Analog Devices VCA ???

[Tim Cockram]

I haven't used the 2018 in a battery powered device before sooo I can't comment specifically, but here goes any
way:- You'll need to make sure that there is adequate power supply decoupling and that the power rails are 
large enough to cope with the required signal range. 
As with all 2018 ccts make sure you do put the filter capacitor on the control port.
With regard to the law of the device one output will be dB linear the other won't.

On a different tack have you considered using analogue switches driven by a high frequency modulated pulse. 
This is a really good way of controlling amplitude if an attenuation of -20dB is OK.

Alternatively If you want a true deci-linear panner with a few parts try the Thats Corp 2151 etc series of 
vca's as they have copmplementary control ports (no inverters required).  They are current mode devices so they 
do require a current to voltage convertor on the output.  As far as layout is concerned they are great devices 
as they are single in line packages and require very few external components. 
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E-mail:- tim at redragon.demon.co.uk
Work:-   UK-1222-384041
Fax:-      UK-1222-225299
07:41:10
07/15/96

Sociology is the study of those who don't need to be studied by those who do.

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