Automatic Hen House Door Closer Opener
Automatic Hen House Door Closer Opener
Find out how to put together a DIY automatic hen house door opener and closer
electric circuit | general | solarAn automatic
hen house door opener and closer is very useful for anyone who keeps
hens and cannot guarantee they'll be able to manually open or close the door every day. Simple systems have a
light detector and the door is opened at dawn and closed at dusk. More advanced systems have a
programmable timer which in most cases is preferable since you can then set it to open the door later in the morning if the (free range) hens are laying eggs all over the place, or if you want to stop a cockerel waking up the neighbours early in the morning!
Retail hen house door openers / closers retail at
over £100, so the
DIY option is well worth considering. Many people have managed to put something suitable together typically using a
windscreen wiper motor or an electric car aerial to lift and lower the door, but then hit on the problem of how to
reverse the polarity of the motor so that the door can be opened AND closed.
Simple
DC motors such as windscreen wiper motors (pictured above) will rotate forwards (clockwise) with the + and - leads connected with the correct polarity, and rotate backwards (counter-clockwise) with the power leads reversed. This is perfect for this type of application since we want the motor to spin one way in the morning to open the door, and then the other way to close the door.
It is not until you actually take a couple of
relays and a motor and you try to wire them up so that if relay 1 is energised the motor spins forwards, and if relay 2 is energised the motor spins backwards, that you discover that everything is not quite as simple as you might imagine. It is
very easy to end up causing a potentially dangerous
short circuit at worst, or for the system to just not work at best.
In the rest of this article we will focus on one method of getting around the problem of reversing the polarity of a motor using two relays.
Reversing the Polarity of a Motor with Two Relays
Above is shown a schematic diagram using a couple of
SPDT (single pole double throw) relays. As presented above, neither relay is energised (as will be the case the vast majority of the time) and the motor will not turn since both power inputs are connected to V+. Similarly, if both relays are energised (eroneously), the motor will also not turn since both power inputs are connected to 0V as shown below.
However, if
just one of the two relays is energised, the motor will spin, with the
direction of rotation depending on which relay is energised. Below, if just relay B is energised the motor will be connected with the correct polarity and so will spin clockwise:
...alternatively if just relay A is energised, the motor is connected with reverse polarity, and so spins anti-clockwise:
It is common to connect a small capacitor (e.g. 10nF) and a resistor (e.g. 100 Ohms) in series across the DC motor to protect the relays from the high voltage pulse released when the motor stops spinning.
With everything connected as shown above, all that remains is to connect the motor to a pulley which will pull up the door in the morning, and lower it in the evening, and an electronic controller to manage everything. Such a system is
ideally suited to be powered with a
photovoltaic solar panel since very little power is drawn on average through the day since the motor is used for just a few second twice per day. A small solar panel (1-3 Watts) and 12V battery will be more than adequate, and could also be integrated with a
Poultry Lighting System during the darker months to promote frequent laying.
Buy a Hen House Door Controller
If you are interested in purchasing a 12VDC controller circuit board including two relays wired as above please email
neil@reuk.co.uk. You can choose between a
modified programmable digital timer which will open the door at a fixed time every morning, and then close it X hours later, or a more basic (and of course cheaper) circuit with a light detector which will open the door at dawn and close it again at dusk. All we need to know is how long you need to run the motor to fully open the door, and how long to fully close it again. Prices start from around
£25.
Click here to purchase a used or new
windscreen wiper motor from
ebay UK for as little as
£0.99. It is also possible to purchase complete
automatic hen house door systems there for around £100.
Article Last Modified: 11:47, 27th Jun 2009Comment on this Article
If you have any comments on this article, please email them to
neil@reuk.co.uk.
My chicken shed door works really well. Managed to do it with old car shock absorber (as a ram), 12V compressor (£6 from Halfords), and using one timer with two headlamp relays and two car door light switches (to de-power relays when door fully open or closed). Uses minimal power.
Andrew, 19th August 2009 |
Recommended Related Articles
People who read this article also enjoyed the following articles:
PIR Sensor CircuitsFind out more about using PIR sensors within renewable energy applications
Article Last Modified: 11:32, 3rd Nov 2007electronics | electric circuit | general | solar12 Volt Programmable Timer SwitchAutomatically control devices with a 12 Volt powered timer switch
Article Last Modified: 13:26, 7th Aug 2008electronics | lighting | generalRepeat Timer CircuitMake a repeat timer circuit with large intervals between ON times
Article Last Modified: 09:58, 15th Aug 2009electric circuit | electronics | generalTimer Circuits With 4060BBuild a reliable timer to switch devices on and off - from 30 seconds to 24 hours
Article Last Modified: 09:58, 15th Aug 2009electronics | electric circuitLM741 Light Dark Sensor CircuitBuild a light/dark sensing circuit to automatically turn on/off lights and other devices
Article Last Modified: 08:43, 2nd Nov 2007electronics | electric circuit | generalMotion Sensor Light SwitchFit a motion sensor light switch to automatically switch off lights when a room is empty
Article Last Modified: 13:21, 31st May 2008lighting | energy efficiency | shoppingBattery DesulfationFind out how to desulfate/desulphate and rejuvenate lead acid batteries
Article Last Modified: 16:56, 5th Oct 2009storage | electronicsSolar Charge ControllerFind out more about Solar Charge Controllers
Article Last Modified: 11:12, 29th Oct 2009solar | electronics | electric circuitREUK Poultry Lighting SystemBuy the tried and tested REUK poultry lighting system
Article Last Modified: 15:17, 28th Sep 2009solar | shopping | generalLight Dependent ResistorFind out more about LDRs and their use in renewable energy projects
Article Last Modified: 09:26, 24th Oct 2007electric circuit | solar
|
|
|
