Monday, 18 December 2017

Autogate: remote-control Gate

Autogate: control panel on far left. Note the swing-arm actuator anchored to the bottom of the gatepost

A couple of years ago, we had a remote-control gate installed. Known here as an autogate, it is quite popular, can be retro-fitted and is and not too expensive. The parts are available here online.

It gave no trouble for a year or so, then all of a sudden it would open on its own. Things got a little fraught because at about the same time, the wife had rescued three street dogs, and they would get out and fight with about six other dogs up the road.

Naturally we rushed up the road to get them back in, but they figured we had come to fight the good fight, and not only routed the other dogs but were having a grand time chasing them down and were in no mood to come home.

I had the repairman in and he fixed it, but within a month it opened again. This time I had a different repairman in and he swapped out the controller board and the power transformer. Within six months a lightning bolt hit the gatepost and you guessed it: it opened the gate. Luckily a rainstorm followed and the dogs did not fancy getting wet so we were spared the dogfight.

So I thought it is about time I got up close and personal with that autogate.  It has two swing-arm actuators which was mounted to the bottom of the gates and anchored at the gateposts. When 12V DC was fed to it, it contracted to open the gate or extended to close it.

The controller board has a Microchip controller which operated the relays that powered the actuators. It has two inputs, which when shorted to 0V, opened both gates or just one gate.

Top right: autogate controller. Top left:12V transformer
Power was via a 12V transformer, which the controller board also rectified and generated the 12V for the actuator, 5V for the Microchip CPU and 13.8V DC to charge a 12V sealed lead acid backup battery.

Remote operation is via a separate radio receiver, which takes in 12-15V and when the transmitter buttons are activated will put out a low impedance on its two output lines. Match these lines to the inputs of the controller and you have an autogate system.

12Vdc Actuators

The controller board is RM250, the transformer RM25, the remote control module is RM100. The actuators are about RM250 apiece, depending on the stroke length. For less than RM1000 including labor, you can get an autogate fitted.

Wired up controller board

But what about the problems? The first cause were ants. There are loads of them all over the garden. I find them very useful - get an ant colony living in the roots of your tree and they will keep the termites from eating the tree alive from the ground up. A year after the autogate was up, we had a very wet rainy season. The ants got used to walking along the gates (they are normally shut anyway) to avoid the runoff rainwater.

The control panel was nice dry and warm: ideal way station for wet ants. Trouble is, sometimes they shorted the remote control outputs. A shorted remote is a 'gate open' signal. The first repairman did a warranty repair - he replaced the damaged controller board and sealed up the panel door with sealant.

When the problem recurred, the next repairman found the ants had returned via the air vents in the panel. This time he put in some mothballs and sealed the panel again. Things were fine until the lightning strike, which blew out the fuze and the battery charger circuit.

I got tired of calling autogate repairmen - they are nice people and have reasonable charges, but they are never on time. Their idea of an appointment is sometime within a week. Besides, it is about time the gate got permanently fixed. Or so I thought.

Autogate controllers: Super i (left) and S-1 (right)

Since the controller boards were cheap at RM190 or so I bought a couple. They are different makes but all work the same way. I did not really choose them - they are simply the same ones the repairmen used. I just swapped the boards out when there is a problem. After a while I found it was quite easy to repair them, so I ended up with four boards, two spare, one in service and one a parts carcass.

The wife found the solution the the lightning problem: she simply found the circuit breaker to the autogate panel and turned it off when a rainstorm looked likely. Over the years we developed a routine- the broadband, satellite TV, telephone and autogate got disconnected before a storm and reconnected after.

The last rainy season was so wet water went into the sealed-up panel anyway and soaked the transformer into a leaky sorry mess. This I solved by bagging up the replacement in a freezer bag before remounting it. For good measure I duct-taped a bin liner over the whole panel. Not pretty, but a green bin liner kind of disappeared into the hedge next to the panel.

Problems solved, right? Well, kind of. We finally trained the dogs not to rush out whenever the gates opened (actually each dog was convinced only after she got caught in a closing autogate). We soon learned it was easier not to stand by the gate when it was being opened- the dogs tended not to bolt. Unfortunately this meant operating the remotes right at the limit of their range. Even so it was tolerable until we had a record wet season this year.

Heavy rains soaked the ground year round, and the remotes range decreased a lot. Plus I had been messing about with bluetooth Microchip PIC18F14K50 controllers. The range was so good the webserver in the study could reach the bluetooth PIC18F14K50 at the gatepost!

It is time to upgrade a bluetooth-equipped PIC18F14K50 to output to the autogate controller. With a PHP script in the webserver (my WiFi extended a few meters beyond my gates) we can then use our smartphones as an autogate remote. This will also make it an IoT device. Since my bluetooth PIC already read analog inputs I might as well include a battery voltmeter function.

Stay tuned for the next post the IoT Autogate. Happy trails.

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