Mexico
In autumn of 2018 my company declared a limit to the amount of holidays I could transfer to the next year so I had to squeeze in a short holiday. After checking flights to wherever, I noticed there were direct flights to Cancun, Mexico or the island of curacao. I decided to book a 1 week trip to Mexico due to the possibility of a mixture between diving and seeing some mayan cultural heritage sites. The amazing Mezcal hostel turned out to be the perfect spot to stay in Cancun and meet people to spend the evenings with.
Despite the short time, I managed to see the heritage sites of Chichén Itzá and Tulum as well as dining on the beach in Playa del Carmen, see some baby turtles on Isla Mujeres, swim in the pristine waters of the cenotes in the middle of the jungle and party in Cancun’s famous Hotel/nightlife area. Of course, I also went diving in the ocean and a cenote to witness the halocline (border between sweet and saltwater) that give you the impression of fish and divers flying in the sky while raising your head out of a lake. Unfortunately, diving is relatively expensive in Mexico and they try to make money by selling pictures (80$ for ~5 pics the professional took of me and none showing the incredible ) so I couldn’t take any pictures in the cenote Chac Mool. If I were to fly to Mexico again, I’d definently make it a multi-stop trip and slowly travel down towards Belize and the other neighbouring countries.
Bergen – Norway
On a perfect weekend trip to norway, we made a roadtrip to stavanger to hike preikestolen – The weather wasn’t perfect but the scenery definetly is!
Mini-Load – a resistive load for testing and prototyping
When developing electronics, it can be useful to have a way to draw or measure a specific current. While professional digital loads are quite expensive, a high-wattage resistor is sufficient in many cases. To have a small ( 16,5 x 10 cm), universally usable resistive load, I ordered a selection of resistors that allow me to draw commonly used currents like e.g. 50mA, 100mA, 200mA, 0.5A, 1A… for the common voltages of 3.3V, 5V or 12V. Additionally I included 0,1 Ohm resistors as shunts for measuring the current. To facilitate the combination of the used resistors to the desired total resistance, I placed the terminals at 19mm to use existing lab-socket jumpers and decided to connect the left & right resitor permanently. While this has the drawback of not allowing concurrent use for 2 outputs at the same time, it reduces the amount of required cables as well as plug/socket and cable resistances and inductances.
Costs ~ 55 €
Time ~ 3 h (excl. planning 😉 )
Materials used:
– 2x resistors WD25 (25W) 0,1 Ohm [5 €]
– 2x resistors WD25 (25W) 1 Ohm [4 €]
– 2x resistors WD25 (25W) 3,3 Ohm [4 €]
– 4x resistors WD25 (25W) 10 Ohm [7 €]
– 4x resistors WD25 (25W) 100 Ohm [7 €]
– 1x aluminium heatspreader 160 x 100 x 40 mm [ 15 € ]
– 2x aluminium stripe (320 x 10 x 2mm, bent with 90° angles as 10-70-160-70-10 ) [1,5 €]
– 1x aluminium stripe (250 x 10 x 2mm, bent with 90° angles as 45-160-45 ) [0,5 €]
– shrinking tube for isolation of the ‘feet’ [0.5 €]
– 40x short self-cutting screws (e.g. 9,5 x 3 mm) [2 €]
– 21x colored 4 mm lab-plug terminals [4€]
– solder-wire & desolder-wire (or some fine copper-mesh / wire)
– thermally conductive adhesive tape (double sided) [4 €]
Tools:
– drilling machine (preferably with a stand for 90° angles)
– soldering iron
– scalpel / cutter / scissors for the tape
– Isopropanol as drilling lubricant
– 2.5 / 8 mm drills (preferably sharply cut, cobalt coated drills)
Malta
I’ve been wanting to dive in Malta for a few years now but everytime I tried to organize a trip with a few friends oder a long weekend, flights were really expensive. This spring I finally managed to spend a 4-day weekend on this mediterranean island and dive some of it’s wrecks.
The ‘Schollenspiel’ – more LEDs than you can count
tldr; In 2015, the student representatives for electrical engineering at RWTH Aachen university rebuilt an awesome childhood game.
 While I was studying at RWTH Aachen University, I was part of the student representatives for electrical engineering (FSET) for a few semesters. We were elected each semester and besides representing the students in different bodies within the university, we were in charge of welcoming the new students. Luckily, a fund from the university allowed us to spend money specifically for the new arriving students each year for things like building games, renting an inflatable human-soccer-field or having a BBQ. One time in march 2015 I received a message from a friend while I was on holiday: “Martin! do you know the ‘Arktos Superspiel *(1)’? From Tabaluga TV? Do you think we can build this for the first semester student welcome?” I remembered an ‘ice-field’ represented by hexagonal, lit up plates where the children on the TV show were shown a ‘safe path’ step by step. Then, the markings disappeared and they had to walk across the field by remembering the path. Awesome idea, I thought and replied “Well, it’s gonna take a lot of hard work and probably ~3000€ for the materials but yeah, sure we can!”.After being back from my south-america-trip , we started brainstorming and prototyping. Thanks to many helping hands, we recreated this childhood-memory as a game with 60 fields for the first semester students and even won a price at the university. The game is built as a set of 20 modules with 3 ‘ice-fields’ and an RF-module each; supplied by 10 computer-power-supply-modules. 2 transport-wagons were allowed us to store and transport the game and a software with a GUI allowed an easy, setup and automatic generation of the ‘path’ as well as measuring the missteps. |
- 14.940 LEDs (=249m of LED Strip with 60 RGB LEDs/m cut in pieces)
- about 10.000 solder-points on 20 PCBs with 1484 holes drilled manually
- more than 250m of wire in 4.560 individual pieces
- many square meters of 18-24mm thick, robust wood (60 hexagons, 360 frame-pieces with ~720 holes drilled
- 20*2,4GHz Clients, 1 Masterbased on nrf24 and arduino nano like PCBs
- roughly 4.000 (unpaid) man-hours invested by different students (thanks to an incredible amount of coffee)
=> about 4.000 watt power-consumption and lots of fun!
It’s important to note that all of us worked without pay and spent many hours of our free time (even during the exam phase) to create an awesome experience for the first semester students. Thanks again to everyone who helped to realize this idea!
Some of the main issues we encountered:
- LEDs emitt light at an angle of up to 130° but if the glass is palced too close to the LEDs, individual LEDs are visible. We tried different acrylic-glasses up to 8mm but girl’s heels or small stones in the profile of a shoe could still have broken the acrylic glass with 50-100kg being concentrated on 1 spot. For a homogenous light-effect, we would have needed at least 3cm between the LEDs and the ‘glass’-surface while being able to withstand high pressure. The only solution that might have offered these properties would have been translucent resin or at least 12mm acrylic glass mounted around the edge. Both are options that were out of our budget so we settled for thin, 3mm acrylic glass with ice-optics being placed on the silicone-film of the water-resistant LED-strips.
- Pressure sensing was another task we had to solve. We tried load-cells, capacitive or optical measurement with spring-loaded inner-hexagon-plates, pushbuttons and piezo-electric force-sensors. In the end, the simpelest solution was the best: ESD-foam! The black foam used for packing electronics has a high electrical resistance (but is conductive). When the foam is compressed, many ‘bubbles’ form a short circuit and the resistance decreases by a huge factor ( 10kΩ to 5.5kΩ ) so we didn’t even need operational amplifiers . The foam also expands itself afterwards. For this, we placed a copper-strip on the bottom of the hexagon-frame and on the bottom of the LED-plate with a piece of 4mm thick foam inbetween.
Ps: To avoid any risk for the students / children that might play the game, we kept all self-built parts at the 12V-level and used standard PC-power-supplies to power the game.
(*1) The name ‘Arktos superspiel’ is most likely trademarked by Tabaluga TV but not know outside of the german speaking community. If you want to know more about the game, feel free to google the name and rewatch some old episodes on their channels/websites
Building a micro Quadcopter (130mm)
180mm was still quite big and the frame wasn’t really built for folding so I went down to 130mm. Here you can see a few pictures of my first built which I have since crashed and disassembled a few times :D. New parts are on their way so you can expect some new builds around the 130-180mm size in the next months.
Travel gadgets #1 – chargers and adapters
tldr; get a 4x USB travel adapter with folding US-plug and adapters for UK and europe-plugs. If you bring cameras with more than 1 battery, get a usb-charging-bay. If you bring a laptop, get an SKROSS universal adapter (for world trips) or buy an individual UK/US/EU-adapter if you only travel in 1 area.
When travelling, some gadgets might come in extremely handy.
Luckily we live in a world where most devices charge via USB and most cameras can be made to charge via USB with adapters. So here’s a short overview / suggestion, what to bring on your holiday.
Travel Adapters
Unfortunately, there is not 1 standard power-socket but ~4 sockets with different implementations, mostly used around the world. Some countries (especially in southeast-asian hostels) opt for power outlets that are already compatible with multiple plugs but being a european, the plugs with a safety-ground-connection (3 Pins / “Schuko”) might be a problem, although their number is decreasing in laptop chargers and mainly hairdryers and irons are the last remaining portable electronics requiring these huge plugs.
Warning: Using a 2 to 3 pin adapter could be extremely dangerous and (at least in germany), those are prohibited from being sold. Please refrain from using any cable-powered device without connecting the protection pin and use a proper adapter for these purposes!.
When buying one of these, make sure they have a replaceable fuse and bring a spare (the fuses will most likely blow if you use a hairdryer or an iron – trust me, this happened 😀 !). As you can see, they are quite bulky so if you’re only in 1 country or area, getting a simple adapter for this country might be cheaper and easier.
Devices in need of power
| Smartphone & Tablet | USB (micro / C / lightning) | |
| Laptop | power-socket or USB-C PD (if new) | socket adapter needed! |
| Actioncamera | USB (micro / C ) | optional multi battery-charger |
| Old camera | battery charger | USB-battery charger! |
| New camera (e.g. Sony Alpha 6000) | USB (micro / C ) | optional multi-battery USB-charger |
| Noise cancelling or bluetooth headphones | USB (micro) | |
| Flashlight | single-use batteries / lithium battery | USB Adapter usually included |
So most newer devices can already be charged via USB and for most cameras, there are small USB-battery-charging bays availible as shown below. To account for the unexpected awesome adventures, I’d always prioritise a charger over a 3rd or 4th battery for my camera.
Besides the charger that came with your phone, there are also many capable multi-USB-chargers with different features – here’s what you should look for:
- 2.1A or more per port; total power should be “number of ports you need*2.1A” – on remote islands, there might only be power for ~2 hours per day and you want to refill your powerbank, camera and phone fast!
- if your phone has QuickCharge (2,3) from Qualcomm, check for QC2 or 3 qualified chargers
- if your phone/GoPro has USB-C (usually paired with quickcharge) get a charger with USB-C according to your phones’ quick charge capability:
- QC2 / 3 Phones –> Qualcomm Quick charge capability
- Huawei (e.g. P10 / Mate 10) –> check the comments and questions on amazon to see if Huawei quick charge is implemented. Some USB-PD certified chargers might work
- OnePlus – sorry, I don’t think there are multi-usb-chargers with this capability
- USB-PD (also for some macbooks) get a powerful (18W or more) USB-PD charger
- small size and low weight with enough power
- rounded edges, preferably plastic case
- preferably a folding US-plug with clip-on adapters for other countries
- check user recommendations for ‘whining’ or ‘beeping’ or ‘humming’ or ‘noise’ in general. some chargers create an annoying noise, especially when plugged in without charging or when batteries are full.
- user recommendations with 1 star on amazon are always worth a read and might warn you of bad quality 😉
Here’s what I’m currently bringing on most trips:
Travel gadgets #2 – powerbanks
tldr; get a light 10.000mAh powerbank with 2A charging capability, included micro USB cable and an additional USB output.
When travelling, you need to bring a powerbank. You’ll probably use it before you even arrive since constantly being on your phone while waiting in an airport drains the battery really fast.
There are thousands of power banks out there ranging from 1 to ~8 charges for your phone with different features like fast charging (output and/or input), an LED-light or solar-cells – and a thousand tests that mostly ignore some of the following points. Here’s my suggestion on what to get for travelling:
- ignore the solar cells. They charge extremely slow and when you’re more than 3 nights away from any charging port, you should be enjoying nature instead of netflix anyway.
- capacity: 8.000-12.000 mAh. Smaller ones are only good for 1 charge; bigger ones get bulky and you’ll almost never need them
- included native cable for your phone (micro USB / USB C / lightning) – saves space and is really convenient; though it won’t last forever.
- at least 1 additional USB port (for a 2nd device or when your included cable’s plug gets worn after a few years)
- >2A output (if you have a USB-PD or quickcharge phone, get one with the same capability)
- >2A charging of the powerbank itself (if you have a USB-PD or Quickcharge charger, get a powerbank that supports this as well, e.g. with USB-C. Lighting inputs aren’t useful since you could still use your apple charger with a micro usb or usb-c cable)
- plastic case, preferably with a soft-pouch/bag to avoid scratches on other devices and safe weight
- make sure to read the 1 star recommendations to look for manufacturing problems or possibly burned(dangerous) powerbanks
Remeber that if your phone has a 3000mAh Battery, a 10.000mAh charger is most likely only able to recharge it ~2.5 times. That’s not because anyone is bad at math but because the energy gets converted from 3.7 to 5V and back – and you’ll probably keep your phone turned on while charging so it’ll burn through some battery already. Depending on how good your powerbank is, 0,85*0,85 up to 0,95*0,95 (72-90%) of your powerbanks capacity will end up in your phone.
In terms of technologies for the batteries, there are basically 2: round cells and puch-cells. Round-cells are used in e.g. many anker powerbanks and industry wide in a format called 18650 (18mm diameter, 65mm length). There are some manufacturers who use premium cells which are really sturdy and safe. The downside is the weight and wasted space between the round cells, as well as the thickness of at least 20mm (18+cover). Pouch-cells are flat (like the one inside your phone), lighter and more compact but you should make sure not to bend or try to break your powerbank.
For a powerbank that is ready for your next phone, I’d suggest USB-C input and output with USB-PD for charging the powerbank and the acessories you plug in