At Tog Hackerspace, we love helping artists bring their visions to life by combining technology with creativity. One recent project, led by me, Jeffrey Roe, involved modernizing an older artwork that originally used a film camera, and upgrading it to use a digital projector and new sensors. The high-level concept was simple but striking: if a person was detected in front of the screen, the video should stop, and the screen should go black.
This collaboration took place over several months, working around the artist’s availability and my own time outside my day job. We began by choosing a Raspberry Pi as the brains of the project. Initially, I used an ultrasonic distance sensor to detect when a person was present. I wrote the control software in Python, using VLC Player to handle video playback. The script managed VLC through subprocess calls, ensuring that the video would start and stop as needed. To make the setup more seamless, the Raspberry Pi was configured as a server to auto-start, log in the user automatically, and hide the mouse cursor from the screen.
From almost the very beginnings of TOG, our monthly Saturday evening Open Social has been a constant fixture in our calendar. At our Open Social in January 2015, a quick hack over the previous few weeks at making a brick pizza oven from a stack of red bricks and some bits of angle iron turned out to be an unexpected instant hit. Our Open Social was changed forever, and has become as much of an outdoor event as an indoor one, irrespective of the season.
We were blessed in TOG 2.0 (Chancery Lane) to have our own private yard where we could leave the oven permanently. Fast forward to TOG 3.0 (Blackpitts) where there was a large outdoor car park, but we couldn’t leave stuff out there permanently. The solution was to create a mobile pizza oven that we could wheel in and out as required. Using a gym ball as a mould, we made our current mobile pizza oven.
After 7 years of hard use, it was time for a bit of well deserved maintenance. The top was removed and the base refilled and leveled with fresh perlite. New dedicated fire bricks instead of red bricks were laid out for the base. Unlike the previous red bricks, these fire bricks are all identical in dimensions and have now made a super flat cooking surface. The inside of the dome got some re-pointing with new red pottery clay.
At our combined Open Social and 16th birthday party last week, the newly refurbished oven was put to the test. The pizzas were fabulous. Thanks to Conor for making the dough! Being a maker space, you get to prepare and cook your own pizza. We even have peels that we made ourselves. We are a maker space after all! To see the oven in action and to have a go yourself, drop into any of our Open Socials.
A call went out this festive period on the Irish Makers Unite discord server, looking for interest in participating in a Secret Santa project. Our own Jeffrey Roe decided to take part and this is blog post about his build.
The rules of the project were simple: the gift had to be made by the maker. I received a small blurb about the maker I was creating for. They asked for a desk toy. Due to other commitments, I left myself with only two days for the build, so all the parts would need to be from what I have at home or in the hackerspace.
I have a love of making interactive games for science and maker events, but in the past, they tended to be big things that would no way fit on a desk. I decided to build a memory game using a keypad that has been in my parts bin for over five years —an old matrix keypad that I got free at some long-forgotten event.
Each year the Dublin Maker festival comes around and our members Jeffrey Roe and Christian Kortenhorst want to take part. They have been to many maker festivals and collaborated over the years.
Christian likes to make big things with tools and Jeffrey likes to make things with technology and electronics. They tend to come together on their love of interactive games. While wandering around EMF camp last year they came across the work of We Throw Switches and their flux game
The goals of the project:
Two-person interactive game
Fit on a table
Be portable
Simple game with no need for instructions
Be ready in three weeks
Eary on, it came clear we would be using arcade style buttons, and addressable LEDs to meet the project deadline of only a few weeks.
Christian got started working on the box. He create an LED display that was 4 by 6 “pixels”. Each pixel would be made up of 4 addressable LEDs. Two stripes of 50 LEDs would be used and due to the wiring layout, some would be hiddle and just covered in tape.
Doubts started to come to the project team. Would these LEDs work in direct sunlight? Remember the goal is to use the game in an outdoor daytime festival. Christian came up with the idea to paint everything white and Jeffrey said let’s bump up the current to make the LEDs brighter.
Now for the brain of the game. Jeffrey started out with the idea of using the USB controller that comes with buttons. How hard could it be to use a Raspberry Pi Pico and a USB host library?
It turns out that with Jeffrey on the team running Dublin Maker there is not enough time to learn new things for projects. We quickly switched back to using the reliable and known Arduino. In order to make the game responsive all eight buttons would be required to have their own hardware interrupt.
He started to use an GPIO expainder over I2C. This device allows for lots of interrupts. We started to build out a little board that would take the connector from the buttons and power the LEDs strips. The video below shows testing an interrupt to turn on the LED in the button when the button is pressed.
The code started to come together with a few late-night sessions but the interrupts didn’t seem to work as expected. Due to the way, the buttons are wired, the LED and the button share a pin and it’s only controlled by three pins. This causes the interrupts not to trigger when the LED is turned on.
Unfortunately, we did not meet the deadline of the event and never fixed the problem before the Dublin Maker event. We coded up a bit of a demo on the LED display but was not interactive.
The project did not end there. Another big public event was only a few weeks with Dublin Comic Con Summer edition. During a few late-night coding sessions, Jeffrey came up with a new way to check the inputs of the buttons without using hardware interrupts but still be reactive. The code just checks the status of the expected two buttons to be pressed over and over so there is little delay.
The game was unleashed to the visitors of comic con, it was a hit. People loved playing it once they got going. We did kind of miss the other goal of making the game portable as it ended up a little big.
You can check out more f the photos from the build in our gallery.
Let’s go on a journey of repair with Jeffrey. We have a Dynatron radio model SRX 26. I think it’s from the 1970s. The radio came from Henry which has been in his family since it was new. Unfortunately it has been waiting on me to repair it since September 2020.
I started off by wiping all the dust I have let fall on it. It is a crazy heavy thing. The best way to start is to have a good look over the radio. The point is to find any problems with the cable and to check it is safe before ever plugging it in. It also seems to be missing its record player cartridge (the needle).
The radio lead and fuse are the next places to check. It is using an older style of plug that should be replaced at some point. The fuse and lead are fine. Now for a power-on test. the unit is not showing any signs of life.
Now to take it apart and show everyone’s favourite part the insides. There looks to be other historical repairs carried out. If you look at the above image on the left-hand side.
An internal mains fuse looks very “crusty”. After taking it out it’s clearly blown. There are also two more fuses that are blown. The type of fuse is nicely labelled on the radio but I had none in stock. A short walk down to RS and picked up a bag of replacement fuses.
It came alive! Well it turns on anyway. The next step to try and find some suitable audio leads to test the sound. I only had a headphone adaptor but soon was getting sound from the radio but with a lot of hisses.
To overcome the hiss, I attacked all the knobs with some switch cleaner. You take off all the knobs and spray in the fluid. Give the knobs a good turn, backwards and forwards to work in the cleaner.
The last job was to mount the speaker port that was loose in the cabinet. Unfortunately without that type of lead, I could not test it.
Check out the radio in action in the video above. The radio seems to work fine with headphones. The turntable needs a cartridge but that is a job for the radio owner. If you would like to see more photos of the repair check out our gallery.
Space is fun. Receiving data from space is even better. Below is a project built by our own Jeffrey Roe.
TinyGS is an open network of Ground Stations distributed around the world to receive and operate LoRa satellites, weather probes and other flying objects, using cheap and versatile modules.
The first step of the project is to load the software onto the TTGO LoRa32 V2. The TinyGS project provides a cross-platform flashing tool. It is then a very simple program to flash the firmware onto the microcontroller. The project then makes use of a Telegram bot to set up your station, issues you a username/password. If you wish to enable data transmission to the satellite you must have an amateur radio licence.
The main motivation for this project was to try out building my own antenna. A quarter-wave ground plane antenna is a great first project for people interested in radio. It requires only a small amount of tools. A youtube video from Andreas Spiess pushed me to think this was possible.
The first step of the antenna is to know the length of the radials(the bits on the side) and the monopole(the bit coming out the top). If you go along to this website, it has a handy calculator. We are trying to build a 433 Mhz for our purpose. I started out cutting up lengths of wire that I think is used for fencing. Sanding the ends of the wires to ensure an electrical connection.
Using the insides of terminal blocks, I connected the radials to an SMA Female Chassis Panel Mount. It made the build much easier. But the holes on the panel mount are just a little too small for the screws from the terminal blocks. I drilled them out a little to make enough room.
My brother helped to make a wooden plate and a little stand for the project. This allowed our outdoor testing as seen above. The next step was to bring the project outside and see would we receive any data. I was a bit unsure how the project would work out, so I had bought two units and one commercial antenna. The plan was to set them up in the back garden to test if my first antenna was up for the challenge of receiving data from a satellite in space.
The above photo shows both units in action. The unit on the right is our homemade antenna. They are on top of my washing line, held on with clamps in my back garden. It is in an urban back garden surrounded by houses. I had to wait around an hour for the first pass of a satellite.
The above is a side by side of the data received from both ground stations. The one on the left has the commercial antenna and the one on the right is my shiny new homemade antenna. I was very proud to see it working and even picked up an extra packet in the process. The data came from a CubeSat called Norby. You can read this paper about its build.
As darkness fell, so did the experiment end. Both units have now come into the house. I am still running my homemade unit on a windowsill until I get a chance to build an enclosure for it. Another task is to test out the antenna performance with a NanoVNA tool a member has loaned me. For more project photos check out our gallery. You can view the data the station is receiving online in real-time. https://tinygs.com/station/EI7IRB_2@747769602
If you are interested in taking up Amateur Radio as a hobby come along to this webinar. Amateur Radio – A Life Long Technical Hobby. A special Engineers Week event hosted by the Electronic and Computing division in Engineers Ireland and South Dublin Radio Club. It will feature me and Adrian Connor. Join us on March 10th.
