backyard inventors unite!

Jack Rowe jackrowe at
Mon Oct 12 20:32:27 EDT 1998


Re: automatic chicken doors:

Infrared sensors, hoping a coyote or raccoon never stands in front of the
chicken door? Cheap timer and an over-sized solenoid that wouldn't mind
being in 'pull' mode the entire day (or even for an hour at dawn and dusk)?
I think Mr. Coyote and/or Ms. 'Coon could quite possibly figure out the
schedule pretty quickly. They are much smarter than we humans, and not
above poking about during daylight hours if a fat hen or juicy eggs are
involved. Latches to hold the door open and shut, solenoids on timers to
release the latches and then pull the door open or shut, and 3-way
push-pull switches in just the right places to turn the solenoids on and
off when the door is latched into its new position... a combination of
these will do it if you're mechanically-inclined. 

I find, with these complicated mechanical projects, that starting out
slightly insane is a great help, also, since you avoid making the
sometimes-painful transition from 'sane' to 'insane' during the actual
course of the project. Good to get the insanity thing out of the way as
early as possible, anyway. Tidily takes care of the whole 'Life doesn't
make sense' quandary, after which Life itself is MUCH easier. Sorry about
the stupid jokes... while the auto chicken door is a great idea (I travel a
lot), it's also a kind of humorous one in the visualization and it's got me

I'm really pretty sure Ms. Raccoon would figure that door out pretty fast,
too. Once, in fact, I saw a case where raccoons were taking chickens right
through 1-inch chicken wire, not even leaving blood or feathers. It was
quite a mystery for a long time. Turned out the raccoon in question was
almost 6 feet tall, had fully-opposable thumbs, walked upright on its back
legs and drove a Ford truck. Spoke pretty good English, and as it turns out
could cook a mighty fine fried chicken dinner, hush puppies and all!
Damndest thing.

Re: sun tracking:

There are two directions the sun moves in: 1) east to west (daily); and 2)
low-in-the-sky to high-in-the-sky (seasonally). What are you doing with the
sunlight? If you can create a collector that takes in sun from either end
(as a single parabolic curve (curved like part of a cylinder as opposed to
part of a bowl) with the collector running along the long axis at the focal
line, then if you set it to the sun's declination (degrees above horizon at
noon) it would work reasonably well for the middle 2/3 of the day or so.
Then you'd just have to change the declination every few days (most
frequently in spring and fall). If you're doing something fancier, hmmm.
You might succeed in adapting gas-filled greenhouse vent openers to push
and pull in coolish sunny weather, but in summer they'd probably just try
and stay open all the time, and vice-versa in winter. 

BTW, mechano-wizards, never pass a discarded washing machine without a
pliers and philips-head in back pocket... nice solenoids of varying power,
normally-open (stops current unless you push it) push-activated switches,
pretty capable medium-capacity pumps built to handle some dirt, and a water
valve that's great for drip systems (use only on GFCI protected circuits
since both water and 120 volts will be involved). A/C units have
normally-open thermostatically-controlled relay switches that close (pass
current) on temperature rise, adjustable in the room-temperature range.
Fridges have normally-closed (passes current unless you push it)
push-activated swithes, and normally-closed thermostatically-controlled
switches that open on temperature rise in the just-above-freezing range
(carry less juice than A/C relays). Dishwashers have small water valves and
pumps. Electric heaters have normally-closed thermostatically-controlled
switches that open (stop current) on temperature rise, adjustable in the
room-temperature range. For about $40 you can get (at HVAC supply houses)
new thermostaticaly-controlled switches that can be used either
normally-open OR normally-closed, or in fact can be wired to turn on a
heater at one temperature and turn on a fan at a higher temperature --
great for greenhouses or the chicken house in temperate climates.
GFCI-protected circuits are a VERY good idea on any homemade techno-gadgets
using 110 or 220 volts. Etc! 

Don't try this at home.


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