egg turner for an incubator

Someone may come up with something smarter, but I think you'll need a bistable element as well as that timer, from a quick look at my ancient RS catalogue.

The bistable element could be a toggle relay, one that changes it's output contact state every time the input coil pulses on. I have a beautiful old Omron with a 24VAC coil sitting on the shelf, if it'll assist you're welcome to it for nix, just email. The local kids will watch it in fascination for hours.

Wired so that motor is deenergised when either of the limit switches is active, ie. the egg thing is at either extremity.

Set your timer to generate regular short on pulses, say 10 seconds, separated by an hour (Asymmetric recycler mode if I read the book correctly). Use that pulse to pulse the toggle relay, to reverse the direction of the motor, and also to bypass the limit switch interlock. Thus for 10 seconds, the motor runs despite the limit switches, but in a direction that takes it away from the limit. By the time the pulse has finished, the limit switch is clear, so the motor will keep running until it hits the other switch, and stop.

Just another thought, if this really is for a poor Kenyan village, then this RS component is a bit of an odd choice. Way over engineered for the task at hand, and undoubtedly not cheap. Also, being electronic, it may not appreciate the sort of power supply it may have to put up with. I'm sure someone here will come up with something better.

snipped-for-privacy@weqstnet.com.au remove ecks and kyoo to email.

-- snip --

village, then

A poor Kenyan comes to mind.

Better ... no bistable relay required. Latch a normal relay on one limit switch, delatch it on the other one. Use a contact from that relay to control the motor direction.

Or have a couple village kids rotate the eggs by hand like the Amish do.

Eggs don't have to be turned back and forth. Rolling them works. Like in the old round metal Brower incubators. Can use a clock motor (hour hand).

Or, make some rollers the eggs rest on. Turn the rollors with a slow motor.

Most cheap incubators do rock the eggs back and forth, but use a unidirectional motor canged to bidirectional by the peg in groove mechanical part.

Make sure your thermostat can sold within 1 F, thats way more important. After 7 days or so, turning isn't even necessary anymore.

diode endswitch ------->|----/ -----| DC motor AC-----/ |------O----- AC --------|

A spatula?

Simpler than that: Use a SPDT limit switch, arranged so that when the egg roller reaches one limit, it flips the switch to the opposite contact. When the motor turns the other way, the limit switch remains as is until it reaches the opposite limit, then flip back. Use the following circuit: