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Custom Temperature Activated LED required build help required for a COMPLETE novice....


Good morning all.

Hopefully this group can help with this as what I'm looking for is a HUGE request of somebody out there to try and mentor me through what I want to achieve as follows, bearing in mind that I have NEVER EVER built a circuit before....

Throughout the summer months I do displays/talks about reptiles at public events. These animals for the duration of the event are kept in Really Useful Boxes (aka RUBs) and i want to make sure that after experiencing a few very hot days this year that the safety of my animals is enhanced with regard to them not overheating whilst in the RUBS (yes there are air holes etc but some days the general air flow is that low that i don't think that is enough)

So I have thought about building some very small circuits that have a thermometer probe that could be put down through one of the air holes in the lids and if the temperature goes above say 30-32.5C then a red LED will come on. There are a few things that it needs to be able to do/have as follows....

- the circuit/battery to fit in a cube say 35mm*50mm in plan and no higher than say 25mm tall (anything much bigger and it will just be too much of a distraction of what the animal is inside).

- Have an a switch for on/off operation (in the future I was thinking of gluing a magnet to the underside of the RUB lid next to the air hole and then using that to activate a reed switch to turn on the circuit as well as hold the circuit cube in place....)

- once the circuit is on, a green LED will need to be on so we know the circuit is active and that the battery isn't flat (this can either be a static ON light of a flashing light would flashing help with battery life?)

- This would need to be powered by something as small as a single CR2032 coin battery or similar.

- the thermistor bead probe to be able to be about 75-100mm long so it can dangle down through the lid adequately.

- whilst for now if we can somehow hard fix the LED turning red at say 30-32.5C, a future option would be to have some sort of adjustable setting as different animals have different comfortably maximum temperatures they prefer...

... I think that's the list of needs for now I really really do appreciate that finding somebody who can help with not only the design of this board but to coach me through component purchase, the actual build etc it is a MASSIVE request but with the help of the many online circuit design software out there I have found while trying to figure this out, i would like to think that somebody is up for the challenge.

I hope to hear from some of you soon.

Go safe.

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