#20 in Household doors
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Reddit mentions of Chamberlain Liftmaster 41A4373A Safety Sensors
Sentiment score: 1
Reddit mentions: 2
We found 2 Reddit mentions of Chamberlain Liftmaster 41A4373A Safety Sensors. Here are the top ones.
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For garage door openers that currently have sensors installed41A4373A Sensors are compatible with LiftMaster and Chamberlain Brand from 1993 - late 1990'sEach sensor has a green light and a bolt that runs right through the center of each sensorDesigned to splice into your existing wiresIncludes 1-sending unit, 1-receiving unit, Wire connectors, and instructions - no brackets
Specs:
| Color | Black |
| Weight | 0.25 Pounds |
For the trip-beams, the easiest thing is to use garage door IR beam sensors. E.g. - http://www.amazon.com/gp/product/B0006N1RH6/ref=pd_lpo_k2_dp_sr_3?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B00283U19M&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=0W0VM31WZ4FE2T2X3607
I'm assuming these run on 12V or something close, but without one in hand I can't be sure. To supply 12V without running a power wire, a fully charged car or motorcycle battery will work.
But honestly, you'd probably be better off running the wire. It's a real pain in the ass to lug around lead-acid batteries to and from a charger. And with four sensors, you might have to do that frequently.
For the wireless part of the system, you can buy four of these for the transmitters:
http://www.sparkfun.com/products/10534
And one of these for the receiver:
http://www.sparkfun.com/products/10532
I'm trying to think of a quick and easy way to interface to the receiver, but sadly nothing comes to mind. The easiest way would seem to be an Arduino, and that isn't as easy as I feel like this should be.
Still, pretty hard to beat the price. Four sensors @$20 => $80 + 4 transmitters @$4 => $20 + 1 receiver @$5 totals out to $105.
The major cost is in the beam sensors. You can make those yourself too if you like, but you'll need some non-trivial electronics skill to do so. It's mostly some IR LEDs to create the beam, a photocell/phototransistor to receive the beam, and a schmitt trigger to monitor the output of the photosensor but avoid noise and false alarms. Because you're only going to be making 4 or 5, the cost per unit may be higher than one would expect. Still, I expect you could make them for less than $20 each. (Not sure how much less...)
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If putting the whole system together yourself is annoying, or you're short on time, you can of course spend more money and buy a pre-made system. But the cost is high, especially for 4+ sensors.
For example, take http://www.entryalertproducts.com/site/1313934/product/00-200
By my reckoning, a 4 beam system will cost $190 (base unit + 1 tripbeam sensor/transmitter) + 3 * ($70 tripbeam + $50 transmitter) = $550.
Gotta love the X-10... however I've found those sensors to be....frustrating, to put it nicely.
You might try something like this wired into this (if you can find one)..Thinking alone the lines of a few well placed mirrors, some beers and plenty of cursing, you could make "tripwires" for the animals, rig up a delay on turning it off, and voila. No more random ropelights as you walk on the deck.