AAG 1-wire rain gauge (TAI-8575) circuit diagram

I’m not going to claim this is absolutely spot on as I’ve reverse-engineered it from the PCB traces which aren’t always easy to make out, but below is my best current idea of the circuit diagram for the PCB inside the AAG rain gauge. The board is labelled TAI-8575 and I assume that’s a part number for the entire thing, but it’s mostly based around the now-defunct Dallas DS2423 1-wire counter chip.

The terminals for the 1-wire bus are on the left. The terminals on the right are for an additional switch that might be used for testing.

I don’t understand the numbering of the resistors: there only appear to be three, for a start, and I can’t see the screen-printed label for the 1M resistor. U2 is, I believe, a three-pin surface-mount device that contains two Schottky diodes with a common cathode. I’d assume it’s there to protect the two potential power sources from reverse voltages.

It’s also odd that the Dallas rain gauge which may actually be what this design is based on (or vice-versa) doesn’t use the resistor bridge or transistor. Effectively the reed switch is just across Vbat and the two inputs on pins 5 and 6.

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The rain gauge dismantled

I’ve now got the rain gauge down and taken it apart. Possibly I’ve posted photos before, but this is what the guts of it look like:

After ungoo-ing the PCB, I’ve come up with a first approximation of the switching part of the circuit which I have drawn, in true engineering fashion, on the back of an envelope.

The reed switch fell apart as soon as I touched it, so that’s definitely one problem to sort. The fact that there’s a dead battery welded to the PCB isn’t that helpful either. I may clip that off and replace it with something more maintainable. There are perhaps some other things that could do with tidying up too. I’ll ponder on those. Meanwhile, as I have most of the circuit worked out (I think), perhaps I should finish the job and draw it properly.

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My rain gauge died again :(

A short while ago my AAG 1-wire rain gauge stopped telling me that rain had fallen at all. The 1-wire device still shows up in Linux and is readable, but the 1-wire counters never change. I’ve checked by dribbling water into the funnel from a jug and the buckets tip, but there’s still no change in the counters. The circuit for the system is quite simple as far as I recall, being little more than the 1-wire counter chip and a reed switch in a housing next to the buckets, with a magnet fixed to the buckets tripping the reed switch each time the bucket tips.

It could be a failure of the 1-wire chip, or (as I suspect is more likely to be the case) the magnet is not activating the reed switch for some reason, perhaps because it passes the reed switch too fast. I have thought about trying a different, perhaps stronger, magnet, but finding one of a suitable size and weight looks like a bit of a lost cause.

I could throw in the towel and buy a new rain gauge, but they all seem to want to come with displays or be wireless or other stuff I just don’t want, with a price tag to match.

I’m about to disable it in the software and bring it inside to see if I can do anything, but at the moment I’m not feeling very hopeful 🙁

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Swimming, 18th November 2021

I didn’t really feel entirely at the top of my game when I went to the pool this afternoon and that showed in my performance. My first four 50m reps were 43s before I got back on track and finished the set all in the 42s, but afterwards my arms and legs were so heavy. In the end I decided to skip the 25m reps. Even quite a few hours later I’m still feeling it in my shoulders and back. I’ve got two days off now though. Perhaps three, given that I’m out for lunch some distance away on Sunday afternoon so may not make it back in time to swim. Hopefully after a rest thing will not be quite so difficult again.

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Swimming, 17th November 2021

Today couldn’t have been more different from the same session last week when there were six swimmers in the fast lane. At times today I had the lane to myself.

I didn’t manage to make all the 50m reps in under 43s though — the first was just over. All the rest were good though, including a few below 42s so I’m happy enough with that for the time being.

The 25m reps were tough afterwards though 🙂

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Esther Dean’s Gardening Book: Growing Without Digging

I mentioned this a couple of days ago. No-one appears to have it for sale, but I managed to find a PDF copy online. I’m now pleased I wasn’t able to buy it. The first couple of chapters are interesting, but I’d suggest the design of her beds isn’t really suitable for the UK because they’d just attract so many pests, particularly slugs and snails, but quite possibly also small rodents.

Chapter 3 is where I lost the plot though. She starts going on about dowsing and, well, no. Just no. You can be scientific or you can believe woo-woo. Dowsing is woo-woo. It has been discredited so many times when properly tested that it’s not even worth further discussion.

Chapter 4 on pest control and companion planting is a bit suspect as well, I’d suggest. I particularly dislike the use of the expression “It is said that A does B”. Lots of things are said. The mere fact that it has been said, even regularly repeated, doesn’t make it true though. The story that French Marigolds kill nematodes is repeated along with the fact that the nematodes can damage your plants. In fact, it’s one particular nematode that’s the problem and it’s most likely to be an issue in monoculture large-scale farming, and not in a temperate climate such as we have in the UK either. It is alleged that garlic “disinfects” the soil. What on earth can that possibly really mean that’s useful? And slugs are apparently attracted to compost. Really? Why are my compost heaps not full of slugs then? Why have my no-dig beds that are covered in tonnes of compost not themselves been covered in uncountable numbers of slugs this year? Sure, I’ve found some, but no more than I’d usually expect and perhaps not even that many.

Chapter 5 is all about comfrey and whilst some of the suggestions seem sensible, others are a little more out there. For what reason, for example, without resorting to further woo-woo, would I want to take a “blood cleanser”? What does that even mean?

The final chapter discusses compost and fertiliser some of which seems eminently sensible. But I quote:

The most important factor in the construction of the compost bin is that the bottom of the bin must be open. There must be earth contact with the compost. I believe that magnetic rays, radiation and other forces come through the bottom of the bin to aid in the rotting process and help produce a really first class result.

You what?! Not that I’d disagree that the bottom of the bin should be open. Absolutely so. But the rest of it…

Apparently air holes are necessary in the sides, too. Probably to allow the gnomes that live in the compost bins to breathe.

In conclusion, if you are curious about the history of “no dig” don’t let me stop you buying the book (if you can find it) or reading the PDF. Just don’t believe every word (perhaps not even half of them) that it contains.

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No dig diary, 15th November 2021

These are my eight leaf radish plants in the polytunnel

Or they would be, if one hadn’t gone missing last night. I found its remains about twelve feet away over the other side of the tunnel with the root mostly missing. I really don’t think it’s slugs. And in fact, given that the plants are about 10″ tall, I suspect it wasn’t a mouse either. I’m thinking that it may well have been a rat. To add to the annoyance, some of the plants that I put in yesterday to replace ones that had already disappeared also went missing overnight 🙁 Measures will have to be taken.

The gardener came back this morning to finish off the work he’s been doing for the in-laws, so I fed another three trailer loads of stuff through the shredder. I’m pretty much on the point of declaring compost bin #1 full once again. We still have apples to press, so I might add the spent pomace from those mixed with some chipped wood and then start on bin #2.

I also managed to fill another two dumpy bags with fallen leaves. Fortunately I discovered another seven empty bags, so I don’t think I’ll be going short for a while.

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Swimming, 15th November 2021

I’d decided that as I had increased my interval time to allow myself to focus on changing my technique, if I can make all my 50m reps faster than 43s then I’ll reduce the interval time by 5s. As yesterday’s were all faster than 43s, today I did just that. And swam every rep below 43s again 🙂 I think knocking off another 5s so quickly might well be a bit of a killer though and perhaps I need to do a few more with the current interval time. Maybe I should say “Knock 5s off the interval time if I do all the reps under 43s, but no more than once a week” (or possibly even once a fortnight) to allow my body time to adjust to the demands of working harder.

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No dig diary, 14th November 2021

This morning I weeded the greenhouse and polytunnel. There weren’t very many in the greenhouse and what there were in the polytunnel were mostly self-inflicted — germinated seeds from the marigolds I had planted between the tomatoes. Something has been nibbling at the salad leaves in the polytunnel to the point where a few have completely disappeared. It doesn’t look like slugs though, as a couple were pulled up completely and there were leaves that had been dragged away from plants. I found a few holes burrowed into the ground around the edges of the tunnel, so I’m wondering if it might be mice. I’ve done my best to break them up and I’ll have another look tomorrow. I also had a bit of a tidy up of the peppers and chiles, collecting fallen leaves and pruning off any bits that were dying.

The unseasonably warm weather (12°C maximum today) continues to confuse the plants it seems. Some trees have lost their leaves already, others are just starting to get their autumn colours now it’s less than seven weeks to the end of the year, and others are still fully green and showing no signs of shedding their foliage. The sycamores in our hedges have dropped most of theirs and as it hasn’t been very windy they have just been sitting on the ground where they fell. I decided to collect them up to stop them smothering the grass over the winter. I can probably use them to mix with grass clippings next year in the compost heaps. So far I’ve filled four “dumpy” bags and there are probably enough to fill another two in the area I’ve been working on with even more elsewhere. I’ll probably run out of dumpy bags before I run out of leaves 🙂

Dinner tonight is lamb with roasted winter vegetables, using swede, carrots, parsnips, leeks and onions all from the veggie plot. I think it’s only celeriac that didn’t. I could even have provided the coriander seed required by the recipe had I known before it got dark.

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No dig diary, 14th November 2021

This morning I weeded the greenhouse and polytunnel. There weren’t very many in the greenhouse and what there were in the polytunnel were mostly self-inflicted — germinated seeds from the marigolds I had planted between the tomatoes. Something has been nibbling at the salad leaves in the polytunnel to the point where a few have completely disappeared. It doesn’t look like slugs though, as a couple were pulled up completely and there were leaves that had been dragged away from plants. I found a few holes burrowed into the ground around the edges of the tunnel, so I’m wondering if it might be mice. I’ve done my best to break them up and I’ll have another look tomorrow.

I checked over the chiles and peppers and found a few bits that were dying back and going mouldy. I’ve pruned those back to green stalks. I’ve really no idea what I’m doing at this point. I know some people prune their over-wintering chiles back quite hard when bringing pots indoors for the winter, but mine will not be moving from the polytunnel so I have no idea if that would be appropriate or not.

The unseasonably warm weather (12°C maximum today) continues to confuse the plants it seems. Some trees have lost their leaves already, others are just starting to get their autumn colours now it’s less than seven weeks to the end of the year, and others are still fully green and showing no signs of shedding their foliage. The sycamores in our hedges have dropped most of theirs and as it hasn’t been very windy they have just been sitting on the ground where they fell. I decided to collect them up to stop them smothering the grass over the winter. I can probably use them to mix with grass clippings next year in the compost heaps. So far I’ve filled four “dumpy” bags and there are probably enough to fill another two in the area I’ve been working on with even more elsewhere. I’ll probably run out of dumpy bags before I run out of leaves 🙂

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