G’day, this is hopefully something simple that my complete ignorance makes difficult, but I was trying to solve a problem for my sister instead of an expensive Xmas present (due to working in an industry incompatible with covid conditions)
She has irregular hours and wanted a way to let her chickens out when shes not onsite.
After thunking a bit, I considered a electromagnet locking a “drawbridge” in place, that could be switched ‘off’ (and open) by a programmable power board.
Is this even feasible? In my ignorance, is it harder than it seems?
I want to keep it fairly simple, but these things always seem to complicate themselves.
Can anyone help?
In general terms, you can do this with a timer, a solenoid, and a switch. The solenoid is simply something that has a part that moves when electric current passes through it, so could unlatch a gate. The timer will allow current to pass to the solenoid at a set time. The solenoid allows the gate to open. The switch is arranged so it is closed (passes current) when the gate is closed, and opens when the gate opens. It is between the timer and solenoid, so once the solenoid has done its job, the current is cut off. Some solenoids can only run for a second or two before they overheat, others can run continuously (like ones in washing machines that control the water). So it is a good idea to cut the power as soon as it isn’t needed. If the gate is closed in the evening when the timer is no longer activating the solenoid, the system is reset for the next day.
It would be very cheap and illegal to do this using a mains timer (from $6), a second hand solenoid from a washing machine (they work off 240V) and a suitable switch. However, this would require mains wiring - illegal and unsafe.
A safer solution is to use a low voltage plug pack on the mains timer, to run a 5Volt or 12V solenoid. Core have a 5V one for $8. If you want the gate latched closed when normally it would be open, you can unplug the pack so the solenoid is disabled regardless of the time. The plug pack doesn’t need to be fancy, just deliver the required current (a bit more than 1 Amp for the Core one, a 5V 2A would be plenty).
This assumes there is a place to plug a 240V timer in somewhere near the chook yard. Is that the case?
Plug the timer into the 240V power point and the plug pack into the timer. There are electromechanical ones around with 24hr timing and also electronic types with 1 week worth of programming.