Photoelectric controlled latch for chicken coop

Hi All,

I am a newbie, and would like your help.
I have searched far and wide for a solution for this problem and I reckon that there is a real opportunity of the person who can design the following:

In essence this is a mechanism to open a latch when the sun comes up! The mechanism must be powered by a 12v battery and this battery must incorporate a solar trickle charger mechanism.

I know from visitng many forums and during my time spent looking for such a device, that there exists an increasing number of people who are keeping chickens and a definite need exists for this item.

I have attached a very rough outline below.

I think you can simplify your idea a little:
--> the solar cell can be used as the light detector as well
--> the battery can be replaced by a capacitor (or 2)

A solarengine circuit comes to mind (**broken link removed**). This works with a small (cheap) solar panel charging a capacitor. When the capacitor voltage reaches a preset level, the motor/solenoid/etc. is turned on and the charge stored in the capacitor is dumped into the motor/etc. This repeat while there is any sun out. You could disable the repetition after a min or so, if you wanted to, by adding a few extra components.

battery montor and one shot

use the one shot (5 seconds) to turn on the solenoid.
a second one shot could be implemented to turn on a bell at dusk. condition the chickens that when the bell sounds, its time to get into the coop.
the battery monitor is a little overkill but very accurate.

MrDEB said:

...
a second one shot could be implemented to turn on a bell at dusk. condition the chickens that when the bell sounds, its time to get into the coop.
...

Click to expand...

Pavlov's Chicken?

MrDEB, you might want to check the triggering portion of the 'one-shot'

photo transistor gets light and trigger input goes low
is there something I missed?

MrDEB said:

photo transistor gets light and trigger input goes low
is there something I missed?

Click to expand...

That's what I thought. Won't the trigger input be pulled low all day though (and not actually provide a timed pulse out)?

one the trigger impulse goes low the 555 only outputs one pulse.
it triggers on a low going pulse if I recall.
**broken link removed**
the link has lots of circuit ideas (knowledge)

MrDEB said:

one the trigger impulse goes low the 555 only outputs one pulse.

Click to expand...

True, the output will output a single pulse, having a minimum period set by RC; but if the trigger input is held down for longer than 1.1RC, the output will be high for as long as the trigger is held low.

MrDEB said:

it triggers on a low going pulse if I recall.

Click to expand...

The output is _set_ high when the trigger is low, and _reset_ low when the threshold is high; trigger pin has precedence over the threshold pin however. Neither threshold or trigger pins are edge-triggered (both are level triggered).