Help with circuit design

Apr 12, 2006 2 Replies
Z

Hi!



I have bought some motion sensors (called NaPiOn) but need some help in choosing the correct components when designing an output circuit.



The sensor is the 5V digital-output version:

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The manufacture have some examples on how to use the sensor. I'm just a little bit confused on how to calculate the correct resistance and how to determine which transistor to use (or which FET to use in example 2).



Look at the links for examples:

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I'm also interested in using a optocoupler - Does anyone know if its okay just to have this directly on the sensor output? Or does this damage the sensor?



Thanks in advance!



Zenty



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T

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The key parameter on the data sheet is the output current rating: 100uA for the digital, 50uA for analog. You need to provide an amplifier that will require less than that amount of current. They don't give any timing information, but my guess is that it is very very slow. 100uA and very slow means that you can use almost any general purpose transistor you want.

Your optocoupler will need an amplifier to boost the current, either internally (i.e. "logic input") or externally -- a single transistor amp will do, however.

Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/
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F

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The application diagrams are flawed garbage- they must have hired former Texas Instruments technical writers. Since you have digital output, a simple MOSFET drive of an optocoupler would look like this: View in a fixed-width font such as Courier.

. . . BATT-1.5 . Rs= --------= 390R . 0.005 OPTO . 4.5VDC +----------+ . .----------------+--------[Rs]-----------. | . | | | | |/ | . |+ | AMN1X11X | V ~ | | . --- +---------------+ | - |> | . - | BATT | +-|--------+ . | | | |d . 3xAA |+ | MP | |- . --- | SENSOR OUT|-----+-------| 2n7000 . - | | | g|- Vishay . | | | | |s . |+ | | [100K] | . --- | GND | | | . - +---------------+ | | . | | | | . | | | | . '---------------+--------------+---------+ . . . .

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