not be cost effective.

At 09:33 AM 1/6/2006 -0600, phil macnutt wrote:
>Sorry to be the dunce, but can I use a CA3280 instead of a CA3080 in any
>circuit?  Advantages?  Disadvantages?
>I tried comparing datasheets, but I just did not understand all the details
>enough to make a decision.
>
>phil
>
>-----Original Message-----
>From: owner-synth-diy at dropmix.xs4all.nl
>[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of Ian Fritz
>Sent: Friday, January 06, 2006 8:51 AM
>To: Ray Wilson; Synth-Diy
>Subject: Re: [sdiy] How available are these parts to you?
>
>Hi Ray --
>
> >How hard do people perceive getting these parts to be on a scale of 1 to
> >10. With 1 being hard/expensive to 10 being easy/not-as-expensive. I'm
> >working on something new and I want to make it so that the parts are as
> >available as possible.
>
>This is pretty subjective and of course the situation is always dynamic.
>
> >1) LM3080
> >2) CA3080
>
>These are exactly the same thing, as far as I know.  They are getting
>harder to find and more expensive as time goes by.  Rate as  6.
>
> >3) CA3280
>
>Futurelec has these, and at an incredibly low price.  Your
>price/performance ratio is the best with this option.  However it is pretty
>hard to find this chip anywhere else.  I'd say get as many of these as you
>will ever need and do it right now.  Right now rate as 8, but if Futerlec
>stops selling them, much lower.
>
> >4) LM13600
>
>Don't know of any current source.  Rate as 1.
>
> >5) LM13700
>
>This is under production in Japan, as I hear.  Also a fair amount of old
>stock seems available.  Rating: 10.
>
> >6) Roll your own simple transconductance amp with transistors/op amps.
>
>This is not too hard to do, but if you want performance comparable to
>CA3280, say, you need to use very well matched transistors (< 50uV).  So it
>depends on what you are doing and how much offset variation you can
>tolerate.  Rate at 7.
>
>You should also note that the NE5517 is currently being produced by ON
>semi.  I got some from them directly.  Rating: 10.
>
>    Ian

         -Jim
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