AW: Analogue multiplier - RC4200N

[Haible Juergen]

	>Just browsing through the maplins catalogue now and I've come
across
	>this RC4200N which is "... three op-amps specially designed for
	>multiplier logging circuits and offering complete compensation
for non-
	>linearity ... the nominal relationship between the three inputs
and the
	>output is l3 (o/p) = l1 x l2 / l4."
	>
	>With external trim, the total error as multiplier is +- 0.2%,
without
	>trim its <+-3%
	<
	>Does this sounds like a good thing for stable cv conversion? It
costs
	>6.50 like, which is fairly pricey, but it's only 2 quid more
than a
	>tempco resistor...

CV conversion - you mean the exponential converter ?
No, this wouldn't work.

The 4200 uses expo and log functions *internally* (for
multiplication and division functions), and so the tempcos
of exp() and log() cancel in the end.

But not for expo conversion.

JH.