Author: saad caffeine

My first Meshtastic node in Singapore is a US$15 to US$45 LoRa board set to the SG_923 region, on the default LongFast channel, with an antenna placed high. This guide covers the rules, the hardware, the setup, and the mistakes one Geylang East gateway made so yours doesn’t.

The rules

Set the region to SG_923 and keep radiated power at or under 100 mW e.r.p.; no licence or approval is needed. IMDA’s short-range device spec (TS SRD, Issue 1 Rev 3, 2023) puts general-purpose devices like Meshtastic under item 30d.

Band	Max power	Conditions	Use it?
917–925 MHz (item 30d)	100 mW e.r.p. (20 dBm)	“Suitable mitigation techniques”	Yes: Meshtastic region SG_923
433–434 MHz	10 mW e.r.p.	10% duty cycle	Only with a 433 MHz board (EU_433); few people here use it
866–869 MHz	500 mW e.r.p.	Under review for refarming	No: EU_868 boards won’t talk to SG_923 nodes
902–928 MHz US plan	—	Overlaps mobile networks outside 917–925	No: never use the US region

• Power maths: e.r.p. counts the antenna. A board at 20 dBm with a 3 dBi antenna radiates about 21 dBm e.r.p. (20 + 3 − 2.15), a little over the limit. With a 3 dBi antenna, set TX power to 19 dBm; with a 5 dBi antenna, 17 dBm.
• Region decides who you hear. Nodes on different regions never hear each other, even through MQTT.
• Buy the right frequency. Pick the 915 or 923 MHz version of a board; 868 MHz hardware is tuned for the wrong band.

Choosing hardware

For a first node, buy a Heltec WiFi LoRa 32 (V3 or V4) if it will sit at home on WiFi, or a Seeed / Heltec nRF52 device if it will live on a battery. ESP32 boards have WiFi (needed for an MQTT gateway) but drain batteries in a day or two; nRF52 boards have no WiFi but run for days.

Device	Maker	Price (USD, list)	Chip	WiFi	Best for
WiFi LoRa 32 V3 / V4.3	Heltec	18–28	ESP32-S3	Yes	Home node, WiFi-to-MQTT gateway. Node 7430 is a V3
XIAO ESP32S3 + Wio-SX1262 kit	Seeed	about 13–16	ESP32-S3	Yes	Cheapest node; ships pre-flashed, no screen
Mesh Node T114	Heltec	18–34	nRF52840	No	Battery node with a screen
Wio Tracker L1 / L1 Pro	Seeed	28–43	nRF52840	No	Handheld with GPS, screen, solar input
SenseCAP Card Tracker T1000-E	Seeed	about 40	nRF52840	No	Pocket tracker, IP65, no screen
SenseCAP Solar Node P1 / P1 Pro	Seeed	70–90	nRF52840	No	Rooftop or corridor solar repeater

• Frequency: order the 915 MHz (or “863–928 MHz”) version. Shops in Singapore sometimes stock 868 MHz boards; avoid them.
• Heltec V4 transmits up to 28 dBm. With region SG_923 the firmware caps it lower, but check TX power after setup (see The rules) and use firmware 2.7.20 or later on a V4.
• Never power a board without its LoRa antenna attached: transmitting into nothing can damage the radio.
• Some Heltec boards won’t charge or power from a USB-C to USB-C cable (missing resistors). A USB-A to USB-C cable works (ndoo.sg).
• The stock antenna is the cheapest upgrade. A tuned 915 MHz dipole of 3 dBi, mounted high and vertical, beats any board swap. In HDB blocks, a corridor or window facing open space matters more than the board.

First setup

An hour gets you from box to a node others can hear. Do the steps in this order; region comes before anything else because nothing transmits until it is set.

1. Antenna on, then power. Screw the LoRa antenna on before the USB cable goes in.
2. Flash current firmware at flasher.meshtastic.org in Chrome or Edge, unless the board came pre-flashed and recent. Choose “full erase” on a second-hand or re-purposed board.
3. Pair the phone app (Meshtastic for Android or iOS) over Bluetooth, or use the web client at client.meshtastic.org over USB.
4. Set LoRa region to SG_923. Leave the preset on LongFast. Then set TX power for your antenna (The rules).
5. Name it. Long name and 4-character short name; neighbours see these, so a place-based name (“GeylangEast 7430”) helps them map the mesh.
6. Role: CLIENT. Leave it there unless the node sits somewhere high and always powered and you have talked to locals first; extra ROUTER nodes in a dense area make the mesh worse, not better.
7. Position: share it fuzzy. For a home node, set a fixed position and lower position precision on channel 0, so the map shows the neighbourhood, not your flat.
8. Back up the config once it works: meshtastic --export-config > my-node.yaml (Python CLI, pip install meshtastic). Keep that file private; it holds your WiFi password and channel keys.
9. Optional, for a home gateway: WiFi + MQTT. On ESP32 boards, turning WiFi on switches Bluetooth off, so finish phone setup first and use the web client or CLI after. Set the MQTT server, then switch uplink on for channel 0 (see the next section for why that matters).
10. Check you are heard. Send “hello” on LongFast and look for your node on a public map (Joining the Singapore mesh).

Lessons from node 7430

Node 7430 is a Heltec V3 in Geylang East that relays the mesh to a home server over WiFi and MQTT. It went silent while looking healthy: it heard five neighbours, was on WiFi, and logged in to its broker, but one switch was off. Every lesson below came from getting it back, in November 2026.

What you see	What was wrong	What fixed it
“My node vanished” from the app and the map	It had been renamed (“GOSH-gsh1” to “GeylangEast 7430”) and its WiFi hostname changed with it	Find a node by its ID, not its name. !433c7430 never changes: it is the end of the board’s MAC address (…74:30)
Node hears the mesh, but nothing arrives over MQTT	Channel 0 uplink was off. Editing settings in the app had reset it	After any settings change, check uplinkEnabled: true on channel 0. MQTT on is not enough
A CLI command says it worked, but the setting is unchanged	Over WiFi, the write was lost when the connection closed too soon	Write, wait about 20 s, disconnect, reconnect, and read the setting back. USB is more reliable than WiFi for changes
Config backup over WiFi times out	Full exports are slow over the TCP API	Take backups over USB
Broker log: disconnected: protocol error	Old firmware (2.5.x) against a newer broker; a likely mismatch, not confirmed	Keep firmware current; read the broker log first when packets stop
Topic changed from msh/... to msh/SG_923/...	The app now sets a regional MQTT root	Fine, as long as whatever reads the broker subscribes to msh/#
Reboot counter above 40,000	The board restarts on its own: weak USB supply or a crash loop	A solid 5 V 2 A supply and short cable; watch the counter for a day

The habits that would have caught it the same day:

• Diagnose read-only first. List USB ports, look the node up on the LAN (the Meshtastic API answers on TCP port 4403), and read the broker log before changing anything.
• Back up before every change, and keep the backups dated; comparing two of them shows what moved.
• Give the gateway’s server a fixed LAN address (a DHCP reservation in your router). The radio’s MQTT setting points at an IP, and a new IP silently cuts it off.
• Put a check on a schedule. A daily “did any packets arrive?” alert turns a silent failure into a message.

Joining the Singapore mesh

The mesh here is patchy: urban range is about 2 km between nodes without line of sight, and the clusters have gaps, so MQTT over the internet still links them. Join the chat first; locals know which rooftops and corridors carry traffic.

• Talk to people: the 9V1 Meshtastic Telegram group run by the LPWAN & IoT Interest Group Singapore (aligned with SARTS), which holds meetups; and the Singapore LPWAN Group listed on Meshtastic’s local groups page.
• Radio settings that match everyone else: region SG_923, preset LongFast, default channel 0, frequency slot left at its default. Node 7430 runs exactly this and hears five neighbours from Geylang East.
• MQTT for a gateway: the shared Malaysia/Singapore config uses the community server mqtt.lucifernet.com with root msh/SG_923. You can also point a gateway at your own broker, as node 7430 does, to log your area’s traffic.
• Privacy before you uplink: MQTT publishes your node’s messages and position to the public internet. The shared config sends full-precision position; lower position precision on channel 0 and in map reports if the node is at home.
• See yourself on a map: with map reporting on, your node appears on public maps such as meshmap.net within the hour.
• Be a good neighbour: CLIENT role unless asked otherwise, no spamming LongFast with test pings, and keep ROUTER or repeater roles for well-sited, always-on nodes agreed with the group.

Where your node can go next: CitizenQuack and PLANETAI

A Meshtastic node can carry more than chat: it can carry sensor readings to a place that acts on them. Node 7430 does exactly that for two Edible Makerspace projects.

• CitizenQuack SG puts environmental sensors inside 3D-printed creatures, mostly ducks, so air quality and humidity get a face people notice. The project started at the “Smart Citizen Meets Meshtastic” hackathon, and the Singapore duck’s live readings sit a few meters from node 7430.
• PLANETAI is a Fab City programme: one open machine per place that reads local conditions, suggests what to do, and records whether anyone acted. Edible Makerspace runs an unofficial Singapore node in alpha testing, fed by NEA data, the CitizenQuack kit, indoor sensors and node 7430 as its radio gateway.
• How the radio fits: a PLANETAI node runs its own MQTT broker, and one gateway radio passes what the mesh hears into it. LoRa sensor nodes (temperature, humidity, PM, CO2, water level) report over the mesh, and their readings are filed under the radio that measured them (PLANETAI radios docs).
• Run your own: the node software installs in a few minutes on a spare computer; check which machines it supports first (PLANETAI docs). Your first Meshtastic board from this guide can be its gateway.
• Or just add a sensor near us: if you are in the east of Singapore, a LoRa sensor node on SG_923 within range of Geylang East can report into the Singapore node. Get in touch through Edible Makerspace.

Sources

• IMDA TS SRD, Issue 1 Revision 3 (2023): band 917–925 MHz, item 30d
• Meshtastic in Singapore, ndoo.sg (Andrew Yong, updated May 2025)
• Getting Started with Meshtastic, SARTS and its slides (PDF)
• Meshtastic configuration for Malaysia and Singapore
• Meshtastic local groups
• Heltec Meshtastic products
• Seeed XIAO ESP32S3 & Wio-SX1262 kit wiki
• The Best Meshtastic Devices for Every Use Case (2026 Edition), Adrelien
• Node 7430’s own logs and configs, Geylang East, 5 November 2026

Smartphone webapp to help with reading values from an analog refractometer.

Progressive WebApp

Source: Github

Scope Mount: 3D printables, STL

They’re alive!

This will create a basic shape of a head with a sad expression. The head is created using a cylinder and a subtraction of another cylinder to create the depression in the forehead and around the eyes, which typically associated with a sad expression. The eyes are created using small cylinders and positioned in a sad position, and the mouth is created using a linear extrude of a polygon with a sad shape. You can adjust the dimensions, positioning, and shapes of the head and facial features to suit your needs and create your desired expression.

// Define the parameters for the head
$head_radius = 40;
$head_height = 60;
$eye_radius = 5;

// Create the head
translate([0,0,0]) {
  difference() {
    cylinder(h=$head_height, r=$head_radius, $fn=100);
    translate([-20,-20,$head_height/4]) {
      cylinder(h=$head_height/2, r=$head_radius-10, $fn=100);
    }
  }
  // Create the eyes
  translate([-25,-30,$head_height/2]) {
    cylinder(h=$eye_radius, r=$eye_radius, $fn=100);
  }
  translate([-15,-30,$head_height/2]) {
    cylinder(h=$eye_radius, r=$eye_radius, $fn=100);
  }
  // Create the mouth
  translate([-20,-40,$head_height/4]) {
    linear_extrude(height = 5) {
        polygon(points = [[-10,-10], [-5,0], [0,-10], [5,0], [10,-10]]);
    }
  }
}

Made from clothes-hangers, used PET bottles, aquarium hardware and other bits and bobs found in response to a caffeine fuelled 3AM bout of inspiration. The Caffeinator uses cold-water dripping on coffee grounds with the slow-infusion process to extract nearly twice as much caffeine from the coffee as other hot-water methods.

It makes the thing that makes conversation happen. Now you can make the thing that makes the thing that makes conversation happen.

Pulau Ubin Island in Singapore is known for its rustic island-off-the-island charm, biking, hiking, and little seafood places but it also contains a rich biodiversity and diverse habitats, making it a popular destination for citizen scientists and casual researchers looking to study and explore the natural world. Recently, a group of young scientists and researchers had the opportunity to visit the island on a field trip led by 40-year-old Saad, a self-proclaimed “geek” with a passion for all things science.

Saad, who has spent many years working in the tech industry, has always had a love for science and exploration. When he heard about the opportunity to lead a field trip to Pulau Ubin, he jumped at the chance to share his knowledge and enthusiasm with a new generation of scientists.

As the group traveled around the island, Saad led them on a hunt for tardigrades, small aquatic creatures also known as “water bears” that are known for their ability to withstand extreme conditions. The group searched for tardigrades in a variety of habitats and water sources, using various DIY scientific tools and techniques to collect and study their samples.

Throughout the trip, the young scientists and researchers discussed the significance of tardigrades and the role they play in the ecosystem. The group shared knowledge and experience, asking questions and thinking critically about their observations.

In the end, no tardigrades were directly observed however the field trip was a fun one, with the group discovering a wide variety of microscopic creatures in different habitats and water sources. For Saad, it was a chance to share his love of science with others and to be inspired by them to explore and discover the microscopic natural world around us.

3D Printed, RaspberryPi powered, OpenSource all the way!

The PUMA microscope is a revolutionary piece of scientific equipment that is poised to change the way we think about accessibility and affordability in the field of microscopy. At its core, the PUMA (which stands for “Printed Ultra-Microscope”) is a high-resolution, 3D-printed microscope that is designed to be assembled from low-cost components and open-source plans.

One of the most innovative aspects of the PUMA microscope is its use of 3D printing technology. By leveraging the power of 3D printing, the designers of the PUMA microscope were able to create a microscope that is both highly accurate and extremely affordable. The 3D-printed design allows for the creation of custom, high-precision parts that are otherwise difficult or impossible to manufacture using traditional methods.

But the benefits of the PUMA microscope go far beyond just its low cost and innovative design. The open-source nature of the project means that anyone, anywhere in the world, can access the plans and instructions needed to build their own PUMA microscope. This level of accessibility is truly game-changing, as it means that scientists and researchers in underfunded or resource-poor areas can now have access to the same level of equipment as their counterparts in more developed regions.

The potential impact of the PUMA microscope is truly staggering. By making high-quality microscopy more accessible and affordable, the PUMA microscope has the potential to democratize science and research, and to open up new avenues of exploration and discovery for scientists around the world. Whether you are a seasoned researcher or a student just starting out in the field, the PUMA microscope is a tool that you simply cannot afford to overlook.

In conclusion, the PUMA microscope is a truly innovative and exciting project that has the potential to change the way we think about accessibility and affordability in the field of microscopy. Whether you are a scientist, researcher, or simply someone who is interested in the world of science, the PUMA microscope is a project that is well worth keeping an eye on.

Repurpose high RPM server Hard Disk Drives into functional lab equipment

Ingredients to make one:

• Plastic enclosure: repurpose a similar sized mass produced container like a lunch-box
• 3D Printed Bowden Tube holder STL merged with a coupler you can customize to fit the drive you have on hand using the OpenSCAD file
• Electronic Speed Controller (ESC) module: repurposed from a broken drone, commonly available module for drone motors
• Arduino nano or similar microcontroller with a potentiometer to control RPM
• Optional: LCD display to show estimated RPM
• Optional: Infrared sensor to count and display accurate RPM
• USB power supply for the microcontroller, DC power supply for the servo. Be sure to use a common (-) negative if using two power sources.
• Follow wiring diagram from the source:
  https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0259886.g001

https://journals.plos.org/plosone/article/figure?id=10.1371/journal.pone.0259886.g001

See Also: Lab-in-a-backpack

Contact us if you’d like to collaborate and build this into a workable solution for a meaningful context.

Taking the SCOBY vegan leather idea to an extremely delicate level with making them (literally) paper-thin. It’s a delicate and time consuming process but the material is so much fun to work with! Transparent, breathable, extremely light, and yet surprisingly durable for its thickness (or lack thereof).

The dehydrated scoby lay before me, a barren wasteland of cracked and crumbled organic matter. Yet, as I examined its gnarled surface more closely, I began to see the potential for something greater.

Gently, I ran my fingers over the rough texture, feeling the bumps and grooves that spoke to the natural origins of this unusual material. It was rough and slightly spongy to the touch, with a unique, earthy aroma that hinted at its past life as a living organism.

But as I continued to explore the scoby, I couldn’t help but be struck by its innovative nature. For here was a material that was not only vegan and environmentally friendly, but also remarkably versatile.

With the right techniques, this dehydrated scoby could be transformed into a sleek, supple vegan leather, suitable for use in everything from fashion accessories to furniture upholstery. Its unique aesthetic and physical properties made it the perfect choice for artists and designers looking to push the boundaries of traditional materials and create something truly original.

As I continued to marvel at the possibilities of this remarkable substance, I couldn’t help but feel a sense of excitement and possibility. For in the hands of a skilled craftsman, this dehydrated scoby could become a canvas for artistic expression, a testament to the power of innovation and sustainability.

Fight the single-use plastic scourge! We feel the making of disposable plates and cutlery should be part of the food-prep for potluck parties and picnics. It’s simple enough, super good for the environment, and sciencey enough to get deliciously nerdy about it all.
Surely one person in the friend circle can cook up some utensils, literally?

Dehydrating various thicknesses of SCOBYs to explore material properties. Further exploring colours, textures, and water-resistant treatment options to augment intrinsic material properties for artistic and practical use cases.

So many SCOBYs to work with!

The use of a dehydrated scoby, or Symbiotic Culture of Bacteria and Yeast, to make vegan leather is a innovative approach to creating a sustainable and animal-free alternative to traditional leather. The scoby, which is commonly used in the production of fermented foods such as kombucha, is composed of a complex network of bacteria and yeast cells. When dehydrated and treated with a variety of chemicals and processes, the scoby can be transformed into a flexible and durable material with a leather-like appearance.

One of the key advantages of using a scoby to create vegan leather is its sustainability. The production of traditional leather requires the processing of animal hides, which can be resource-intensive and contribute to environmental degradation. In contrast, scobies are easily cultivated and can be grown on a wide range of substrates, including agricultural waste and renewable energy sources. This makes the production of scoby-based vegan leather a more environmentally-friendly alternative to traditional leather.

In addition to its sustainability, scoby-based vegan leather also has a number of aesthetic and physical properties that make it suitable for use in a variety of artistic and commercial applications. The material is highly resistant to water and UV light, making it suitable for use in outdoor applications. It is also easy to dye and can be embossed or printed on to create a range of textures and patterns.

Overall, the use of dehydrated scoby to create vegan leather is a highly innovative approach that offers a sustainable and animal-free alternative to traditional leather. Its unique aesthetic and physical properties make it suitable for use in a wide range of artistic and commercial applications, and its sustainability makes it an attractive option for those looking to reduce their environmental impact.

Using visible lasers to etch into edible materials to selectively caramelise areas that darken to imprint images and illustrations without the use of dyes or inks of any kind. Precision toasting.

The use of blue laser technology to etch patterns and images onto edible materials through selective caramelization is a highly innovative and creative approach to food science. By using laser technology to selectively caramelize specific areas of an edible material, it is possible to create intricate patterns and designs without the need for dyes or other artificial colorants. This not only offers a more natural and healthy alternative to traditional food coloring techniques, but also opens up a range of new possibilities for experimentation with flavor, texture, and aesthetics.

One of the key benefits of using blue laser technology to etch patterns onto edible materials is its high level of precision and control. The laser beam can be focused and directed with great accuracy, allowing for the creation of intricate and detailed designs. This makes it possible to create a wide range of patterns and images on a variety of edible materials, including bread, cookies, and chocolate.

In addition to its precision, the use of blue laser technology also offers a number of other benefits for food science experimentation. By selectively caramelizing specific areas of an edible material, it is possible to create a range of flavors and textures. For example, the caramelization process can be used to create a crunchy or crispy texture, or to enhance the sweetness or complexity of a food’s flavor. This offers a range of possibilities for experimentation with new and unique flavors and textures.

Overall, the use of blue laser technology to etch patterns and images onto edible materials through selective caramelization is a highly innovative and creative approach that offers a range of possibilities for food science experimentation. By eliminating the need for dyes and offering a range of possibilities for flavor, texture, and aesthetics, this approach has the potential to revolutionize the way we think about food and food presentation.