On Sep 21, 1:18*pm, Jim K wrote:
On Sep 21, 1:14 pm, Mike Barnes wrote:



Jethro :

Grrrr ... about 200 worth of food wasted ....

Does anyone know if you can get some sort of doohickey you can leave in
the freezer which will sound an alarm if the temperature rises ? I know
cold kills batteries, so have no idea how it could work.

You can buy them, e.g...

http://digitron.co.uk/product/10/wir...wireless-digit...

...but IMO a temperature sensor isn't the right solution for this
problem.

I made (this *is* uk.d-i-y) an alarm device that senses if the door is
left open, even slightly open, for more than a couple of minutes.

The sensor is a 2-way magnetic alarm switch. The magnet is sticky-padded
to the underside of the door at the opposite side from the hinge. The
switch is sticky-padded to the underside of the body of the fridge,
almost touching the magnet when the door is closed. Also there's an LED
indicator which is wired in series with the switch. The switch/LED is
connected to a control box, about the size of cigarette packet, stuffed
into the gap at the side of the fridge.

When the door opens, the switch closes, which lights the LED (to confirm
that it's working) and starts a timer. When the door closes properly,
the switch opens, the LED goes out, and the timer stops.

But if the door isn't closed properly, the LED stays lit, and the timer
sounds an alarm after a couple of minutes. Closing the door properly
cancels the alarm.

The whole thing is powered by a wall wart. I used a pre-built timer
module from Maplin or CPC (I forget which), which has a simple adjuster
for the timer delay.

Once installed, it's simple and effective.

--
Mike Barnes

neat! why dont they build em in FFS?

Jim K

Whirlpoo have them built in too. 30 seconds with door open, eg while
loading it up, and it starts bleeping. Close the door and it continues
bleeping for a few minutes more. And no, the cancel button doesnt. And
if the mains feed fails, well, there wont be any alarm. Oh well, I
guess it sounded like a good idea. In reality its a nuisance, and
since the door is well sprung it has close to no use. The only time it
would ever be of use is if the thermostat or comperssor failed. And
even then, few people will have spare freezer space in another machine
to use, or get a new machine delivered within hours.

So yes, theyre useful, but get the design details right or theyre
nothing but a stupid liability.


NT