Category: Project

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Simon Button Game

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.

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A journey of repair – Dynatron SRX 26

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.

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Building a TinyGS Station

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.

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Casio SK-1 Repair

A story of repair by our member Jeffrey.

I do like the chance to repair things every now and again. It allows me to get away from coding and try something.

This Sunday I had a look at this broken Casio SK-1. A classic small sampling keyboard made by Casio from 1985.

https://en.wikipedia.org/wiki/Casio_SK-1

From the owner, they didn’t have a plug for it and it was no longer working with batteries and the last time they played it the sound was a bit off.

I got the unit to power up with an adjustable voltage supply but taking care of the odd centre pin negative configuration. It can certainly make noise.

Finding the service manual online, made opening it up fairly straightforward. I can see some type of liquid had stained the area around the battery compartment.
A good while cleaning contact points and spraying it with a load of compressed air it looked a lot better. Now testing with five AA batteries the unit came to life.

Now for the odd sound. It seems when the volume is about 40% and a few of the bass notes are played distortion comes to visit. Thinking it might be just the inbound speaker, a line out was plugged in and it had followed us there.


The demo mode and other instruments at higher volume seem to be free of this distortion. A visual inspection of the caps and parts on the board, I saw no immediate signs of damage.
I called it a day before reaching for the oscilloscope and began probing singles and that’s all the time on I had on a Sunday morning.  For more photos check out our gallery.

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Project: Fun with Smart Plugs and Tasmota

This project is by our member Jeffrey Roe and is about saying goodbye to the default firmware on this smart plug.

The project started with a request from an artist for a device to turn on/off up to eight devices that are mains powered with a custom timing sequence. I decided to try out smart plugs as they have come down in price. It would also save building a circuit of relays as I have done in the past. Most smart plugs come with a firmware that connects the device to a private server and requires the internet to control it. The use case called for this unit to be used without the internet.

After doing a bit of research, the open firmware Tasmota seemed to have all the features the project needed and would cut down on the need to code up something totally from scratch. To flash the new firmware, some devices allow this to be done wireless but most require soldering wires to the microcontroller. The ease of soldering the wires varies from device to device due to the placement of the chip. The soldering job can be much harder on some devices.

Wireless flashing seemed the easy way to go as it required no soldering, so I purchased two plugs that the internet said worked with the TUYA-CONVERT. I went for two AOFO 4AC + 4USB Power Strip plugs ( Model C379 ).

This is when the problems started.  After hours of work, getting PI ready, installing the flashing tool and nothing happens. It turns out the blog post that recommended this plug combination with using the flashing tool had a comment at the end of the post (Which I did not read before starting out). It warned people that a recent update by the manufacturer fixed the hole that allowed users to flash a new firmware over the air.

Plan B was now in operation and I knew a soldering iron would be involved. https://templates.blakadder.com/index.html is a great website with a list of devices that can be used with Tasmota, which pins to connect to, how to get access to the pins and the template to control all the features Unfortunately the two plugs I now had awkwardly required the chip to be completely removed in order to flash them.

Due to lockdown, all I had at home was a soldering iron, solder and solder braid. No desoldering tools. After some effort, I managed to desolder the chip and connect the five wires required to flash the chip. Using the great tool Tasmotizer, it is straightforward to flash the chip with the wires in place. You can even give the WiFi details and config template.

Then started the job of putting the chip back in the board, soldering it again and putting all the parts back together. With a quick test, all was back working but another plug was still left one to do. In the previous photo above, you might have noticed a black plastic cover on the board that covers each plug. That cover blocks access to a pin required to put the chip into flashing mode and hence the need for all this desoldering. The second time around I checked if I could remove this cover and to my surprise, it came off.

\o/. With the cover off I could just solder wires to all the pins and not remove the chip from the board. This speeded up the whole process and made flashing the chip much much easier. A few crocodile clips, an FTDI programmer and we were in business. Both plugs are now ready to be controlled via WiFi API call.

I have updated the page on https://templates.blakadder.com/aofo_C379.html so anyone else flashing these plugs can know about this shortcut.

The rest of the project involved adventures in writing code for esp32 & esp8266 and problems with WiFi but that is for another time.

If you would like to see more photos from the project check out our gallery.

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Engineering a Cleanroom Power Tool

This project has come about because of the need to use cordless power tools in a cleanroom. Large numbers of screws and fasteners need to be removed and reinstalled on equipment during preventative maintenance. The proposal is to use power tools to speed up the process and reduce operator fatigue. You might think that a brand new or well maintained power tool would not give off any airborne particles, but that’s not the case. Airborne particulates are a big problem in a cleanroom. They can damage equipment and ruin product.

There’s a huge range of cordless power tools available from all the big-name manufacturers that you know well. Testing some of these tools with a particle meter highlights the problem. Background airborne particle readings are zero, down to 0.1 micron.

When the tools are brought near the meter however, the results are off the scale. This is hardly surprising, given that these tools are not specifically designed to be cleanroom compatible. This particular tool was a reversible ratchet with a brushless motor, so the particles were not carbon dust from the motor brushes. They were more likely from bearings, grease, and the reversible ratchet head.

Having discussed with TOG members, the proposal is to build some kind of enclosure around a tool…. a second skin….. with a connection to a vacuum line. That way, any particulates generated by the tool get drawn away. The tool must still be usable obviously, so the enclosure cannot be so clunky as to make it hard to use. An enclosure or covering that is conformal & flexible rather than rigid might be best. It must not collapse under the suction force. Silicone rubber has been suggested and there are some suggestions around vacuum forming, heat shrinking, 3D printing and silicone molding. If you have any comments or suggestions, feel free to drop us a line.