[SOLVED] Noisy cat-flap solenoid

[d123]

I have a cat-flap (not currently in use, and I may not get to use it again for quite some time, so this is hardly urgent) activated by the identity microchip, it has a sensor so only the "registered" cats can come in. Otherwise you get food raid visits or nap stops by passing cats, or worse, which I do not want, so not interested in using a normal one.
The cat-flap is so noisy opening from outside it would scare me with my head underneath it, sounds like a guillotine (even the user manual says some cats may be scared by the noise - it's so loud anyone would be scared). We used it in one house where I could change the door and install the cat-flap, she'd go out but never came in through it, she tried a few times then gave up.

I think it is a solenoid that activates the latch by the sound of it, one day I would like to change this, if it doesn't mean destroying the cat-flap in the process.

Somebody suggested using a cassette motor some time ago, not sure this would work if the actual latch is a solenoid. Any suggestions for silencing this awful thing or replacing the solenoid with a less cat-unfriendly device?

 

[D.A.(Tony)Stewart]

passive 4 way door, may be an improvement **broken link removed**

 

[BradtheRad]

Somebody suggested using a cassette motor

The motor spins a screw. A nut travels on its threads. The nut is attached to the latch (either directly, or by levers, etc.).

It would require ingenious mechanical ability, to hook it all up so that the motor can operate the latch. The latch needs to move easily, if your motor is a low-power type as found in a cassette player.

You would connect the power supply to the the motor one way to open the latch. Power it the other way to close.

 

[Warpspeed]

How about a car door lock (or boot) actuator ?
The boot ones pull on a cable, so the actuator itself could be embedded in foam rubber and be made almost silent.

 

[d123]

Great, some ideas of how this thing works before possibly taking it apart someday helps.

I agree:

It would require ingenious mechanical ability

- don't think I'd do a great job of it unless it's quite simple to modify, have to be realistic here about skills and knowledge.

How about a car door lock (or boot) actuator ?

- That's interesting, they are really quiet to begin with, thinking of the difference between a car door lock and the small external plastic cat-flap latch.

The rubber foam idea sounds good, anything to silence the thing.

The cat-flap design is pretty good and a great idea, except for the noise on opening from outside. It's this:

https://www.sureflap.com/en-gb/pet-doors/microchip-cat-flap

Thanks for the suggestions and advice, much appreciated.

 

[d123]

...I was thinking, muscle wire could possibly be a silent way of pulling the little plastic latch down. I don't know much about muscle wire, just the very little I read a few months ago.

 

[D.A.(Tony)Stewart]

A swinging glass door can be latched with an electromagnet silently from any trigger device. Moving Magnet with fixed coil.

 

[d123]

Hi there,

i saw that muscle wire is silent, but can take a "long" time to cool back to original length, and seems to need an opposing force (even a rubber band) to return to start position, but it does look promising.

Do you mean similar to the way a reed switch works, and probably more similar to those electromagnets used to lift large/heavy blocks of metal?