low temp snap action temp switch needed

[Albert]

I need a bi-metallic switch, automatically resettable that closes
around 15F. A small inexpensive type, similar to the kind put inside
nicad battery packs to limit the dissipation of the batteries would be
ideal.

What I'm finding when I google is very large and expensive temperature
controllers that operate from 60F and up.

Anyone know of vendors selling these types of products???

What I want is a simple alarm to warn me when my freezer gets too warm
to keep the contents frozen.

Thanks.

A

 

[NSM]

<Albert> wrote in message | I need a bi-metallic switch, automatically resettable that closes
| around 15F. A small inexpensive type, similar to the kind put inside
| nicad battery packs to limit the dissipation of the batteries would be
| ideal.

Search for Klixon:-

Preset temperatures from -65°F to +550°F
Ratings: dry circuit to 15 Amps, 30 VDC or 120 VAC

| What I'm finding when I google is very large and expensive temperature
| controllers that operate from 60F and up.
|
| Anyone know of vendors selling these types of products???
|
| What I want is a simple alarm to warn me when my freezer gets too warm
| to keep the contents frozen.

Look in your local libraries for back copies of electronics magazines.
You'll find simple designs which are better than a snap switch.

NM

 

[Pooh Bear]

I need a bi-metallic switch, automatically resettable that closes
around 15F. A small inexpensive type, similar to the kind put inside
nicad battery packs to limit the dissipation of the batteries would be
ideal.

What I'm finding when I google is very large and expensive temperature
controllers that operate from 60F and up.

Anyone know of vendors selling these types of products???

Yup - ppl like Microtherm IIRC

I've never seen a low temp version though. Usually ppl are worried about *overheating*.

What I want is a simple alarm to warn me when my freezer gets too warm
to keep the contents frozen.

Are you using active electronics ? Considered monitoring the Vbe of a transistor
junction ? That works well. Not as simple as a switch though.


Graham

 

[Asimov]

"Albert" bravely wrote to "All" (13 Nov 04 17:20:03)
--- on the heady topic of "low temp snap action temp switch needed"

Al> From: Albert <>
Al> I need a bi-metallic switch, automatically resettable that closes
Al> around 15F. A small inexpensive type, similar to the kind put inside
Al> nicad battery packs to limit the dissipation of the batteries would be
Al> ideal.

Al> What I'm finding when I google is very large and expensive temperature
Al> controllers that operate from 60F and up.

Al> Anyone know of vendors selling these types of products???

Al> What I want is a simple alarm to warn me when my freezer gets too warm
Al> to keep the contents frozen.

Al> Thanks.

Al> A

Find a discarded freezer and rip the thermostat out of it. Use this to
sound an alarm powered by battery. Set it a little higher than the one
in the present freezer.

A*s*i*m*o*v

.... A fail-safe circuit will destroy others.

 

[Joerg]

Hi Albert,

Look for "frost protection". A friend has a pipe heating loop between his house and well in Sweden. I believe the thermostat was small and adjustable but it would close (not open) when the temp goes below a certain level. He told me they are set 'by experience'. People out there know how low temps can get below freezing before this electric heater line has to come on for a buried line.

Regards, Joerg