[sdiy] Tempco group buy news - Here's the deal!

[Metrophage]

Hi Glen,

> >1k, 1% - 315 pieces at $1.62 each
> >2k, 1% - 170 pieces at $1.92 each
> >
> >And - they can do 1.87k, 1% for the same pricing as 2k! 

First off, I am going to try to get cheaper prices from KRL tomorrow,
as many, many  more people have been interested. Tomorrow I will have
the final, final prices.

> Can someone give me a quick overview of which values are most useful
> for  which applications? I might want to get in on this group buy,
(if
> it's not too late), but I'm not sure which of the three possible
values I
> would want most for my future projects.

Most people use 1k tempcos these days as shunt resistors for current
designs. Look at some recent VCO schematics and you often see a 1k
tempco going to ground before the expo converter transistor pair.
That's basically what people use these for. And for similar
applications in VCLFOs and VCFs which people want to tune for 1V/octave
playing. 

In older VCO applications, people often used a 2k tempco in the
feedback loop of the summing amplifier, and trim them with a pot to get
1V/octave. Or use a 1.87k tempco in the feedback loop and hardly need
to trim it a all! This is all assuming the use of 100k summing
resistors, which is often the case.

I am sure that the many more knowledgable people on the list could
expound further upon this. There was some talk about it about 2 or
three days ago. If you are looking to build a certain circuit or repair
a synth, then I suggest looking for some schematics or looking under
the hood and seeing what it uses. If you want to design a VCO then it
is really up to you whatever you want to do. I'm using some of the 1k
for some kits I have here like ASM1 and EFM, and probably a few other
projects. I also want to try some older circuits from the few issues of
Electronotes which I have, and clone a few VCOs I've wanted to hear.
Those I'll likely use 1.87k or 2k. Maybe I'll devise a VCO of my own
this year!

CJ


		
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