A Driving Instructor's Blog

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The Chillmax AirAlso applies to InstaChill, Chill Tower, and any cooling device that costs under £100 and gets flashed up while you’re browsing and which claims to just run ‘on water’.

I originally wrote this in the very hot summer of 2019, and each year it spikes. The 2022 spike is underway after the first few warmer periods.

I haven’t seen it yet this year, but last year there was a new JML advert for the InstaChill. It is a larger version of the ChillMax, and it costs a lot more, too. But it works in exactly the same way. However, there is no way I am going to test one of those.

Be aware that these devices do not work to anything like the levels claimed. The original article follows.

Early in July 2019, I saw the Chillmax Air advertised on TV in one of those shouty ads. Then, the same evening, I was shopping in Asda and saw it on display. I am an idiot for things like this, and bought it on impulse so I could test whether it worked or not.

As a chemist, I know that in order to cool a large space effectively you’re going to need something with a big fan and a special refrigerant. In practical terms, that means a fairly bulky device with a motor-driven compressor, a closed radiator for the refrigerant to pass through, a fan to suck air in and blow it across the radiator, and a wide exhaust pipe through the wall or window to get rid of the ‘removed heat’. In some cases, you also need to collect or drain the condensed water that comes out of the air as it cools. A typical proper air conditioner for a small or medium-sized room will be about the size of bedside cabinet. The Chillmax Air is not much bigger than six CD cases glued into a cube.

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If you’ve used a normal desk fan you will know that you only feel cooler if you’re sweating a bit. That’s because the fan evaporates your sweat as it pushes air over it, and that evaporation is accompanied by a small cooling effect – it’s called ‘evaporative cooling’. If you’re not sweating, you don’t feel the effect. Conversely, if the surrounding air is very humid, then no matter how powerful your fan is, you will feel little or no cooling because sweat can only evaporate if the air has capacity to hold additional moisture (I’ll explain that a bit more later, because it’s what determines whether the Chillmax is any good).

As an aside, many liquids exhibit the evaporative cooling effect. In the case of diethyl ether (the stuff they used to use as an anaesthetic), if you force it to evaporate very quickly you can even freeze water (if you do it properly). However, ether is both highly flammable and toxic, so apart from demonstrating it in the school lab (where I remember it from, partly due to the massive headache the fumes gave me), it doesn’t have much practical application these days. Early refrigerators used it, which was spectacularly dangerous.

The Chillmax Air uses the evaporative cooling effect of water, and this is much less than with ether – similar to sweat, in fact. The unit consists of a reservoir at the top, which you fill with normal tap water, and this drips down on to a radiator unit which has ten sideways-stacked fibre panels in it through which a fan blows air. The water evaporates from the fibre panels, and the evaporatively cooled air comes out through the front grille. According to the marketing spiel on the TV ads, you’d be forgiven for thinking you’re going to get frostbite if you sit too close. I knew this wasn’t going to happen, but I wanted to know just how effective the Chillmax was.

When I first set it up and turned it on, the first thing I noticed was that the fan is quite powerful, so you get a good flow of air directed at you – but note that that it’s only a 5″ computer fan, so it can’t beat a proper desk fan for air flow. The air did seem a little cooler compared with what my desk fan was blowing at me, but it also felt ‘softer’ – that’s very important, and I’ll explain later. But the big question was how much cooler was the exhaust air?

I fired up my trusty data logger and left it in front of my desk fan for 30 minutes for the control data. Then I moved it and suspended it in front of the Chillmax for the same period of time. This is what it recorded (the red line is where I moved it).

Chillmax - temperature log in hot and sticky conditionsThe ambient temperature where I ran the test was about 29ºC. The Chillmax brought this down by about 4ºC.

So, the Chillmax definitely cools the air that passes through it. Let’s work on the assumption that it would be able to get the same 4ºC drop no matter what the ambient temperature was. If your room is 38ºC, pulling it down to 34ºC still means it’s bloody hot. And also note that since the Chillmax is physically so small, the cooling is very localised – it won’t cool a room down, and you have to have it less than a metre from your face to feel anything.

Now, some people might be thinking that a 4ºC is better than nothing at all. And they’d be right if it was just a matter of temperature. But there’s more to it than that. I mentioned that the exhaust from the Chillmax felt ‘softer’. I knew what it was, but my data logger shows it in numbers.

These are is the data for relative humidity recorded at the same time as the temperature measurement, above (the red line is where I moved the logger). The humidity went up dramatically – a jump of about 30%RH.

Chillmax - RH log in hot and sticky conditionsAs I’ve already explained, the Chillmax works by evaporating water on fibrous panels by forcing air across them. That water has got to go somewhere, and in this case it comes out as vapour in the cooled air. In the right light, you can actually see it – it’s essentially fog. And just like when it’s foggy outside, and everywhere gets damp, this vapour can condense on surfaces. My data logger collected some and began to drip during the test, and I have since discovered that it also condenses on the front grille and can drip periodically, so you’d need to be careful what you had underneath it if you placed it on a shelf. The fan is quite powerful enough to project the drips forward slightly when they drop.

The ambient humidity in the room where I did the test was about 44%RH. The Chillmax sent that up to over 70%RH.

It’s this elevation of the humidity of the cooled air which really brings into question whether the Chillmax is worth the investment. You’re probably aware that you can have a hot summer day in the high 20s where it is pleasant and comfortable, but a cooler and overcast day might be horribly sticky – or muggy. That’s because of the humidity, or water vapour in the air.

The amount of water vapour that air can hold varies with the temperature. Once you reach the maximum, any extra vapour condenses out as a liquid – misted up windows, dampness, even drips and pools of moisture on window sills or under lamp posts. Cold air can only hold a small amount of moisture before condensation occurs, but hot air can carry much more (think ‘sauna’). Although ‘humidity’ technically refers to the amount of water in the air, the figure most people are referring to when they say it is relative humidity. This is the amount of moisture in the air expressed as a percentage of the maximum amount it could hold at that temperature, hence the units %RH. It’s a very complicated subject, but the important factor for us here is that when it is warm or hot, higher relative humidity is uncomfortable. Indeed, you may have seen weather forecasts where they give the actual temperature and the ‘feels like’ equivalent – that’s a reference to the ‘Heat Index’, which takes into account the effect of the %RH. Here’s a graphical chart for that.

Heat Index - graphical representationAs an example, if the air temperature is 30ºC and 50%RH, it will feel like 31ºC, but if the humidity goes up to 80%RH, then it will feel like 38ºC – even though the thermometer still tells you it’s 30ºC.

Another example. If the air temperature is 35ºC, at 50%RH it will feel like 41ºC, but send the humidity up to 80%RH and it’ll feel like 57ºC – even though the thermometer still reads 35ºC.

The calculation for this is complex (you should see how long my Excel formula for it is). It is non-linear, and the increase in ‘feels like’ is greater at higher temperatures. It also contains an element of opinion/perception, which is why there’s no point using numbers above about 60ºC. But the ‘Heat Index’ is what forecasters use. Incidentally, the official health designations for the colours are: yellow – caution; amber – extreme caution; orange – danger; and red – extreme danger. Vulnerable people need to take these into consideration before going out in hot weather.

However, this is where the problems come in for the Chillmax and similar devices. If it’s 35ºC and 40%RH, it’ll feel like 37ºC. Cool the air to 31ºC but send the humidity up to 80%RH, and it’ll feel like 41ºC. So it’s actually hotter in terms of comfort. Do the same comparison when the surrounding temperature is 38ºC, and the ‘feels like’ goes from 43ºC to over 50ºC!

At lower temperatures the Chillmax will produce a slight net cooling effect. But if the air temperature is above about 30ºC (and 50%RH) – which isn’t excessively hot or humid to start with – it’ll actually make you feel warmer. And if it is already humid outside, you’ll feel hotter still.

Proper air conditioners remove water from the air they cool. This removal of moisture is why the air from proper air conditioners feels crisp, as opposed to the ‘softness’ of moist air. The Chillmax does the opposite of normal A/Cs, and adds moisture.

Aesthetically speaking, the Chillmax is a cube – more or less – about 15cm along each side. There are two buttons on the top rear, one which changes the fan speed to one of three settings (or off), with a blue LED for each, and another button that turns the night light on or off. There’s a flap on the top front through which you add the water. The radiator system is a plastic-framed insert which you access by pulling the front grille out. It slots in and out easily. You can’t officially replace the fibre inserts in the radiator, but you can buy the whole radiator assembly from JML for £15. My only major gripe is the power cable. The jack plug that goes into the Chillmax is quite stubby and doesn’t go into the socket very far, so it is easy to dislodge it. However, the cable itself is quite long, and the  mains plug is a moulded UK type.

JML claims the Chillmax can run for up to 10 hours per fill, but this is likely on the lowest of the three fan speeds, since on top speed it runs out in less than three hours.  JML sells the humidification as a positive without relating it to the comfort relationship between temperature and %RH, but note what I said above. If you want to cool down in humid weather, it isn’t just the temperature that needs to come down.

Does it really work?

It does cool the air by a few degrees, so in that sense it works. However, it also sends the humidity up, and in most cases that actually makes you feel hotter and more uncomfortable. In that sense, it doesn’t work.

Will it cool more if I use ice water?

No. Evaporative coolers are not influenced significantly by the temperature of the water used in them. The temperature of the air that comes out depends on the temperature (and humidity) of the air going in, and the science of evaporation. Only this evaporation results in the cooling effect observed.

Will it cool more if I put the filter in the freezer?

It might – while you’re blowing air over ice. But once they defrost, which will happen in a few minutes in the temperatures you’ll likely be experiencing, then no. You’ll also have more condensate to deal with from the melted ice pouring out of the front grille.

You may see reviews on Amazon claiming that freezing the filters (or using ice cubes in the water tank) does give cooler air. Trust me – apart from what I just said about blowing air over ice, it doesn’t. Science is involved, and evaporative cooling doesn’t work like that.

Can I use it to cool my PC?

Someone found this article on the search term “jml chillmax air for pc cooling”. No. Blowing damp air into your PC would be dangerous, potentially expensive, and would only gain you 4ºC at best.

Can you get larger versions?

Until August 2021, the answer in relation to the ChillMax was no. However, I saw an advert (as shouty as usual) for the InstaChill tonight. Unlike the ChillMax, which is the size of a small table top radio, the InstaChill is the size of a bedside cabinet. And you can certainly get larger evaporative coolers from other manufacturers. The working principle is identical, except that the larger the surface area of water, and the greater the airflow over that water, then the greater will be the possible drop in temperature at the front end (and the more moisture being pumped out to increase the humidity). However, cooling effectiveness is influenced greatly by the RH of the air going in.

If the air is very dry, then a large evaporative cooler might be able to drop inlet air at 30ºC down by as much as 10ºC. However, if the inlet air is very humid, the temperature drop could be as little as 1ºC. In the UK, the realistic temperature drop you could expect on a non-humid day for a large cooler would be around 5-6ºC, but on a sticky day you’d only get about a 3ºC drop.

Suppliers of these devices say that they need good ventilation or extraction, and I would imagine that’s so the humid air can escape. If you’re evaporating more water to get better cooling on larger devices, you’re also producing a lot more water vapour, so the cooling effectiveness will decrease as the humidity rises unless you vent it somehow. Be careful if you read any of the reviews on these things – people may have noticed cooling in already cooler conditions, but trust me – if it’s very warm and humid, you will not notice any effect.

People say it works

Be careful when you read those one-line reviews. If you test it when it’s only 20ºC outside – as many of these people have – then yes, it blows noticeably cooler air at you. But science is involved, and at temperatures above about 28-30ºC you’ll actually feel hotter. The fact that it increases humidity is the key factor. Remember that the reason you even found this article was probably because it’s over 30ºC outside – the more above that it is, then the more hits I get.

So, does the Chillmax/InstaChill work?

They cool the inlet air by several degrees. But they send the humidity of that air up considerably, and this cancels out the benefits of the cooling effect when it is very hot. The ‘Heat Index’ is the key detail, as explained above. In the case of the InstaChill, it will add a lot more humidity than the ChillMax, and as I have explained and demonstrated, the ChillMax is bad enough when it comes to increasing the ‘feels like’ temperature.

Only the air being directed at you is cooler. Once that slightly cooler air has passed through warmer air, it’ll be close to ambient again. The device cannot cool down a room. It’s far too small for that.

Humidity can carry much further, though. So in a small room, you could easily increase the ‘ambient’ RH without any cooling at all, and that will make it feel even hotter. If it is already hot, the amount of water vapour the air can hold before reaching 100% RH will be substantial. The increased humidity of the outlet air does produce localised condensation, so you have to be careful to keep these devices away from electrical sockets where they might drip on them. They also contain a significant volume of water when full, so you don’t want to knock them over.

Should I buy one?

My advice is to buy a proper air conditioner (A/C). If anything costs under £200 it is not a proper A/C. However, it is possible some people might find the minor cooling effect and increased humidity of the Chillmax/InstaChill (and similar devices) beneficial, so the choice is yours. But for real cooling and dehumidification when it is hot, it has to be a proper A/C.


OK. It looks like I’m going to have to wait until Autumn to replace the camera. We were back online for about a week, then the camera stopped streaming properly. It appears to be broken, though I can see it on the local network. However, I will be able to produce clips from my recorded files.

In the meantime, we have chicks! All of the eggs have hatched.

The resident bird damaged the aerial on the original WiFi camera while roosting in there over the winter (she’d actually torn it off). So rather than risk that again I decide to go for a fully wired system, and that took a little time to install. It would probably have been quicker if I’d have got off my backside and done it, instead of just thinking about doing it, but what the hey.

In the end I was lucky. I put the new camera in precisely one week before we noticed a lot of twigs under the box. It took another several weeks for me to get round to running cables and drilling holes in the shed and garage, and finally draping cables I have yet to fix properly.

Watch this space (and the updates below).


30 March – Early this morning she deposited her first egg. Apparently, they lay one egg a day (more or less) for about two weeks up to around 10-12 eggs, then start to incubate them. While they are laying, they spend all day outside eating because each egg takes a lot of energy to produce (it weighs about 20% of the parent), then roost with it at night. The eggs remain viable unless they freeze.

31 March – A second egg laid. She comes in to roost around 6pm-ish each night. The male must be sleeping somewhere else.

1 April – Now, a third egg.

2 April – Four eggs. Bear with me while I sort out the stream above. I can see everything on my home network, but I was fiddling and have broken something in the software!

3 April – A fifth. And she came back in at about 8am and covered them all up, which suggests that might be the last one.

4 April – No. Now we have a sixth. She is visiting the box more frequently during the day.

5 April – Now, a seventh egg. She’s been in and out all day with fluffy stuff to create the nest bed.

6 April – We have an eighth egg. She is has been incubating them, so I guess that one was the last.

7 April – No. One more. We have nine eggs now.

8 April – She’s now incubating them and the male has been in for the first time to ‘feed’ her. He’s not very good at it yet.

9-13 April – Not a lot of drama right now. The male only came in that one time, and I am assuming (from what I have read) that his work begins properly when the chicks hatch. The female spends over 80% of her time on the eggs, going out occasionally for a short while presumably to feed. She turns them over frequently during the day.

I have a mealworm feeder on order which I will put up away from the nest box to try and help her.

14-19 April – I’m expecting the eggs to start hatching anytime now. She pops out for a few minutes to feed – and she is using the mealworm feeder I set up on the tree about 5m away from the box – and then comes in to incubate. Periodically, she turns the eggs.

21 April – At around 3.20pm the eggs started to hatch.

22 April – And I was able to confirm that at the moment we have nine chicks, so all the eggs hatched.

Incidentally, I always wondered where the egg shells went after birds hatch. The mother eats them immediately (certainly in the case of Great Tits, anyway). And the male is now coming in regularly with grubs and caterpillars. He feeds the chicks himself sometimes, though he also passes food to the female and she feeds them.

29 April – I wondered what happens to the poop the chicks produce. Given that the they’re being fed huge grubs and insects throughout the day, there must be a lot of it. This is why there is a a clean nest, and it is fascinating to watch.

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I’ve been having problems with my birdbox camera. I’ve been having problems with my Ring doorbell. I’ve also been playing around with various CCTV cameras.

I’ll get on to the birdbox issue in a moment, since it is the primary subject of this article. But for general background:

  • my Ring Doorbell issue is to do with the fact that Ring is discontinuing the desktop app, which I can access instantly from my PC when I receive a proximity alert or a doorbell push to see who is there. Ring’s intended alternative is a web-based approach, which is slow, and which also requires you to log in via 2FA if you’re inactive for more than a few minutes – and by the time you have, whoever there is gone. So I formulated the idea of building my own video doorbell.
  • my CCTV interest developed from the Ring issue, and from learning a heck of a lot about IP camera networking from my birdbox camera, which gave me ideas for a home CCTV system.

Let’s not worry about how these all fit together in the history timeline of my mind, because I’m not sure myself! Right now, my birdbox camera is my main focus.

I installed a birdbox last year, fitted with a Wi-Fi HD camera. After some messing around to get a decent Wi-Fi signal to the end of the garden it worked brilliantly, and I got a night time resident roosting Great Tit within days of me putting it up. I had high hopes of a nesting situation come the Spring. Whenever the bird came in (and I will now refer to it as ‘she’, which will make sense shortly), she would often jump up behind the camera to pick off insects. That was no problem until the one time she did it and the signal disappeared, because she’d pulled the Wi-Fi antenna off the top of the camera.

I didn’t want to risk another Wi-Fi camera – my relationship with Wi-Fi is quite rocky at the best of times, and having a small bird disable it just added to that – so I decided to fit a wired one. After I’d put it in and run the network cables and PoE switches to the house, I had the video feed back. And as I’d noticed a lot of small twigs underneath the birdbox by the time I did that, I discovered she’d built a nest (when roosting over winter, she just settled on to the wooden floor). I was able to see the camera feed on my home network, and also able to stream the RTSP feed to the blog (and anyone else) so they could watch it live. It worked for about a week, and then the RTSP feed was lost – possibly a result of updating the camera firmware, or maybe because of a camera fault. I’m still pushing that side of things with the supplier, but at least I still have live access on my home network, as she has now laid eight eggs and is incubating them.

The problems with the camera set me off on my usual thought process, which amounts to this: well, OK. I can buy another one of those. But what if I made one myself?

In the case of a camera, and if it were based on something I had programmed myself, I would have full control over operation and repair. But what about the size of it? Those off-the-shelf birdbox cameras measure about 40mm x 40mm x 23mm, so there’s no benefit in building one the size of a refrigerator. But the Raspberry Pi Zero (a full computer) measures about 65mm x 35mm x 2mm, and a HD camera for it is even smaller, though it adds maybe another 5mm to the overall thickness. And I’ll cover this later, but a suitable add-on which gives PoE and wired networking capability adds a further 30mm to the thickness, so hardware-wise you could have a camera system which is only 65mm x 35mm x 40mm, and in a case perhaps 75mm x 80mm x 57mm (I already have one identified). That would fit in the birdbox easily and also give internal room for cables. The only issue from then on would be software.

The beauty of the Raspberry Pi is that people out there have already done brilliant things, and the software they produce is usually available for free. And software for creating ONVIF camera applications does exist.

However, many of those solutions have too wide a scope. In my case, I just want a raw ONVIF camera with no frills (other than a microphone, which might be problematic on a Pi), so I can get the fastest and highest quality image, then monitor it using Surveillance Station on my NAS. I can fiddle with motion detection – if I actually need it in my birdbox – within Surveillance Station. My approach is to keep things simple, and then build on that if I want bells and whistles later. But the DIY projects online try to put all the bells and whistles in right at the start, and many are likely to be superfluous to most people. Motion detection within the camera, which is one such popular feature, ramps up the processing overhead immediately.

This project will be similar to the Kneeling Chair one I did some years ago. I will add instalments as I go along. But right now I have several of these – the Pi Zero, cost £13.50:


One of these – the PoE HAT, cost £22:


I have this on notify for when it becomes available – it’s an autofocus HD camera for the Pi (though the actual one I end up using might change), cost £23:


And this is the case I am likely to use, which all of the above will easily fit into – cost £25:


Obviously, I will need a few more bits and pieces – some of which I already have – and I haven’t mentioned IR Cut for night vision at this stage. However, I will detail those as I go along. And the worst part is always getting the finished product – building an ONVIF device will be relatively easy, but mounting it compactly in the case so it can be used in a practical setting will be the hardest task of all, since I will have to drill that case and then make sure it is still at least water resistant when I mount it Inside the birdbox. It won’t get wet in there, but it will be subjected to variations in temperature and humidity.

Update: Hold on. I just had another idea for the birdbox camera issue. I have discovered that even though a typical CCTV camera looks like a Danish salami, most of the inside is empty space and the camera assembly is a section at the front.

I just tested one I have strapped to my second birdbox and it works. So if I disassemble it and re-package it into a suitable case, I will have a ready-to-use birdbox camera with all the bells and whistles of a CCTV camera.


DIY Doorbell Schematci LayoutA few years ago I bought a Ring video doorbell. After a bit of fiddling setting it up, it has worked reasonably well, though it isn’t perfect.

For a start off, it relies on Wi-Fi, which is a bloody nightmare at the best of times in the home environment. It is also totally dependant on Ring’s own cloud system (it isn’t an ONVIF camera, which I will go into later). But my main niggle is that I have no control over my data – and Ring is trying to make access to it even more difficult, thus enhancing the imperfections.

You see, the Ring system can currently be accessed via a desktop app, a smartphone app, or via a browser. I use the desktop app to monitor my system, because I can see absolutely no point in having a HD camera and only viewing it on a small smartphone screen. Furthermore, the smartphone app has a tendency to alert you up to a minute or more after an event has been triggered (I often get in my car and drive off from my house, only to have my phone vibrate when I get to the end of the road informing me I left a short while ago). And the browser interface has two-factor authentication and logs you out every five minutes, so if you get an alert, it can take some seconds to log in, by which time whoever was at the door has left. The desktop app is always connected (albeit with a tendency to decide not to give a live feed after it has been triggered). And another niggle is that the system only records several seconds of footage when an event occurs – it doesn’t record continuously.

But a couple of months ago, Ring unilaterally announced it was discontinuing the desktop app – initially, in mid-October, and currently (following uproar across the community), in December.

As I said, the Ring doorbell and the Ring system are not perfect. It can be glitchy, and it could do things better (like record continuously). But it’s a million times better than just ‘ding-dong’’ when someone calls, especially when that someone knocks instead (which most seem to do). However, without the desktop app, the glitchiness factor increases in significance considerably – the variable time lags with the other two methods are simply not acceptable. And as the Ring is a subscription device, I was rather miffed at this drastic change.

Running in parallel with all this is a very relevant separate story. During the summer I installed a birdbox with a camera in it in my garden. Once I’d assembled it and powered it up, it was immediately visible on my home network. That’s because it is an IP camera, and it uses the ONVIF protocol (as I mentioned at the start, Ring doesn’t do that, and forces you to use its own cloud service). Being ONVIF also means I can stream the camera feed live. Admittedly, my birdbox camera is a Wi-Fi system in this case (it’s at the end of the garden, after all), but ONVIF cameras can be wireless or wired – it doesn’t matter, and they just have to be discoverable on your network, which the ONVIF protocol takes care of. Better still, with my NAS system – which has Surveillance Station software pre-installed – I can continuously record the footage. Obviously, there’s no point saving every minute of every day forever, so I have it set to automatically delete anything older than (in my case) two days. This gives me time to manually save any particular footage I want to keep. It has motion detection, and I can edit the zones I want to monitor (and edit detection sensitivity as necessary). And best of all, all the data belong to me, and they are free – no subscriptions of any kind.

You can probably see where this is heading. On the one hand, you have the Ring doorbell – which taps into your network, but which has to communicate with Ring’s own ring-fenced servers across the internet, and those have to communicate back across the internet (or by SMS) to send any messages. It doesn’t record continuously, and no internet (or no Ring cloud) means no functioning doorbell. On the other hand, you have an ONVIF camera, which doesn’t require an internet connection, just a local network, which records continuously, and which has virtually the same overall functionality as far as the camera is concerned (just not a bell push feature).

I mean, come on! Is there a DIY project here or what?

I discovered that you can build an ONVIF camera using the Raspberry Pi. You can get open source motion detection software specifically for the Pi (though my Surveillance Station software already has that). And you can include various event detection features – button presses, for example – in a multitude of different ways.

The schematic diagram at the top of this article shows what I am planning right now. I will have a camera system based on a Raspberry Pi Zero with a bell-push button on the outside of my front door. This will connect to a hub, based on a Raspberry Pi 4, on the inside of the door (most likely, by a wired connection through the door jamb, but with Wi-Fi as a back up for the short distance of a couple of inches if necessary). The Pi 4 will be on the network, and almost certainly wired. Finally, I want two remote alarm units (one upstairs, and one downstairs), and I haven’t decided yet whether these will be wired or wireless – a lot comes down to how prepared I am to lay network cables, and the routes I could take if I did. I also haven’t decided whether to control them from the Pi4 or via the network. These remote alarms will be audio-visual – they will chime and flash.

If anyone is thinking I will end up with something the size of a fridge on my front door, just bear in mind the Pi Zero is 30mm x 65mm x 13mm in size. Camera modules are smaller, though the lens adds height. What I have in mind will certainly look different to a Ring doorbell, but it will be of a similar overall size if I assemble it  in an appropriate way. And a Pi 4 is only 57mm x 86mm x 11mm, so it will hardly be out of place if suitably enclosed behind the door.

This will be fun. Watch this space…

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I had my first non-insectoid and non-arachnoid visitor to my birdbox today. What appears to have been a Great Tit popped in and cased the joint.

He (or she) inspected every corner, and even checked the walls for integrity.

Apparently, this time of year they’re looking for places to roost, so I hope he comes back and then sticks around with a mate next Spring.

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