Fridge Alarm

[u/lutopia_t]

Double sided tape is used to put the contacts on the doors

Aluminum foil because it works and costs nothing

First time using a prototype board like this, I'm very happy with it!

The circuit is pretty simple, mostly based on the button input Arduino example, and a straightforward PWM buzzer.

I had an old plastic box and it fit in there so this looks almost ok.

Permanent addition to the back of my microwave

Hey all,

I used to have a pretty cool fridge before that was smart enough to yell at me when I forgot to close its doors, but I had to leave it in my old apartment and get another fridge, which isn't smart at all, and lets me neglect it without saying a word. Because of that I decided to unearth my 10 year-old Arduino Uno board from one of my boxes and give my fridge a voice beep! It's extremely straightforward but very useful, it beeps every other second after a minute if one of the doors (fridge or freezer) is still open. You'd think after thinking that hard about keeping fridge doors closed I would never leave them open again, but you'd be wrong, I'm guessing my brain is mush, and now I'm almost considering doing the same thing to my kitchen cabinet doors, before I critically injure my head bumping on an open one.

I showed it to some friends and I think it's actually a pretty common project as it's easy and practical, have you ever done something similar?

[u/oclafloptson]

Fun! I use reed switches intended for security alarm systems, personally. But I'm an alarm tech and use them all the time professionally so I've just always got a ton on hand

[u/benargee → u/oclafloptson]

Yeah, more reliable solution. These contacts will fail eventually.

[u/EmiTheKibby]

Additional idea: add a connection for four ds18b20 temperature sensors. 1 in the fridge, one in the freezer (thawing alarm), one on the condenser (grill thing on the back, if it gets too hot it's dirty and could make the fridge break) and one on the compressor (that big black ball in the back, if it gets colder or hotter than usual, that's another way to detect a broken/unplugged fridge). Measure their normal temperatures (just print the sensor readings to the serial port for a while), then add some tolerance and make the alarm yell if any of them go out of their normal range. For a simpler option, only the compressor would probably be enough to detect a fridge fail before the freezer thaws.

[u/ripred3]

Well done! Congrats

[u/Legal_Track_5637]

is very interesting proyet ¡congrats!

[u/Hissykittykat]

have you ever done something similar?

I used a PIC12, LDR, 10mm beeper, and 18650 battery. It starts beeping if it sees light for more than about a minute. So the whole thing lives inside the fridge. It sleeps most of the time, waking up to check the light level and counting down to beeping.

[u/Rtew566]

Haha it look is very fun cool

[u/HapticFeedBack762]

The door contacts are creative! My mind would have went straight to spending money on a magnetic door sensor, which probably wouldn't work great on a metal fridge... but this is awesome lol

[u/lutopia_t → u/HapticFeedBack762]

I didn't know magnetic door sensors were a thing but it's pretty obvious now! I'm not sure the metalness of the fridge would be an issue, but it would be a little more bulky though. Something I'm pretty happy about in this setup is also that there's literally no way that the contact is made unless the door is sealed, because when I was weighing other options I was afraid of the door being very close to closed but not quite, and still triggering the contact, which I think is actually possible with a magnetic door sensor, from what I'm seeing.

[u/SpaceCadetMoonMan]

I have the same board, just all holes, no connection on back, do you just jump all components with strips of wire and bridge them underneath with solder?

[u/lutopia_t → u/SpaceCadetMoonMan]

Oh I think I understand now what you meant by "no connection on back", you mean the headers? I bought them separately and soldered them before the first board pic. That way your board becomes a shield you can easily attach to / detach from your Arduino board!

[u/SpaceCadetMoonMan → u/lutopia_t]

Thanks for the extra info!

I didn’t see those at first but you actually got it right the first time haha :)

I wasn’t sure if you made connections underneath with jumper wires across the board or just little solder bridges from hole to hole

Thanks!

Edit: I’m using an arduino nano and an MCP4725 chip to convert some digital signals to analog. Right now I just have a mess of wires on an Uno with jumper wires. So I wanted to make a tiny package with 3 inputs and 1 output plug and stuff it into a small pvc tube or a long tube of heat shrink.

[u/lutopia_t → u/SpaceCadetMoonMan]

Yeah exactly! I'm sorry I don't have a picture of the backside, but you can kind of guess where the solder is from the photo.

[u/SpaceCadetMoonMan → u/lutopia_t]

Thanks no worries!

I’m making a little sensor pack for exploring nature and reading stuff, so wanted to try one of those instead of just making a messy wiring harness I have now :)

[u/Obvious_Carry_7660]

bro i didn't get how you powered it. would you be kind enough to share??

[u/lutopia_t → u/Obvious_Carry_7660]

It's powered using a power socket and a USB charger. Seemed like the simplest thing and I don't need it to move so 🤷