Any Ideas How Make Freezer Warning Trigger an Intruder Alarm

[Contax]

I AM TRYING TO DO THIS.
When my freezer warning light comes on I want it to trigger a relay to open a pair of alarm contacts on wireless alarm, if I get a relay with 240v AC Coil can I wire it onto contacts at rear of warning light so when warning light comes on it will trigger relay & open volt free contacts to activate alarm, do I need any type of diodes or resisters in circuit on power to relay or just feed 240v AC straight into coil terminals, I am hoping the warning light is 240v will have to get panel off & test it (Vestfrost Chest Freezer) bungalow 60ft from garage with freezer & I have a small wireless alarm to do job. I have used relays on 12v DC for split charging & on alarms to trigger flood lights with no extra circuits, it's only way I can think to do it, circuit diagram shows a small alarm buzzer option wired in parallel with warning light on same cables, it is model with manual thermostat, any Refrigeration or Alarm Engineers out there that could help please.

 

[breezer]

as you say, you realy need to find out the inicator light voltage first.

you could also consider a light dependant resitor, it would have to be mounted / fixed ove r the warning light (its resistance changes acording to the amunt of light falling on it, but it may not be sensative enough.

a light sensative transsitor would be better.


in either case you will need to build a small circuit to amplify the signal

but it maeans it has no connection to your freezer.


put a frost stat in a plastic box and put that in your freezer, small cable to your radio contact

 

[JohnD]

I think the indicator light is the wrong trigger.

I think you want an alarm that tells you the freezer is getting too warm.

if the cause is e.g. someone's unplugged it, the light wil not come on.

I think you want a thermostat as trigger.

 

[Europlex]

Just Google 'Freezer Alarm' and take your pick and then adjust the output for your needs

 

[Contax]

I agree that a thermometer would be a better option to switch alarm contacts but I have searched google & ebay for weeks and only types are made for freezer banks in medical use or logging systems and very expensive, there is a unit for about a tenner that has a probe in freezer and on temperature rising to -9 degrees C it lights an LED & beeps every so often, ok for in home but my freezer 60ft away in garage, if I could buy a unit like that one that would open 2 alarm contacts it would be great. it is a Vestfrost and it has option of a small buzzer wired in parallel with red warning light on circuit diagram. It is an A+ class freezer so if power goes off food is sake for 46 hours , I have a digital thermometer fitted, I also have a warning device for mains power loss (an emergency light that is wired into same plug and is battery backed), the plug is at garage roof level with cable ties to stop plug being pulled by accident, my main worry is freezer malfunction. I am very gratefull for any ideas.

 

[breezer]

or like i said get a frost stat and put it in a box in the freezer, the kit listed starts at +5 degrees, too warm for a freezer, and too late

 

[JohnD]

I agree that a thermometer would be a better option to switch alarm contacts but I have searched google & ebay for weeks and only types are made for freezer banks in medical use or logging systems and very expensive, ... .

http://cgi.ebay.co.uk/FREEZER-THERM...ryZ71259QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

http://www.rapidonline.com/Electron...sors/Temperature-sensors/34461/kw/temperature

http://www.rapidonline.com/Electronic-Components/Sensors/Thermocouples-Thermistors

http://search.ebay.co.uk/search/search.dll?from=R40&_trksid=m37&satitle=freezer+thermostat

 

[Contax]

SORRY to Moderator for breaking Rule 5.
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I can't find anything on google or ebay unless I spend a fortune on types for hospitals and such, Cobolt Systems do one that triggers when temp rises to -9 C but switches on an LED and beeps 3 times a minute, uses one AAA battery, I don't know how to modify it to open a pair of contacts to trigger my wireless pager alarm, maybe easy for an electronics expert but I have no knowledge, so still searching.
Thanks for the ebay link for cheap thermostats, I bought 2 for freezer and 1 for fridge, total £6 less a £5 ebay voucher so only cost £1 the lot, worth keeping for spares, I might try one to see if it will do the job.
If anyone thinks of any thing I am still searching.

 

[breezer]

like i said, put a stat in a box, and puit it i the freezer, connect your radio contact to this (i hadn't thought of mains fail at the time)

 

[Contax]

I am not so worried about mains failure as power to garage comes from bungalow so I would know it was off (emergency light on front of garage woud come on as on same twin 13a socket) and would keep checking digital thermometer I have on freezer and if high connect to generator untils it cools again, my main concern is a fault on freezer that would not be noticed until I went 60ft to check it and find red warning light on, am alarm that omes on with red light would notify me before food went soft and I could move food to old spare freezer, I am in bed ill for a week at a time so no alarm and it could all be melted when I next check it. it seemed a simple project when I thought of it.

 

[Europlex]

I can't find anything on google

There are dozens to be found on Google, just adapt one. You were thinking of doing that with the mains light (dangerous) as mentioned in your first post