Cat door opener project newbie

I am pretty new to arduino so keep that in mind. I got this video from youtube and put everything together but for a cat door not a bin HOW TO MAKE SMART DUSTBIN USING ARDUINO, ULTRASONIC SENSOR & SERVO MOTOR || ARDUINO PROJECT - YouTube .
My issue is the motor mentioned in this video is not strong enough and i replaced with a stronger one(BMS-630OMG) as thats what someone gave me. I do have the servo motor that goes with this project. I can upload a picture of the setup. Was quite a feat to do. Ofcourse i tested it with the weaker servo and it didnt lift the door. Is there something in the code of the youtube video that i am supposed to adjust? I am not used to arduino code yet but have edited codes in website building etc

How are you powering your project?
Not using a 9V battery, like the idiot who posted the video, I hope.

Aren’t cats sensitive to ultrasonic sounds?

The video is a decent (I wouldn't say good) introduction to a practical servo project. You learn the basics.

The 9V battery is OK for table top experiments, but in this video, I suspect that the battery has to be replaced daily.

If you have the mechanics worked out, but the servo isn't strong enough to move the door then you need a larger servo motor. The one in the video looks like an SG90 which is fine for moving the control tabs on a model airplane, but the foamcore lid in the video is probably stretching the limits of 1.5kG per cm. The specs for the SG90 servo vary depending on who made it and who is selling it. Always go with the lowest spec claimed by the seller.

Most of us don't have a way to measure the weight that we're asking the servo to move, but this gives you an idea what the spec of 1.5kG per cm means.


The specs for the BMS-6300MG are impressive. They specify the torque at 146 Newtons per cm, which is roughly 15kg/cm. Probably enough to move the door.

One spec that you won't find for any servo is the max current, or stall current. But, this is important- the Arduino can only provide up to 40mA max.

The BMS-6300MG will surely need more current than the Arduino can provide. Trying to power the servo from an Arduino will likely end with a damaged Arduino. So, stop doing it now!

You may see this line in the forums a lot: The Arduino is NOT a power supply.

What this means is that high current loads like a motor or the BMS servo must get their power directly from a battery or power supply. Not from the Arduino.

In general, the servo should always be powered directly- not through the Arduino. (Though the SG90 is low-powered enough to power one from the Arduino).

Hope this helps.

Oh i forgot to mention i just plugged it into powerbank or was intending to plug into powerboard(using an adapter that you use for a mobile phone). Yes it was easy to follow. i have done some projects at a store called Jaycar. They were running workshops before covid hit. oh thanks for the info about a 9v ...doesnt sounds viable. yes i mean it tries to move but just not enough grunt in the little servo.
oh ok the person that gave me the more powerful servo seemed to know his stuff. he doesnt seem to want to help further tho. thanks for the advice. oh i didnt think of the arduino as a power supply. Oh i am not sure what you mean. oh i dont know know enough to figure that out. there was another youtube video that utilised a breadboard. is that what you mean? the breadboard version didnt work for me. or was the code wrong i dont know.

possible i am not sure

Lol no i used a powerbank but i had intended to get a longer usb cable and power it from a board

Please use quotes in your replies so that a casual reader has a clue what you are referring to.

The cat's hearing range is from approx. 50 Hz to 70 kHz! You hear a little less in the lower range than we do, but perceive much, much higher tones. So yes, cats can be sensitive to Ultrassonic, they definitely hear it. And I think, depending on the performance of the ultrasonic transmitter, cats will perceive this as noise, possibly even unbearable, so that they move away from an ultrasonic transmitter or try to avoid its proximity.

Why not just use the servo to move the lock on the door and let the cat do the opening?
I have a commercial door , that works off the chip in the cats Neck and releases a catch and the cat opens it - it’s cat specific .
The door has a coil around it to detect the chip .
If the door can open for any cat , you might as well let the cat push it open , you don’t need a mechanism .

Sorry i dont know how to do that on this forum

Oh ok i will see if she reacts. i have everything already and will see once i have it all happening

Yeah this is a cat that doesnt care. If she see's me she expects me to open the cat door or the human door. If she doesnt see me she doesnt use it. Too old to learn i guess lol. I tried treats and other things but local rats ate the treats. she is a neighbours cat and likes to visit only if i open the door lol. i wont be able to put anything in or on the cat.

Not necessarily. We once had two cats. I put a cat door in the garage door so they could go in/out. I showed both cats how to push open the door and go in/out. One immediately began to use the door. The other cat NEVER would use the door as long as she lived, no matter the weather.

You have to shove the cat through it a few times , very few don’t get it if they are hungry and it’s the route to food .
I certainly give it a good go before building something .
Well worth using a chip too - other cats will be in


You highlight the question then click on "Quote".

I worked on a cat door that was to be triggered by the cat's embedded RFID tag. I had some problems with finding a reader that would read the 134.2 kHz animal tags. All the cheap readers -- even the pretty good ID ones -- all are 125 kHz and don't seem to read the animal tags. I think the encoding is a little different in the animal tags vs cards and fobs -- I am not sure. In any event the readers seemed to cost more than a commercially designed cat door. I bought a PetSafe one thinking I could hack it.

Inside the PetSafe door, the reader part is not readily distinguishable from any of the other circuitry. It looks like the reader is all implemented in software in the same microcontroller that runs the rest of the functionality. On the plus side, the physical implementation looks pretty good. I wound up just extending the battery and motor control leads out of the casing so I could add separate battery level and operation count data uploads via 433Mhz radio.

oh thanks i worked it out.

yes the cat that lives upstairs is like that all except one door at another neighbours. but if she can see him through the door she waits til he see's her to expect him to open the door for her. with mine she wont even do that lol. she plays with me more than anyone so its weird. she is so used to me being available at her friends apartment that me newish cat door is not on her list of to do things. she does like to inspect my apartment though. if i am outside and near the door she moves to the door like 'ok now its time to let me in'. oh well hope someone here can tell me how to get this door opener happening

wish i could do something like that. This is not 'my' cat. she is a neighbour. the 'owner' is invested in self medication and the elderly man that mostly looks after her is getting super frail. i will most likely adopt her at some point. hoping i can get her to change her ways but cats are stubborn. they wont let me put a collar or anything on her. we had that issue some years ago. very complicated. its a pity you didnt get the device to work the way you wanted