Design Article
Comment
G.K.
It looks to me more like an application from Maxim rather than a design idea ...
WKetel
The great place for this device would be going through airport security, to keep ...
Circuit keeps wandering children and pets nearby
Tom Au-Yeung and Craig Sakamoto, Maxim Integrated Products, Sunnyvale, CA; Edited by Martin Rowe and Fran Granville
12/2/2010 2:00 PM EST
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When the transmitter moves outside
the predetermined boundary, the detected
RF produces less than 400 mV at the
comparator. The comparator then generates
an output of approximately 3V,
which turns on the buzzer and sounds
an alert that the transmitter has moved
beyond the restricted perimeter. To increase
the detection range, you can place
additional low-noise amplifiers or VGAs
(variable-gain amplifiers) in front of the
power detector. You can also increase or
decrease the desired perimeter by adjusting
R10 to change the comparator’s reference
voltage.
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anonymous user
12/3/2010 2:59 PM EST
I've been looking for a circuit to do just this. Thanks guys!
A question though: Where can I get the parts if I only want to make one or two? I can get a sample for all of the IC's from Maxim except MAX2203. I can buy MAX9075 from Digikey and MAX2623 from Advet, but I can't purchase the other two unless I order 2500 or more. Could you suggest alternative IC's that readily available?
Thank you.
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anonymous user
12/3/2010 3:00 PM EST
Let's see if I understand this correctly; you have a transmitter running all the time, not gated on and off? I know that it's the "unlicensed band" but really, you want to have a carrier running all the time polluting the airwaves at this freq? And what do you run this from? The part draws nominally 8mA @ 3V; that'll last long... How about add a 6 pin micro gets attached and sends out unique codes, now you can "know" *what* device is out of range.
Secondly, these kinds of "designs" have been around for 50 years; there's a reason that you don't see them as a commercial device (with exceptions, every other few years or so someone puts one on the market and then promptly takes it off). It's a matter of insurance. In order to put a product out, you have to have insurance to cover the "what if's". Claiming that a product (and I recognize that this is a circuit and not a product) "keeps wandering children and pets nearby" is foolish at best. It will take one person to build this, attach it to their "dog" (I will not use a child for an example), the "dog" wanders out of range, in front of a car (whether the "circuit" alerted them or not) and now Tom Au-Yeung and Craig Sakamoto, Maxim Integrated Products, Sunnyvale, CA; Martin Rowe and Fran Granville and EDN are all named in a lawsuit (rightly so or not).
How about "keep your car keys nearby" or "don't loose your stapler" (ala' "Office Space"). Come on, you guys are smarter than this.
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WKetel
12/3/2010 3:15 PM EST
The great place for this device would be going through airport security, to keep track of one's computer. The buzzer will need to be very loud and able to sound long enough to chase down the punk that steals said laptop. Of course, the TSA may mistake it for a bomb and shoot the user.
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G.K.
1/23/2013 8:01 AM EST
It looks to me more like an application from Maxim rather than a design idea from an independent designer. Is it an advertisement of Maxim or what???
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