Category: Project

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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.    

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Lockdown Pinhole Photography

Keeping making during lockdown is important, so time to do some pinhole photography, which we’ve done before at TOG. It’s incredible what you can do with almost nothing….. just a can, a few bits and some photo paper. You can take amazing long exposure photos, like this 3 month long exposure complete with sun tracks.

If you’d like to have a go, we have a limited amount of photo paper available. Get in touch with us and we can post you a sheet.

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