Flyball ETS: Technical overview and shopping list

We’ve arrived back home safely after a smoldering hot EFC 2015 at Emtmannsberg, Germany. My thanks go out to Flyball team Oberfranken who organised a near perfect EFC! Our first team, the Green Angels, became 2nd in division 1, not a bad performance if I do say so myself!

In this article I will give a more technical introduction to the ETS system, I’ll give a high-level overview of the various components which are used and for what.As most components are ordered from China you need to be patient with delivery times, 2-3 weeks on average but some components might take 4+ weeks. The upside is you only spend about 30% of what you would spend when ordering everything inside Europe, and since I’ll need a couple more weeks to publish the rest of the building plans, you have the time to wait for everything to arrive.

Using this link you can find a Google sheet which contains the latest version of the shopping list, below I will go over each part on the shopping list and describe what it’s used for, and if there are possible alternatives you might already have laying around. Check the sheet in the link to see how many pieces you need of each component. Some components have a minimum order quantity (which is written in the MOQ column), to they will be more expensive to order the first time. Keep in mind that the prices in the sheet I linked to are probably not up-to-date as AliExpress prices tend to fluctuate quite a lot. In the spirit of openness and transparency, I would like to clarify that all the links to AliExpress product pages are affiliate links, meaning that if you buy the products by clicking the links I provide, I will get a small percentage of the sale.

Overview

General purpose components

• Prototype PCB: In total we need to build 4 PCB’s, there boards are very nice for this job in my opinion, they have 2 independent traces going over the whole board, which can easily be used for GND and V+ signal. Unwanted traces can be cut using a simple cutter knife. Feel free to omit if you have another type of prototype PCB available, you will need to take care of PCB layout yourself though.
• Nylon Spacers & screws: The PCB’s will be screwed tight to the housing using these nice nylon spacers and screws. Feel free to omit if you have similar iron spacers and matching screws laying around.
• Capacitor & Resistor assortment: You need various of these throughout the project. Feel free to omit if you have the basic resistor and capacitor values laying around.
• XH2.54 connector assortment: All connections will be made using these nice connectors, they ensure a tight fit but easy removability if disassembly is required. Feel free to omit if you have any other type of connector laying around, we need 2-, 3-, 4- and 9-pin connectors. When ordering, eave message to seller when ordering say you want the following sets:
  – 16x 2P
  – 60x 3P
  – 16x 4P
  – 8x 9P
• 2.54 Female pin header (straight): The female pin header is used to build a ‘socket’ on the mainboard PCB into which the arduino pro mini can be plugged.I was not able to find these in lower quantities (you only need about 1 strips, this link buys you 10 strips…)
• 2.54 Female pin header (angled): The angled header is used to solder onto the bluetooth module so it can be easily plugged onto the arduino pro mini’s programming pin headers. I was not able to find these in lower quantities (you only need 5 pins which is small part of 1 strip, this link buys you 10 strips…)

Core components

• Arduino Pro Mini 16Mhz: This is the heart of the system, the arduino pro mini does all the processing of the signals received by the photoelectric sensors and calculates race timings. It also controls the lights and display and takes commands from the remote control receiver. I choose the pro mini because of its small footprint, and the fact it only has pin headers as connections, which makes it simple to create a PCB around it. If you want to buy the pro mini elsewhere, make sure to get a version which has pins A4-A7 available, as this is not common in the pro mini models which are out there, and we really need all the IO pins!
• Photoelectric sensor E3F-R2NK: These are the photoelectric sensors we’ll be using, they are relatively cheap which matters because we need 20 of them! I tried with 10 but that resulted in 15cm vertical gaps between the sensors, which is too much space (a dogs head can fit in between) to get reliable readings.
• 40×4 LCD display with LED backlight: This is the display which is used to show all the timings and status of the system. As mentioned in the beginning of this article this is not the display I used! Since I am not able to find the exact same display anywhere for sale anymore. This display should be compatible but is slightly smaller (19×5.4cm vs 28x8cm of the one I used).
• Bluetooth module: This bluetooth module can be used to program the arduino remotely (I will show how in a later article), it was very handy for me while I was developing the system. Since you might be building to my instructions, and don’t need to develop, you might not need/want this. Keep in mind that I plan/hope to make a smartphone app which will communicate over bluetooth. You can always add it later off course.
• BC557 PNP transistor: The photoelectric sensors we’ll be using work on 12V power, meaning they also emit a 12V signal when their beam is not broken, this is too much voltage for the arduino’s IO pins to handle (5.5V max). Therefor we will use 2 of these transistors to convert the 12V signal to 5V (by adding a voltage divider circuit to it), and also to swap the signal (LOW to HIGH and vice versa).

alignment aids

These components are needed to help you align the active gate side correctly to the passive (reflector) side:

• Laser dot diodes: We need 2 of these to mount in between the sensors, they will throw a red dot on the passive gate side which can be easily aligned with a pre-marked spot to ensure perfect alignment.
• LED 5MM: Actually we just need 2 LEDs, but for the price I decided to order a whole assortment, feel free to omit this if you have suitable LEDs laying around. The LEDs will be mounted below the display to give a visual representation of the sensor columns status. It allows us to easily see if a beam is broken.
• 555 timer: This well known timer IC is used to create a simple 555 monostable circuit which allows us to powered the laser diodes for a given time by the simple push of one button. Since the lasers can blind the dogs I wanted to make this circuit fool-proof (instead of using a simple switch) by preventing someone from forgetting to turn of the lasers.
• 1M trimpotmeter: This trimpot meter is used to control the amount of the time 555 IC provides power to the laser diodes after the button is pushed. Using a 1M potmeter with a 100μF capacitor allows us to adjust the time between 10-110 seconds.
• Waterproof pushbutton: This pushbutton will be used to trigger the 555 IC to power the laser diodes.
• Laser dot diodes: These are the laser diodes which we’ll use. They feature a screw-able head which allows minute focusing of the laser beam.
• Circular bubble spirit level: This is a simple plastic spirit level bubble which will be built into the top part of both gate sides, it will allow us to easily position both sides to be perfectly upright.

Controls & connections

Active gate side view

• Waterproof latching switch with LED: This will be used as the main power switch. It is waterproof and features an LED ring around the button itself to indicate whether the system is powered or not.
• 2NO 2NC waterproof latching switch: This switch is optional, I added it to have the option of swapping around the pins of the 2 photoelectric sensor columns going to the arduino. Since the software expects one pin to be the ‘box-side’ and the other to be the ‘handlers-side’, either you always have to set the active sensor gate on the same side of the lane, or with this switch you can swap the order allowing the active gate to be installed on either side of the lane.
• Waterproof connector: This connector will be used to charge the battery in the system. It features a screw-on cap which seals the connector watertight, allowing it to be out in the rain. One downside about this connector, is that it comes delivered with the innards the wrong way around for our needs. Out of the box the male pins are in the connector on the cable side, meaning that they are exposed to be touched when the cable is plugged into mains power! Therefor we need to disassemble the connector so that the more protected female pins are in the cable side connector. The cable side of the connector can be screwed onto the panel side of the connector as well, allowing a watertight seal with the cable connected. So if you have a flat battery and it’s raining during practice, no worries, just plug it in.

Power

Power distribution PCB

Battery

• DC Switching regulator: This system requires both a 12V and 5V power circuit, therefor we will use a 12V battery and use this small, cheap and efficient switching regulator to step down the 12V to 5V voltage.
• 12V 6800mAh battery (link old battery): A small, relatively cheap 12V battery with enough juice to last about 5-6 hours, which should be enough for any practice session. Small downside: It comes with a small LED inside to show whether the battery is outputting power or not, it also has a switch to switch the 12V output on and off. Since the battery will be inaccessible when the system is assembled, we don’t need either of these. The switch can be left in place, but since we will keep the battery turned on, we can’t have the LED drawing power all the time, so the LED has to be taken out, which is quite easy. (update 08/02/2016) The striked-out text was a problem with the previous battery I suggested (see ‘link old battery’), the current link will get you a battery without LED or switch which is exactly what we need.
• Power supply AC to 18V DC: (update 08/02/2016) In my original article I used the AC to DC charger that came with the battery, but it crapped out on my after 6 months of use. Looking at the components the charger was not very good quality, so now I suggest to order a seperate power supply and battery charger. Since our battery needs to be charged to 12.8V to be full, a 12V power supply won’t cut it. You need an 18V power supply and the charger circuit below will make sure to provide 12.8V to the batttery
• 12V Battery charger circuit: (update 08/02/2016) This little PCB will take the 18V from our power supply and regulate it to the 12.8V our battery needs. It has potentiometers which allow us to regulate the voltage, charging current and ‘battery full’ threshold at which the LED will turn green to indicate full charge.

Remote

• Remote + receiver: This is the cheapest 6 channel remote/receiver I was able to find, while the article claims 1000m range, I have not been able to get more than 4-5m out of it. However I suspect this is at least in part related to the fact that the old LCD display I’m using requires a high voltage converter for the backlight, I suspect the high voltage is causing a lot of interference.
• 23A Battery (12V) for remote: These do NOT come with the above remote + receiver combo, therefore we need to order these as well.

Lights

Light control board

One finished light

• LED RGB 5050 strip per 5cm (non-waterproof!): The lights as I’ve built them are made up out of RGB LED strip pieces, they are 5050 SMD LEDs with 60 LEDs per meter. Each light conists of 4x5cm strips meaning 12 LEDs per light. Using RGB LED strips is certainly not required, in fact only 2 of the 12 lights need to output 2 different colors, for which RGB is required, but given the low price of these RGB strips I couldn’t be bothered ordering 4 different LED strip colors. These LEDs consume 0.24W MAX (max=each color turned ON) each, which translates to 0.02A at 12V. Since we have 12 LEDs per light, this means we have to take into account each light can pull up to 2.88W or 0.24A each.
• 74HC595 Shift register: To simplify cabling and save outputs on the Arduino, I used a 74HC595 shift register to control all lights. It allows us to use only 3 pins on the arduino and get 8 available outputs in return.
• ULN2003: Our RGB LED lights can pull a maximum of 0.24A each, and we have two lights linked together each time (for both sides of the gate), so for each 2-sided light, we need 0.48A, this is too much for the 74HC595 to control directly (check its datasheet, it says max 0.035A per output). Therefor we use this ULN2003 which is simple transistor array consisting of 7 transistors capable of providing 0.5A each, just enough with some headroom for our LED lights.
• Prototype PCB simple (no tracks): These PCB’s will be used to stick the LED strips onto, we will then use the back to solder wires in place which connect the LED strip pieces end-to-end.

Housing components

The main body of the 2 gate sides is made up out of ‘PVC Foam’ plate, it is a material which has a thin layer of solid PVC on either side, but in the middle it consists out of PVC foam, which is quite flexible and makes it light. Since it is 100% synthetic, it is really well suited to handle the elements. Also the 10mm thick version of this allows nice big 4×30 stainless screws to be used without pre-drilling holes!

The cost of these PVC foam plates, is a considerable chunk (+20%) of the total price, so here’s a small tip: These PVC foam boards are used a lot in advertising, so if you don’t mind using a board which isn’t perfectly clean, look around at places which might have old advertising boards they’re willing to part with. Local sports clubs are a good place to search.

Note that the links I provide for these materials are local to me, depending on where you are they might not ship to you, or ask a high shipping fee. But since these are fairly common materials, you should be able to find them locally. In fact I bought my acrylic glass plates in a local DIY shop.

• PVC Foam Plate 131x79cm 10mm thick (optimal cut layout with 1mm saw kerf): Important: These are the measurements you need if you have a saw with a 1mm thick saw blade (1mm kerf), if you will use a saw which has a thicker blade, you will need to order more material. In fact I would always advise to order more material in case you mess up a cut and have to do a piece over.
• Acrylic glass plate 5mm 67x30cm: The 5mm glass plate will be used on the front of the active gate side, since it has to allow the beam of the sensors to go through. I can confirm the sensors I’ve listed work through acrylic glass of 5mm thick. If you choose other or thicker glass there’s a chance the sensors won’t work!
• Acrylic glass plate 3mm 5x81cm: The 3mm thick glass will be used to cover the LCD display and the lights. By using some transparent silicone we can make a nice seemless and waterproof sealing.

Feet

The feet are another delicate story, I actually spend a lot of time before I had figured something out that would work the way I wanted, in the end I think I might have overdone it a bit. Yes the feet are sturdy and allow for minute adjustments, but the materials to build them cost a whopping 109Euro! That is almost 26% of the price of the entire build! So I leave it up to you if you want to replicate my build, or try something different. One of the ideas I’ve heard, is to use a fixed flat foot, and use window packers to put underneath at various places until the gates are upright. Not as nice as what I made, but certainly a lot cheaper. Keep in mind that it’s good to be able to separate the feet from the gates, it makes storage and transportation a bit easier.

One foot unpainted

Partly finished gate side on foot

Also note that I bought these parts in local shops, ordering heavy metal parts from China isn’t cheaper than buying locally it seems :). I have only listed a website for the IPE beam and the iron tube I used, so you get a clear description of what you need.

• 30cm IPE Construction beam 160x80mm: These will be the main parts for the feet, they are relatively small but heavy, ensuring the sensors won’t topple over when a heavy gust of wind hits them. I recommend ordering 2 pieces of 30cm, opposed to ordering a big piece and cutting it yourself, as these beams are about 7mm thick steel, and thicker in some places, you will need some serious machinery to cut them to size.
• 5cm 60.3mm steel tube 3mm thickness: You need 2 pieces of 5cm of this steel tube, I ended up ordering 50cm and cutting them myself, which is fairly simple since it’s only 3mm thick. These 2  pieces will be used to cover the trailer hitch ball and accomodate the screws to lock onto the ball.
• Trailer hitch ball 50mm: You need 2 of these which will be mounted onto the IPE beam pieces, using a ball allows for 360 degree adjustments of the gate to position them upright.
• Steel mounting plate 24x8cm: You need 2 of these plates which will serve as a baseplate for the gate sides to be mounted on top of. They will need the steel tube pieces welded to them.
• Hand/star screw M8: Feel free to omit these for simple hex M8 screws if you want, but these have the advantage that they can be screwed by hand, ensuring you won’t need any tools/wrenches while setting up the gates on the field. The link I provided for these is actually from a German Amazon seller who does not ship outside Germany, it’s mainly for illustration purposes. If you’re in Belgium, check out Fabory, they have several shops throughout the country, and they specialize in ‘screws’, you can go in there and ask them for any type of screw, and they’ll have it!
• M6 stainless screw: These screws (12 in total) will be used to mount the gate sides onto the steel baseplates. Make sure to use stainless to prevent them from rusting.
• M6 stainless head nut: Also 12 of these are needed, you could save a few cents by using regular nuts, but I like the finished look on the head nuts.
• Dupli-color rust stop 4-in-1 white spray paint: As most part of the feet are not stainless steel, we should give them a paintjob to prevent rust from eating them up. Feel free to omit if you don’t a nice white look and are prepared to wipe off the sensors after a rainy practice to prevent rust from setting in. I had to use about 25% of a 2nd bottle to paint my 2 feet, so you have to buy 2  bottles.

Right tools for the job

In this section I will describe some of the tools I used which might not be very obvious. I will not describe ALL the tools I used as first of all I don’t remember 🙂 and second there are more than one ways of doing most of the build, so just use whatever tools and methods you comfortable with.

• Makita HS300D cordless circular saw: I used this saw for cutting both the PVC foam plates and acrylic glass. It cuts through both materials relatively easy and has the advantage of having a saw blade which is just 1mm thick.
• Makita DF330D cordless drill driver: This nice and lightweight drill driver is just what you need for this build. I have another heavy 18V makita drill driver, but in case of this build you don’t need that kind of power, and then it’s just nice using a lightweight tool which is easier to handle.
• Proxxon IBS/E rotary tool: I used this in combination with the proxxon accesory router base to route cutouts for the lights and glass plates. It has the advantage that’s lighter and smaller than a regular router which might not be able to route as accurately as this one.

Conclusion

So there you have it, all the parts and components needed to create the Flyball ETS system! Price wise we’re just above 406 Euro, if you order everything new, but as I’ve pointed out in this article, it’s possible to save at least 100 Euro by tracking down used PVC foam plates, and perhaps making the feet a little simpler. If anyone has suggestions on cheaper replacement parts, let me know and I’ll check it out. When I’ve completed all my articles on how to build this system, I’m already planning to start building a second system for our club, with some improvements which should make it easier to build, and preferably cheaper as well.

I will now start working on the build plans for the housing of the gates, which will be described in my next article, so keep your eyes peeled!

Update 1 (30/08/2015):

I realized while making the electronic schematics that the BC547 resistor on this shopping list was wrong, it should have been a BC557 transistor. Link to buy was also updated. Sorry for the invonvenience if you ordered the BC547 already.

Update 2 (03/09/2015):

My list wronly said ‘BC557 NPN transistor’ , it should have been ‘BC557 PNP transistor’. This has been corrected

Update 3 (08/02/2016):

After 6 months of use the battery charger of my first ETS gave in. This was more or less to be expected as the charger came for free with the battery (which was already dirt cheap). I placed a seperate AC to 18V DC power supply and battery charger circuit on the shopping list, this is what I’ve also installed into my ETS build and which I presume/hope will last a lot longer. It makes the total build more expensive by about 15 Euro but it saves you having to re-open the box after 6 months :).

I also replaced the battery by a model which does not have a build in power switch and LED. We didn’t need either of these and the original battery I suggested required you to remove the LED to prevent it from draining the power overnight.