PM FAO Zeity: Making a freezer door alarm

**Contreras** · 28 October 2014, 23:35

Originally posted by d000hg View Post

Our lodger keeps leaving the fridge and freezer door open and it's annoying having to defrost things all the time, find puddles on the floor, etc.

I found some products online which sound an alarm if the temperature rises, and I found some magnetic door alarms, but neither seems suitable... I either want an alarm which goes off when the door has been open some length of time, or one which goes off all the time the door is open but has an adjustable volume. e.g. this works perfectly but 130dB the whole time the fridge is open would be rather wearing

So I thought about dusting off my schoolboy electronics - a cell in series with a light and/or buzzer with some sort of contacts - but I've no idea where to buy the parts. Where to look and any tips?

edit: here's one idea: Fridge Door Detector Alarm
Although I was thinking about fitting it externally with some sort of contacts like on door/window alarms.

Fridge Door Alarm

ORP12 LDR. Google that for more ideas.

This one is obviously the deluxe version needing *two* 555 timer ICs (could be substituted with a single package 556 IC).

Will leave it to Zeity to explain how it all works.

**xoggoth** · 31 October 2014, 18:08

If you want to hear it outside kitchen, make it remote. Also you can bung it in a cupboard if it's too loud.

Get one of those cheap radio doorbells from Homebase, about 11 quid, and:

a) Rig it mechanically somehow so an open door presses the bell push. Will have to be outside the metal part of the fridge or you will lose the signal. Or better:

b) Use a switch or relay to operate it. Take the back off the bellpush (as you have to anyway to connect the battery) and you'll see the centre switch has four solder contacts. Connecting left or right pair rings the bell.

I recently added extenders to my normal wired door bell by using a small transistor as a relay. Now I can go down the garden and take the bell with me if I'm expecting someone. At least 60ft range.

**d000hg** · 3 November 2014, 08:46

I don't think a remote alarm is what's needed - more an audible but not too loud reminder that the door is open. So you can get the milk out without it waking people up but you are aware you haven't shut it properly.

The timer part is optional really. I was thinking an external system is better where the door being closed pushes some sort of switch to the off position (like the light in the fridge) because then even I can make that circuit if I can find such a switch... switch, light, buzzer and cell in series.

However a little timer would be nice. I wondered if one could add a capacitor to the circuit to achieve this, or whether you can just buy a push switch which has some sort of mechanical delay built in (i.e. a damped spring or something) so that it doesn't actually close the switch for a few seconds.

**RSoles** · 3 November 2014, 19:43

Or an Aduino with a cellular shield to text the lodger to shut the @@@@@@@ fridge.

Actually, you don't need an alarm, just a baseball bat.

**TykeMerc** · 3 November 2014, 23:03

Just fit a basic door closer to the fridge......

Or a FOGB label on the door SHUT THE FARKING DOOR, WERE YOU BORN IN A BARN YOU TIT? might do it.

**d000hg** · 3 November 2014, 23:26

Originally posted by TykeMerc View Post

Just fit a basic door closer to the fridge......

Or a FOGB label on the door SHUT THE FARKING DOOR, WERE YOU BORN IN A BARN YOU TIT? might do it.

Tried that. Only works if the person is looking at what they're doing, not in some sort of day-dream.

A door closer?

**Contreras** · 3 November 2014, 23:58

**Contreras** · 4 November 2014, 00:12

Dane Petersen (thegreatsuna) | Adaptive Path Fridge Alarm

And there's more...

Faz Jaxton » Fridge Door Alarm – 555 Contest Entry

PM FAO Zeity: Making a freezer door alarm