_[sdiy]_ICL8038 worst ic off all time!

[Scott Gravenhorst]

=?iso-8859-1?q?Karl=20Dalen?= <karldalen at yahoo.se> wrote:
> --- Scott Gravenhorst <music.maker at gte.net> skrev: >
>=?iso-8859-1?q?Karl=20Dalen?= <karldalen at yahoo.se> wrote:
>> >I cant understand why such a crap design are still made?
>> >Even a simple neatly done discreete design would out perform
>> >the 8038!
>> 
>> Well, I think the datasheet contains examples of the worst ways
>> to _use_ the 8038.  Check http://www.midwest-analog.com/diylvco.html
>> for what I would call the right way to use it.  The circuit has
>> a wider linear sweep range than the datasheet circuit and it also runs
>> cool.
>
>The worst way is to use it at all! :-)
>
>> >There should be a list of "worst-IC-designs-of-all-time" it would 
>> >also be nice with a list of the most "neat" IC design of all time to!
>> >In the first list i would definitively put the 8038 and a bunch of
>> >early FM chips! In the second list i would put the 555, the 4046.
>> 
>> 555, I agree, in fact, I'd put that on the "worst IC of all time" list.
>> The 7555, however is fine.  I like the 4046 used as a PLL, I built a
>> frequency multiplying module with one.  The VCO basically sucks by
>> itself. 
>
>Hmm, i dont think the VCO sucks,as i remember, BJ showed once many years
>ago that you could build a remakable advanced VCO out of a 4046 IC! Well,
>at least a "very high frequency LFO" with sync and 4 quadrant modulation
>on the square, if im not remebering completely wrong, thats not bad for
>such a cheap and simple IC. Or one could use the HC version and do a
>nice DC to 30Mhz function generator. I say forget about the 8038! 

Looking at the spec, a 4046 is rated at 1.3 MHz, the 74HC4046 version runs
at max 17 MHz.  The VCO is fine, it's the current source that isn't very
good.  Check the TI docs, it has a whole section on the technicals of
the VCO.

I built up that circuit by Bjorn Nilsson(?) and couldn't
get it to track a linear CV.

>Speaking of function generators, you can use a PNP expo on the I set 
>pin on the MAX038 to convert it to a expensive VCO!
>
>KD
>
>
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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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