[sdiy] How available are these parts to you?

[phil macnutt]

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