A/D project

Archiver

I'd like to work up a small A/D project. Microchip make stamps with
the A/D inbuilt which sounds great. Is it wise to have some external
regulator to limit the voltage the chip experiences or can I hook the
signal straight uo to the chip.

Thanks in advance

Grant McPherson

Home of the ROVER remote control
www.ozsonic.com

Archiver

Grant,
CMOS doesn't like over-voltage, so it's good to buffer the signal. I use
a 0 to 5 volt rail-to-rail op amp for that purpose into a 12-bit A/D
converter. Zero is offset to about 2.048 volts with the 12 bits spanning
4.096 volts. I use the PIC to "watch" the drifting signal voltage and
trigger an analog reset towards 2 volts when the voltage gets close to
either rail. The net effect resembles a pong game, with the signal always
bouncing off a rail before it saturates there.
Dennis

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Original Message

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From: Grant McPherson <mcpherson@o...>
To: basicstamps@egroups.com <basicstamps@egroups.com>
Date: Wednesday, November 08, 2000 2:47 PM
Subject: [noparse][[/noparse]basicstamps] A/D project


>I'd like to work up a small A/D project. Microchip make stamps with
>the A/D inbuilt which sounds great. Is it wise to have some external
>regulator to limit the voltage the chip experiences or can I hook the
>signal straight uo to the chip.
>
>Thanks in advance
>
>Grant McPherson
>
>Home of the ROVER remote control
>www.ozsonic.com
>
>
>
>