The internet may not be there when you need it.

It's easy to take our communications infrastructure for granted, but the internet, phone, and electrical systems are more fragile than you may think. Hurricanes, tornadoes, and winter storms knock out power to huge regions on a regular basis, with large-scale repairs sometimes stretching to weeks. Even on a good day, these networks require constant monitoring and maintenance to keep working.

Sometimes there isn't enough bandwidth to go around. It's common to lose cell service when you're in a crowd because the network is overloaded. In a natural disaster, phone lines can get jammed as people check on loved ones. And many regions have no cell service at all.

Using the internet can also be risky. If you're trying to arrange an abortion in a fascist-run state, there's a real chance your online activity might be used against you. If you're attending a protest, simply connecting to the cell network creates metadata that confirms you were there.

It's good to have options, just in case.

Radio amateurs (a.k.a. hams) have been texting over the airwaves for decades, using APRS (Automatic Packet Reporting System). But getting a ham license requires taking a test, and encrypted communication is strictly forbidden on the ham bands.

LoRa (short for long range) is a radio modulation technique introduced in 2015 that makes it possible for low-power devices to send data over long distances, up to several miles.

This project also demonstrates how much you can do with low-power electronic communications. It's apparent that we need to shift to renewable energy in the coming years, but we can't sustainably manufacture enough solar panels and wind turbines to support the level of energy consumption we're used to in the U.S. and Europe.

What is LoRa?

LoRa is short for Long Range radio. This protocol ideal for low-speed data transmission like text chat. It can't be used to transmit pictures or videos.

LoRa implements chirp spread spectrum (CSS) modulation, meaning that it is robust to channel noise and resistant to multi-path fading, resulting in low interference.

How far can it transmit?

In a rural area with clear line-of-site for miles around the range of a LoRa node can be up to six miles (10kms)! However, in a city where there are lots of houses at the same level as you and your node, the range is more likely to be just one to three blocks.

What is a mesh network?

In order for nodes that are far away from each other to communicate, they will utilize nodes that are in between.

In the example shown above, Alice and Charlie are too far away from each other to send messages directly using a LoRa node. However, Bob is located between and within range of both of them and Bob's node passes the message on.

In a densely constructed city very high locations can still achieve long range. For this reason, it is more effective to install your device at a higher elevation. Installing the device in your second story window is better than the first floor, and leaving the device on the roof is better than both of those locations!

➡️ What is Meshtastic?

Meshtastic is an open source, off-grid, decentralized, mesh network built to run on affordable, low-power devices like the Heltec LoRa32 V3 that comes in the Meshtastic kit from Iffy Books.

What is a lithium-ion battery?

A lithium-ion battery is a lightweight, high-efficiency battery. It is more expensive than other types of batteries, but offers a high depth of discharge, lifespan, charging rate.

What is a charge controller?

A charge controller regulates the voltage and current from the solar panel to the battery and the load by controlling the charging rate. Without the charge controller, excess solar power from the panel could overcharge the battery.

➡️ What is a voltage regulator circuit?

A voltage regulator circuit stabilizes fluctuating inputs to a fixed output to prevent even the slight chance of overcharging. The MCP1700 is a low-dropout positive (incoming) voltage regulator. It consumes a fraction (1.6 µA) of what it can deliver (250 mA) leading to a longer battery life and is ideal for single lithium-ion batteries.

What is a decoupling capacitor?

A decoupling capacitor will help smooth out short-term voltage spikes found in noise in the power supplies. For example, if the voltage suddenly drops, it’ll have enough power to counter act this change. If the voltage suddenly increases, it’ll be able to absorb that power.

Now it's time to learn how to make your own!

Parts

Included in your kit:

• Heltec LoRa32 V3
• 6-Volt, 6-Watt monocrystalline solar panel
• TP4056 battery charger board
• Button-top 18650 lithium-ion battery
• 18650 battery clip
• MCP1700-3302E low-dropout (LDO) regulator
• 100uF electrolytic capacitor
• 100nF ceramic capacitor
• Perfboard
• SH1.25 port and plug connectors
• Barrel plug
• 3/32" heat shrink tubing (~2" long) x2
• Cable tie bases

Parts you'll need to provide yourself:

• Weatherproof enclosure (See the step titled “Choosing a waterproof enclosure)
• Brick (optional; for weighing down the enclosure)
• Electrical tape

You’ll also need the following tools and supplies.

• Soldering iron
• Lead-free solder
• Helping hands tool (optional, but makes things easier!)
• Wire strippers (or use wire cutters/scissors... even a knife will work in a pinch)
• Drill with bits that can drill through your weatherproof enclosure
• Heat gun (or hair dryer)
• That glue that seals the washer in place

➡️Building your node

» Solder battery clip wires to TP4056 battery charger

The battery clip and wires

The TP4056 battery charger

The soldering iron

The red wire from the battery will connect to the B+ soldering hole and the black wire will connect to the B- solder hole.

The red wire from the battery will connect to the B+ through hole and the black wire will connect to the B- through hole.

Clip the excess wire off the ends.

» Solder 20-gauge wire to TP4056 input

Find the the two-foot length of 20-gauge wire and strip one end.

The red wire will be in the through hole next to the +, and the black wire will be in the through hole on the other side of the USB connection. Clip off excess wire.

» Solder skinny wire to TP4056 output

The skinny wire

The red skinny wire will be connected to the OUT+ through hole and the black skinny wire will be connected to the OUT- through hole.

» Cover the TP4056 with electrical tape and heat shrink

Why? Heat shrink and electrical tape will help protect your soldered connections.

Use electrical tape to cover all of the soldered joints.

Then wrap the 1/2inch diameter heat shrink tubing around the TP4056.

In this picture there is a hole for the troubleshooting lights on the TP4056 to shine through. While this may make troubleshooting easier, it's not necessarily recommended, especially if you are installing this node outside.

» Heat the heat shrink

Using the heat gun or hair dryer, heat the heat shrink until the it molds around the TP4056.

Electrical tape around the edges since the heat shrink might not fully mold around the ends.

» Solder the voltage regulator components

Arrange your breadboard or perfboard with the connected holes in a vertical orientation. You will end up using five rows and three columns, as marked below.

Insert the ceramic capacitor with the numbers facing down into row 1. The left leg will be column 1 and the right in column 3.

Insert the electrolytic capacitor into row 2. One leg is longer than the other. The short leg goes in column 1 and the long leg into column 3.

The LDO will be inserted into row 3 with the flat side facing down. The legs will go into columns 1, 2 and 3.

This is what your perfboard will look like from the bottom.

After you solder all of the through holes, clip the extra wire.

» Solder the rest of the components to the perfboard

Solder the skinny wires from the TP4056 to row 4. The black wire goes into column 1 and the red wire into column 2.

Solder the SH1.25 connector wires to row 5. The black wire will go into column 1 and the red wire will go into column 3.

A side view of the completed assembly

» Alternate mounting option

If you plan to leave this outside, or just want a compact way to carry the components around, you will need to enclose the node in something waterproof. However, if you know you will only be using the node inside, you may wish to forgo the waterproof enclosure and mount all of the components to the rear of the solar panel.

If you choose to go this route, you can skip through the steps that pertain to the outdoor enclosure. Pick back up at the step called “Solder the power cable to the barrel connector”.

Remember, if you have access to a roof or tall outdoor space, this will give your node the best range!

» Drill a hole for the power cable in the weatherproof enclosure

There will be an unavoidable small hole in your weatherproof enclosure for the power line. Placing the hole on the bottom will hopefully keep rain from dripping into the hole and then the electronics. We will also be adding a weep hole to allow any water that does get in to leak out.

Depending on what your enclosure looks like you may want to change the placement of the holes.

Drill a small hole in the enclosure for the power wire. This should be around 1/4”.

» Drill a hole for the antenna in the enclosure

If you are using an ammunition box as your enclosure, the best place for the antenna hole will be on the lid close to the hinge.

You can also place your antenna inside of the enclosure, but it is weatherproof and mounting it outside may give you more range.

Use a 1/4” drill bit and drill a hole for the antenna.

» Drill a weep hole in the bottom of the enclosure

Drill a small 1/8” hole in the bottom of the enclosure to serve as a weep hole. Place it on the opposite side of the enclosure than the power cable hole. This will allow any water that gets in to the enclosure to leak out.

» Run the power cable through the bottom

Run the thick power wire through the 1/4” hole at the bottom of the enclosure.

After doing so, use this glue to seal the hole and cover it in duct tape.

» Solder the power cable to the barrel connector

Before you solder, slip the thinner heat shrink around one red cable, one black cable, and then slip the thicker heat shrink around one pair of wires. This will mean each connection is protected by its own heat shrink but also by the larger heat shrink around it!

Solder the power wire to barrel connector. Match up the red wire and the black wires!

» Heat shrink the power cable

Use a heat gun or hair dryer to shrink the heat shrink to the wires.

» Solder the SH1.25 port to the LoRa32

To power your LoRa32 at 3.3V (instead of 5V via the USB-C port), you’ll need to solder wires to the pin holes labeled 3V3 and GND. Connect the red wire on an SH1.25 connector to 3V3 and the black wire to GND.

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» Arrange the components within the enclosure

Choose a location in your enclosure for your LoRa32. Find a cable tie base, remove the paper from the back, and press it down where you want the LoRa32 to go.

Secure the board with a cable tie and trim off the end.

Use a cable tie and base to attach your voltage regulator board.

Thread the antenna through the hole in the top of the enclosure and use the bottom nut to secure it. If you have a washer with a large surface area you can also seal the washer in place with glue.

Connect the antenna cable to the LoRa32 in the spot where the green square is in the previous picture.

Use a cable tie and base to attach your voltage regulator board

Attach the TP4056 the same way.

Use a command strip to attach the battery clip.

» Connect power

Insert the battery into the clip (make sure the + side on the battery matches the + side on the clip!).

Connect the barrel plug to the barrel plug end on the solar panel.

» Your node should power on!