Double bucket

 

Couple of years ago me and Jakke where conducting some lightning measurements. We were in a hurry and on a budget. Well, perhaps not so much on a budget as I was (and am) fond of cheap solutions. What we came up with, was a way of using some 50 mm by 50 mm sawn softwood (likely spruce or pine), some plywood and a couple of polypropylene buckets to make a fairly durable weather cover. These could be used for example as part of an open monitoring project.

Since I’m lazy, I didn’t bother to dismantle them after the measurements ended and a couple of these have been out in the weather (Southern Finland)  for about four years. Today I finally decided to take them a part. I found out that they have been holding up pretty well and would likely have been up to their task for at least a few more years. So if you are looking for a way of making a similar system, below I explain how to make them. At the end are a couple of pics and comments on the dismantled set.

White buckets were used in an attempt to keep the electronics cool. Other colors may be used depending on location to make it less visible.

Figure 1 shows a rendering of the two ways we used to setup the systems. In the left the stud is driven to the ground. I used an iron bar to first make pilot hole and then carefully using a small piece of plywood as protection (between the sledge hammer and the pillar) hammered the stud to the ground.

In the right is the system we used on a (Melbourne) Florida roof top for a couple of months to create a more temporary measurement setup. We used some concrete blocks as additional weight just in case. If you are considering a more permanent system consider adding some steel wire to attach the system to something really heavy. You don’t want it hitting someone when it is picked up by hurricane winds or a tornado.

Cheap weather cover for measurement devices
Figure 1. Cheap weather cover for measurement devices

Figure 2 shows what you need. All sizes are approximately those we used, select your bucket size to match the size of your device and scale everything else accordingly.

  1. Two short pieces of wood. One should be short enough to fit side ways in to the bucket and one should be about 5 cm shorter than the bucket is high. One long piece of wood, it will determine how high the rest of the system sits.
  2. A piece of plywood, cut a circle that fits in to the bucket to a depth of about 5 cm
  3. Two buckets
  4. Some screws and hot glue
  5. a saw, (sledge)hammer, screwdriver, eye protection etc.
Figure 2. Things you need
Figure 2. Things you need

As shown in Figure 3 set the longer of the two short pieces of wood on top of the plywood. Use hot glue or two screws or both to attach it in a manner that it can’t rotate around the vertical axis. Before this, make any openings you need for electrical wiring and such.

Figure 3. Set one of the short pieces on top of the plywood.
Figure 3. Set one of the short pieces on top of the plywood.

The shorter piece of wood is then attached on the other side of the plywood. Select the correct length for the support pillar and after driving it to the ground attach the plywood to it. If any of the wood surfaces is curved using copious amounts of hot glue between surfaces before inserting the screws will make the system more solid. The inner bucket is attached with one screw, which is driven through the bucket bottom to the piece of wood shown in Figure 3. Note that you will be driving the screw in the direction of the grain, do it carefully or the strength of the attachment will be reduced.

Figure 4. Attach the shorter piece of wood as shown and put the bucket on top of the assembly
Figure 4. Attach the shorter piece of wood as shown and put the bucket on top of the assembly.

Add the other bucket, this one stays in place by gravity and friction. If you use a screw, rain will seep in.

Figure 5. Add the other bucket.
Figure 5. Add the other bucket.
Image 1. Two systems, the outer bucket has been removed from the one on the left.
Image 1. Two systems, the outer bucket has been removed from the one on the left.
Image 2. View from below.
Image 2. View from below. Looking good, all the wood is still healthy.

 

Image 3. View inside the protected area. Apart from some spider web its like new.
Image 3. View inside the protected area. Apart from some spider web its like new.

 

Image 4. The support structure. The limiting factor for the operating life of this setup is likely rotting at the air ground interface. I was able to snap the wood by tapping the sharp end to the ground
Image 4. The support structure. Limiting factor for the operating life of this setup is likely rotting at the air ground interface. I was able to snap the wood by tapping the sharp end to the ground.

Figure 4 shows the support structure and the weak point at the air-ground interface. Rotting has reduced the strength of the wood. If the place where measurement are taken is not very sensitive, consider using wood that has been treated to protect against rot. Using a larger size like 75×75 or even 100×100 mm2 will likely also give you a couple more years of service life.

Image 6.
Image 5. Ultra violet radiation has made the plastic brittle. Some erosion was also visible on the surface. Note the white stuff at the end of the screw. This screw was used to hold the inner bucket in place and the Zinc protection was showing signs of wearing out.
Image 6. Markings at the bottom of the bucket.
Image 6. Markings at the bottom of the bucket.

 

Feedbacks and bonuses

 

When I try to think through some phenomenon or a policy proposal I like to look for feedback loops. Perhaps this is a result of my background, while I’m not an engineer I have been exposed to so much electronics that I sometimes slip into thinking that the world is like an electronic circuit. This is not as bad as it seems, one just needs to remember that a lot of work has been done to make electronic components behave like their theoretical counterparts. Human behavior is usually quite complex and careful consideration is needed when decisions are made based on a simplified model.

A definition for feedback can be found from wikipedia. As an example: picture a large dam made of sand. As long as the water level stays low enough the water stays in the reservoir, but if even  a small trickle starts, it takes some of the sand with it and makes a better channel for the water. This in turn makes the trickle larger, which takes more sand with it. Pretty soon there is a ravine and the water is rushing out. This is positive feedback, the flow is amplified by the feedback (i.e. erosion of the channel). Reaction of the system to a change is to change the system more to the direction of the change. In negative feedback the feedback signal has an opposite polarity compared to the change. This can result in a system that stays close to a value as it tends to return to it after a disturbance.

Money can act as a feedback mechanism. You get paid, you show up at work and usually do what you are told to do. You are promised a bonus and you work hard to earn it. Sounds fairly simple and foolproof. But is it?

I have been lucky enough to work in organizations filled with experts and as is sometimes the case in such organizations, my boss has usually known much less about what I have been doing than I do. In this situation I find it difficult to put much emphasis on verbal praise, after all my boss didn’t really know how hard it was to achieve my targets. So the one feedback mechanism available has been money. Targets are set, I exceed them and I get a fat bonus. Everybody is happy.

But after a few years I realised that I seldom thought about the extra reward when I was working. When extra money was the sole motivator the value of my contributions were “perhaps” smaller compared to situations where I was internally motivated. The feedback loop didn’t close and in practice the money was wasted. This excellent story and this fine clip seem to explain why. According to the video if a task is difficult money is a bad motivator. Apparently this has been proven by many experiments. I blame someone for not telling me.

“Creativity”: catapult camera

 

Catapult camera

The “catapult camera” is an example of a project that produced no useful outcome whatsoever. It is included here as an example of a solution that did not find a problem.

The idea was inspired by mast (telescope) camera systems that can be used to map and monitor for example disaster zones. Typical weights for such systems appear to be a few tens of kg, and are capable of supporting camera weights of 4 kg or more. Typical costs for commercial systems appear to be some thousands of EUR. Typical heights that can be reached 10 meters. There is a technology which is capable of reaching altitudes well above 10 meters: small remote- controlled aircraft (helicopters or gliders). These are however not cheap technologies, and are not necessarily very robust in extreme circumstances.

We proposed building a catapult which is capable of launching a camera up to about 40 meters altitude, taking images while it is in the air, and stitching a panorama image of the pictures.

Full report: Download: CatapultCamera-Final.pdf

Outcome: The solution has far to many issues to be useful in real life. Projectiles are likely to get lost or broken; the image quality is far too poor to be useful. Most problematically, the cost of radio-controlled drones is plummeting, and these will be more competitive in every imaginable way. The problem is valid and important, the solution is not.

Team: Jakke Mäkelä, Niko Porjo, Kalle Pietilä.

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