Simple thermometer, repair or rebuild? - Page 1
Forum section: electronics / beginners

author: fatunicorn
author_rank: Newbie
timestamp: August 10, 2019, 06:47:00 pm
content: Hello, I’m Simon and I’m new hereWe got a pack of Duracell AA batteries years ago and there was a simple digital thermometer shipped with it.My father liked it very much because it just showed the temperature with a big lcd display and was powered by a single AA Cell.But it fell on the floor and the display is now broken.I was looking around for something similar, but most thermometers have either those small battery cells (which are very overpriced here in Switzerland) or things like air humidity in the display, which we don’t need.Should I try to find some similar lcd screen to repair it or should I try to make my own?I have a little experience with Arduinos, soldering and have access to a 3D printer.I've been thinking about replacing the battery with a supercap and a solar cell, but I don't think this would be enough for uninterruptible operation.A solar cell and a lithium battery may lead only to more complexity.Sticking to AA batteries would be the easiest solution, but I don’t have the know-how to do a project like this, especially for low energy consumption devices.Is it even a good Idea to use a microcontroller, or are there ICs which can handle this task better?Thank you very much for your answers

author: tunk
author_rank: Super Contributor
timestamp: August 10, 2019, 07:04:20 pm
content: Is this an alternative: Ikea has a clock/thermometer called klockis which uses two AAAs.And I would guess that an arduino eats batteries.

author: Wimberleytech
author_rank: Super Contributor
timestamp: August 10, 2019, 07:33:52 pm
content: Not sure what itch you are trying to scratch, but here is a simple solutionhttps://ebay.to/2YWxiTd

author: MosherIV
author_rank: Super Contributor
timestamp: August 10, 2019, 08:46:58 pm
content: Hi Simon.Welcome to the forum.I am affraid that repair maybe not be possible.As far as I know, the only commonly available lcd screen available are generally either 3 or 4 digit counter type or maybe for digital clocks.I do not think you will be able to easily find a replacement lcd screen for a thermometer.It is really not worth making your own thermometer unless it is for the learning experience.

author: ledtester
author_rank: Super Contributor
timestamp: August 11, 2019, 05:17:06 am
content: This one has fairly large digits:https://www.aliexpress.com/item/32997183403.htmlor have a look here and see if anything strikes your fancy:https://www.aliexpress.com/af/large-lcd-thermometer.html?SearchText=large+lcd+thermometer

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 05:57:41 am
content: If you can only find something powered by coin cells, it's easy to wire in a AA or AAA holder and use that instead. Or you can just buy a pack of coin cells from China which is what I do. They're very cheap online, you can buy a package of 100 of them for about the same price as buying just one in a store.

author: soldar
author_rank: Super Contributor
timestamp: August 11, 2019, 10:30:05 am
content: Quote from: james_s on August 11, 2019, 05:57:41 amI have been doing that for decades except I use AA or AAA batteries that can no longer power whatever device they were in. They can still power a thermometer, clock or other similar device for years. And I don't even bother with a battery holder, I just solder the cables directly to the battery.It seems I have several thermometers and clocks in each room. It seems I cannot get enough information. If I am asked what is the temperature I will ask in what part of the room because there can be substantial differences. And the same happens in the refrigerator. If you move the thermometer around you will see the great difference in temperature and know where to place the food according to the temperature you want.

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 07:12:03 pm
content: The reason I would be hesitant to use tired batteries like that is leakage, I never used to have that problem but in the last 10 years or so I've seen a huge increase in leakage of AA alkaline batteries, I've even had them leak while still new in the package.

author: soldar
author_rank: Super Contributor
timestamp: August 11, 2019, 11:08:15 pm
content: Quote from: james_s on August 11, 2019, 07:12:03 pmMaybe I've been lucky but I have never had a battery leak until it was 100% discharged and should have been changed long time ago. never had one leak if it had any charge left in it no matter how small.

author: james_s
author_rank: Super Contributor
timestamp: August 12, 2019, 03:39:38 am
content: You've either been lucky, or found a brand of battery that is better sealed. I've had two movements ruined in one of my wall clocks by batteries that were leaking while the clock was still running.

author: soldar
author_rank: Super Contributor
timestamp: August 12, 2019, 09:30:35 am
content: I guess I've been lucky because I do not use any specific brand and just use whatever I have at hand. I have a box with "like new" batteries and a box with "so-so" batteries which will work with this type of very low consumption devices. The only times I have found a battery that leaked was in finding some device I had not used in many years and the batteries were dead long ago. Other than that it's never happened to me.I am attaching photos of one of the devices I have at hand. If you look at the date on the battery you can see it expired in 2010 and yet it is still going strong. Alkaline batteries hold their charge very well after years of storage.