Assembly Manual

Mat Schaffer edited this page Dec 28, 2017 · 52 revisions

bGeigie Nano Kit Assembly Instructions, Version 6b (revised April 2017)

Table of Contents

  1. Introduction
  2. Before You Start
    1. Warnings
    2. Tools You'll Need
    3. Sort and Check Parts
  3. Main Board (PCB)
    1. Small Components
      1. Resistors
      2. Headers and Breakouts
        1. Headers and Breakouts: Back
        2. Headers and Breakouts: Front
  4. iRover
    1. Triple-Connector
  5. Battery
  6. Pancake Sensor
  7. Plates and Screws
  8. Pelican Case
  9. Test Run and Diagnostics
    1. Counter Function
    2. SD Card
    3. GPS Lock
    4. Battery
  10. Mounting
  11. Notes


This manual provides instructions for assembling the Safecast bGeigie Nano Mobile Radiation Monitoring Device. We're happy to be able to deliver this high-performance Geiger counter with GPS logging and memory, which has been developed and field-tested by Safecast volunteers.

The kit is an excellent tool for DIY learning. Assembly can take as little as 3-4 hours, depending on your level of skill and experience with electronics. Beginners should allot approximately eight hours.

You can purchase a bGeigie nano kit at

Before You Start:

Note that the LND_7317 pancake sensor is very delicate. It has a thin mica covering on one face, inside of which there is a partial vacuum. The mica is easily punctured. Should this occur, it will damage the tube irreparably. We recommend that you leave the pancake sensor in the box until you're ready to attach it.

As with any project, take the time to prepare by gathering the necessary tools, clearing space, reading the manual, and turning off distractions before you start.


  • The temperature of the soldering iron should be about 200-350 degrees Celsius (400-650 degrees Fahrenheit).
  • Smoke from solder is dangerous for your health, so work in a well-ventilated area.
  • Wear safety glasses when cutting off leads.
  • Do not puncture the Li-Po battery.
  • Be gentle with the kit. Some of the components are fragile. For example, it's possible to inadvertently break the wire leads from the battery.

Tools You'll Need

  • Soldering iron or gun
  • Solder (60/40)
  • Screwdriver (small Phillips-head/plus)
  • Needle-nosed pliers
  • Nippers (for cutting component leads)
  • Double-sided foam tape
  • Clear acrylic nail polish (aka "nail top coat," without glitter)
  • 3.3V FTDI cable (e.g. TTL-232R-3V3)

Sort and Check Parts

The parts come in several smaller bags.

  1. Identify, count, and check the parts against the "kitting parts list," which should be included in the kit package.
  2. You can also check them against the three placement diagrams in this manual, relevant photos, and the Parts List wiki page.
  3. If parts are missing or damaged, please contact us at

Main Board (PCB)

Nearly all of the components attach to the main board (PCB). Consult the Large Parts, Small Parts, and Back Parts placement diagrams below for help with placing parts.

While we suggest starting with the components that lie close to the board before the taller ones, the order of assembly is partly a matter of preference. Similarly, some builders place all of the components first and then solder them, while others prefer to place and solder one component at a time.

  1. Because dirt and oils can inhibit the solder bonds, we recommend wiping both sides of the PCB with isopropyl alcohol first, using a lint-free cloth. Handle the PCB by the edges whenever possible, and avoid touching the surfaces of the board with your fingers.

  2. Start by attaching four black plastic standoffs to the main board. Insert them into the holes in the corners.

  3. At each corner, insert a 10mm standoff from the upper face of the board.

  4. Attach the corresponding 8mm standoff to each 10mm standoff from the bottom.

Small Components

All of the small components go on the main board. Place and solder them, nipping off the leads. Refer to the Small Parts Placement Guide for help with placing these components. You can secure most components in place before soldering them by bending the leads slightly outward; this will allow you to turn the PCB over to solder without the parts falling out.


The kit contains 11 resistors (of six types), as listed in the Small Parts Placement Guide.

Pay close attention to the color ID stripes as listed on the placement guide. (Be especially careful not to confuse the 4.7k resistor, which has a red stripe, with the 47k one, which has an orange stripe).

Double-check for correct placement against the diagram before you solder. If in doubt, measure the resistors with an ohm meter. Ask for help if you need it.

  1. Diode (D1)

    Be careful to orient this resistor correctly, in accordance with its polarity. The black stripe on one end of the small orange glass part should align with the small white stripe on the component's outline on the board.

  2. Capacitors (C1- C3)

    While the capacitors in the photo are blue, the ones in your kit may be another color. They have two leads. These capacitors have no polarity and can be inserted either way. Avoid bending the leads too far outward, which can split the capacitors in two.

  3. LEDs ("COUNT"; "LOG/ALARM")

    There are two LEDs, one blue (for "COUNT") and one red (for "LOG/ALARM"). In the photo, the "case" or "package" of the blue LED is blue, while the one for the red LED is clear. However, both may be clear in your kit, with the color indicated by marker pen. You can also try powering the LEDs up with a 3V battery to check.

    LEDs have polarity and must be oriented the proper way. One lead is longer than the other. The longer lead is the positive (+) lead. It goes in the hole marked "+" on the board. The side of the plastic case that's flattened is the negative (-) side. Take care not to overheat the LEDs when soldering. Placing a part that has polarity the wrong way is the most common mistake.

    3a. Place the blue LED in the "COUNT" spot 3b. Place the red LED in the "LOG/ALARM" spot

  4. Transistor (T1)

    Place the transistor in the "T1" spot. It has three leads, which you may need to spread slightly in order to make them fit. Mount the transistor so that its shape matches the corresponding shape on the board, with the flat side of the case aligned with the flat side of the diagram.

  1. Switches

    There are four switches. Some are labeled on the top panel, the PCB board, or on the component itself. (The labels will be more legible once you've built the Nano, the case is open, and the power is off.)

    1. Dual DIP Switch (SW1) The dual DIP switch dims the alarm indicators (i.e., turns the lights and sounds on or off; #1: Speaker "clicks" and small Blue LED “Count” blinks; #2: small Red LED “Log/Alarm”).

      1a. Place the switch in the "SW1" spot. It has four pins. Position the switch with the side labeled "ON" toward the top of board, aligned under the "SW1" label on the board. The switch must be oriented correctly in order for it to work. 2a. Solder the switch in place.

    2. Toggle Switch The toggle switch alternates between bGeigie and xGeigie modes. The label on the transparent top panel says "bq/m^2 uS/h", "log cpm".

      2a. Place the toggle switch above the rectangular outline between transistor "T1" and the blue "COUNT" LED. It has three leads, and a mounting clip with two pins. 2b. Solder them all in place.

    3. Shift Switch (S1) This is the power switch. 0 = "off," and 1 = "on."

      3a. Nip off the two pins on the aluminum case. 3b. Place the shift switch in spot "S1." The three leads go in the three center holes in the board; the two outer holes are unused. (You could try filing the aluminum case pins down enough to fit in these holes, but it's secure enough attached by just the three leads.) 3c. Solder the three leads in place.

    4. Push Button Switch The function of the push button switch is user assignable, optional, and not currently implemented. If you would like, you can write code to give it a custom function.

    NOTE: With switches that have two leads, it's helpful to bend the switch over for clearance, but switches that have four legs can easily fit in a vertical orientation (switch facing up).

    4a. Place the push button switch in the "Fn" spot (optional).

After you've installed all of the small components, the main board should look like this:

Headers and Breakouts:

Breakouts sometimes are called “daughter boards” or “shields.” They include The OLED display, the Arduino Fio, the GPS module, and the OpenLog memory unit. Each of these breakouts should come in its own small bag or package. The "headers" are long black components with pins or legs. They come in several types and lengths, several of which you will need to cut to the proper size. The headers are used to attach the breakouts to the board. The headers in the kit include everything you need for all of the breakouts. A nine-pin male header for the GPS module should be in the GPS module bag, and an eight-pin length male header should be included in the OLED bag.

Be careful when cutting the long headers to length. Refer to the Large Parts Placement Guide guide and the relevant photos in this Manual. We recommend using wire cutters, but it's also possible to cut them by scoring them with a knife and snapping them off.

Cut the long headers in the kit to length as follows:

  1. One 40-pin (or “leg”) length, straight, male header: Cut this into four pieces to mount the Arduino Fio (14-pin and eight-pin), the OpenLog memory unit (six-pin), and the GPS (nine-pin) if necessary (i.e., if you're unable to find a nine-pin length in the GPS module bag).

  2. One 20-pin length, male header: Cut four (x4) two-pin lengths from this row. You'll also need these for the Arduino FIO. (OPTIONAL: Cut one (1x) four-pin length for mounting an audio out jack, which will be attached on the back side of the main board).

  3. One 10-pin length, angled, male header: Cut a six-pin length, which will attach to the Arduino Fio and connect to an external cable for loading firmware. Cut a three-pin length from the remainder. You'll attach this to the back side of the board, as part of the triple-connector.

  4. One eight-pin length male header: You'll find one of these in the OLED bag, and an extra with the other parts. This header does not need to be cut; you'll use this as-is to mount the OLED.

  5. One eight-pin length, female header: This header also does not need to be cut; use this in conjunction with the male header above to mount the OLED.

  6. One three-pin length, female header: Use as-is for connecting the iRover cable to the triple-connector

The male headers have long pins on one side and short pins on the other. While they can usually be inserted either way, we advise orienting them so the short pins go in the holes on the main board and the long ones project above. This will allow you to solder the longer pins to the breakouts. To visualize the fit of the parts, study the relevant photos and diagrams, then do a few test fits. The breakout boards can usually be used as placement aids for the headers. We also advise soldering the pins at each end first, then checking the header for proper alignment before soldering the remaining pins.

NOTE: It's possible to either solder the headers to the main board first, and then to each of the breakouts, or attach them to the breakouts first and then to the main board. We've found it easier to attach them to the main board first. While the order of installation isn't critical, we recommend following the sequence weʼve laid out, due to the heights and placement of the breakouts.

Headers and Breakouts: Back Side

Although most of the headers and breakouts attach to the front of the main board, you'll attach the iRover connector ("triple-connector") to the back side (in addition to the audio out jack, if you're using one). The iRover connector connects three wire leads from the iRover sensor controller and HV (high voltage) supply board to the main board.

Caption: iRover connector, a.k.a. “triple-connector.”

  1. Solder a three-pin angled header to the bottom of the board, in the position labeled “JP1.” You must insert the three-pin connector from the underside of the main board, in the spot marked "JP1," and solder it from the upper side of the board. Note that this iRover connector must be attached before attaching the OpenLog, which fits right on the other side of the main board.

**OPTIONAL: Audio Out Jack **

The audio out jack connects an audio cable to an iPhone or another device.

  1. Solder a four-pin male header to the holes marked “audio out.” You'll need to insert the header from the back side and solder the short pins from the front face.
  2. Attach a thin piece of double-sided foam tape to the black plastic jack housing, and use it to hold the jack in place on the board. Double-check the orientation to make sure it matches the image shown in the photo.
  3. Solder the four header pins to the audio jack.
  4. The audio connector might bump against a few of the OLED breakout pins on the rear of the main board; we recommend snipping those pins off or filing them down.

Headers and Breakouts: Front Side

Caption: Location of the Fio on the PCB

  1. Arduino Fio

The Arduino Fio is a microcontroller board based on the Atmel AVR ATmega328P microcontroller. This is the "programmable brain" of the Nano.

NOTE: The Arduino Fio has a small switch on the bottom side which you should turn OFF before soldering!

  1. There are four pairs of holes in the main board labeled CHG, BATT, SW, and DTR-CTS. Place a two-pin male header in each of these holes. Be sure to install these before you solder the Fio to the board (it's common to forget to install these.)
  2. Place a 14-pin length of male header on the left side of the Fio outline on the main board.
  3. Place an eight-pin length of male header on the upper right side of the Fio outline. You can use the Fio itself as an alignment guide to position the headers on the board properly.
  4. Place a six-pin length of angled male header on the Fio itself, in the row of holes that begins with GNDBLK and ends with DTR GRN. Insert it from the top (you'll solder it from the bottom later; see photo). This header will be used to connect the Fio to a computer for programming.
  5. Solder the header pins to the top of the Fio, or wait until all the headers are in place to solder the breakouts.
  6. Make sure you seat the Fio far enough down the header pins to allow enough clearance so that the enclosure lid still closes after you install the Bluetooth module later on. The FTDI pins may also be difficult to use if this positioning is off.

Caption: Proper location of the angled male header on the Fio. Note that it's inserted from the top!

Caption: Using the Fio as an alignment guide for the headers.


Caption: Placement of the GPS

The Global Positioning System (GPS) receiver records latitude and longitude coordinates to precisely locate where a reading was taken.

  1. Place a nine-pin length of male header (which is included in the GPS module bag) into the holes at the top of the "GPS" spot on the main board.
  2. It's helpful to attach the GPS board with two 5mm stainless steel standoffs (long hex nuts) using two stainless steel screws and two nuts. These will help keep the header properly positioned while you solder it.
  3. Leaving the standoffs in place, solder the nine pins to the top of the GPS breakout.

NOTE: The GPS unit comes with an optional metal battery clip. We recommend setting it aside, rather than installing it, as it can cause problems with the device.


OpenLog writes the data to a micro-SD card.

  1. Place a six-pin length of male header into the six holes at the top of the "OPEN LOG" spot on the main board. The long pins should face up with the OpenLog breakout held flat against the foam tape on the board.
  2. Put foam tape on the main board, beneath the OpenLog. The tape will help secure it, and prevent the micro-SD card from accidentally being inserted into the space between the logger and the main board. Most importantly, it will insulate the metal face of the OpenLog from the pins of the three-pin angled connector attached to the bottom of the main board, and prevent it from shorting.
  3. Once you've secured the OpenLog with foam tape, solder the six pins of the header to the OpenLog from above (the other four holes remain unused).
  4. Insert the micro-SD card into the micro-SD slot with the card's gold terminals facing up. Gently push the card in until it clicks into place.

Caption: Three exposed pins must be insulated from the OpenLog.

Caption: It may take two to three layers of foam tape to cover the exposed pins and secure the OpenLog.

Caption: Placement of the OpenLog, in relation to the GPS breakout.

OLED Display

OLED stands for Organic Light-Emitting Diode.

  1. Solder the eight-pin female header to the holes on the main board at the top of the "LCD" spot (the leftmost one is marked DATA).
  2. Insert the long pins of an eight-pin male header (included with the OLED module) into the female header, and attach the OLED board to the main board using two 10mm stainless steel standoffs, screws, and nuts. Screw a nut to each standoff first before placing the display on top of them which brings the OLED to its proper height. Care is needed in attaching the remaining two nuts as not many threads of the standoff will protrude above the OLED then.
  3. Solder the eight-pin male header to the OLED board from the top. The display will be easily removable.

NOTE: If your kit came with a Monochrome 0.96" 128x64 OLED graphic display, the spacing of the mounting holes will be different. For this reason, you should skip the step in the build instructions related to installing the M2x10 metal standoffs on the PCB near the display. Putting these standoffs on the display will cause it not to fit. While the display won’t be bolted to the PCB, it will function normally without them.

Caption: The placement of the headers and standoffs for the OLED.

Caption: The placement of the OLED, using nuts.

Caption: Note that the nuts are used as spacers under the OLED.

Caption: The completed main board, front view (with the OLED display removed to show the components beneath it).

You may want to do a test power-up at this stage.


The iRover is the controller board and HV (high voltage) supply for the pancake sensor.


The triple-connector connects three wire leads from the iRover to the main board.

  1. Cut three wires to about 8cm length, and strip both ends to leave about 5mm exposed. Tin the ends with solder to make the next steps easier. (Asking for help from a “third hand” will make these steps easier.)

  1. Solder all three wires to the thin gold posts on the iRover. The colors of the wires may be different than the ones shown in the photo; the important thing is to keep track of which one is connected to the positive post, which to the negative, and which to the middle. Make sure theyʼre attached in the configuration shown in the picture. Bending the exposed end of the wire into a “U” shape and hooking it around the post will make the process easier.

  1. Cut a three-pin length of female header from a six-pin female header. Solder the other ends of the three wires to the header pins. Make sure the colors match the way you've attached them to the iRover.

  1. The three-pin female header will serve as a socket for connecting the wires to the triple-connector you attached to the back side of the main board earlier (labeled “JP1”). When you connect it, be sure to orient the wire colors correctly.

  2. Remove the paper backing from the middle acrylic plate and orient it as shown in the photo.

  3. Attach two 5mm stainless steel standoffs to the two small holes near the bottom of the plate (not the corner holes!). Attach them with stainless steel screws inserted from the back of the plate.

Caption: Left to right: Rear plate, middle plate, front plate.

Caption: The standoffs for the iRover attach to the middle acrylic plate.

  1. Position the iRover board on the standoffs and attach it with two nuts. Make sure the side of the iRover that has the label is facing up, and the thick red wire with the black connector is to the left.
  • We find it works best to attach the stainless-steel standoffs to the middle plate by inserting the screw post through the plate and attaching a nut from the rear. The iRover itself can be connected to the posts using the screws afterward. This makes it easier to adjust its position slightly if desired. [Note that the current photo shows it differently, with the nuts on top.]

Caption: A view of the iRover, as installed in the proper orientation.

  1. Attach the front plate (the one with the SAFECAST logo, which covers the front side of the main board). Insert plastic screws through the four holes in the corner to attach it to the black plastic standoffs. Use pliers to tighten all of the standoffs.

Caption: Most kits currently ship with the 1200 mAh battery shown in "A." Older kits used a larger 2000 mAh battery shown in "B."


The battery is lithium polymer (Li-Po, Li-Poly). Older kits shipped with a 2000mAh version (labeled "B" in the photo above), while newer kits use a smaller 1200mAh battery (labeled "A" in the photo).

Attention: the battery is encased in a mylar membrane. If punctured, the battery can be hazardous. Handle with care!

The battery's red and black wires may be reinforced with electrical insulation tape to prevent them from falling off or being pulled out.

  1. Charge the new battery completely.

    The percentage of battery charge appears on the start screen, and a graphic indicator displays at the bottom right during use. The PCB also has a white 'reflective' pad that displays its charge, which allows you to check the charge without turning the unit on.

    The 2000mAh battery gives over 40 hours of continuous use and is rated for over 300 recharging cycles. Recharging occurs through a cable that connects the mini-USB port on the bottom of the Fio and a USB on a computer (or a correctly rated mini-USB recharger).

    Caution: NEVER charge the Nano while the unit is ON. The Nano Power switch MUST be turned OFF before charging to avoid permanent damage to the charge circuit. (Do not connect a mini-USB cable from a powered-on USB source without first turning the power OFF on the Nano.) Replace a broken battery with one that has the same rating. If larger batteries are used, the Nano charge circuit may overheat.

  2. Attach the battery with foam tape. (We recommend doing a dry run of these steps before completing them.)

  1. Place the partly-assembled Nano face-down (with the back side of the main board facing up). Orient it as shown, so that the triple-connector is at the bottom.
  2. Cut the thin, protective plastic sheet to an appropriate size, and lay it on top of the main board to prevent the battery from accidental puncture.
  3. Place a few strips of the double-sided foam tape on the battery, as shown in the photo. Stick one side of the tape to the battery, but DO NOT peel the other side of the tape yet. Lay the battery on the main board, with the wires extending to the left.

  1. Test-fit the middle plate, using the black plastic corner standoffs for positioning. The iRover should be facing up. Make note of the position of the battery.
  2. When youʼre sure the battery will be positioned properly, remove the middle plate, peel the foam tape, and carefully put the middle plate back in place, sticking it to the battery. Make sure the thin, plastic protective sheet is between the battery and the circuit board. Push on the plate gently to get the tape to stick. Remove the plate and battery (which should be taped together) from over the circuit board, and press them together firmly to make the tape connection secure.

  1. Thread the wires for the triple-connector through the slot in the middle plate. Giving the wires a couple of twists first will make this easier. Connect the three-pin female header/socket to the triple-connector on the back of the main board. Make sure to orient it so that the red wire connects to the positive pin, the black to the negative, and the green is in the middle.
  2. Thread the battery cable down so it will be easy to connect it to the battery port on the Fio. But DO NOT connect the battery yet! (The Nano power switch is down, or off.)

  1. Attach the remaining black plastic standoffs to the corners of the middle plate and tighten them.
  2. Position the rear plate on the standoffs, but donʼt attach it yet. It will be used to help position the pancake sensor in the following step.

Pancake Sensor

The pancake sensor is very delicate. Keep it in the box until you're ready to install it. Take care to protect the sensor membrane during the assembly process! Store it face-down on a smooth surface or in the box between steps.

Once you've connected the pancake sensor to the battery, it will also present a slight electric shock risk. Be very careful about touching it, particularly at the iRover connection where the bare wire is soldered. Also be careful not to let the bare wire touch the silver metal connector.

Caption: this is how the sensor should look.

Caption: A wrecked sensor.

  • The sensor will also be attached to the middle place with double-sided foam tape. While the etched outline on the plate itself may be enough to help you position it accurately, we recommend that you do a test fit using the opening in the rear plate as a guide.
  1. Attach a couple of pieces of foam tape, either to the middle plate or to the bottom of the sensor, and drop the sensor into place.
  2. When youʼre sure you can do it accurately, peel the tape and drop it in place.
  3. Remove the rear plate in preparation for the next steps.

It's a good idea to cover the exposed silver metal of the sensor post with shrink tubing, electrical tape, or something else that can act as an insulator to help guard against electrical shock and shorts.

The sensor gets two connections to the iRover: the anode connection, which is the thick red wire with black connector, and the cathode connection, which is a thin, uninsulated silver wire. Unroll this carefully!

  1. Carefully bend the silver wire around the thick post that protrudes from the sensor, making sure that it doesnʼt touch the bare metal surface.
  2. Depending on the version, the iRover may have one of three kinds of attachment points for the cathode: a small wire loop, a small hole, or a metal bump. The photo shows the cathode wire soldered to a bump-type connector. If your iRover has a hole-type anode connection, it's better to try to insert the wire through it from the bottom. If it's pushed in from the top, it may accidentally puncture the battery.
  3. Push the black connector onto the metal post. It should have a tight friction fit.

  1. Attach the rear plate using four black plastic standoffs and nuts.

Sensor Cover:

The copper mesh cover should be attached to the pancake sensor so that it protects the membrane. We've found that a thin coat of clear acrylic nail polish carefully applied to the edge of the mesh works well as an adhesive. If necessary, you can easily remove it later with nail polish remover.

  1. Apply a thin coat of clear nail polish or "nail top coat" to the edge of the mesh, which is easier to handle than the sensor. Carefully position it on the sensor as shown in the photo, and press down on it lightly with your finger for a minute or so until the polish starts to set. Allow it to dry for about five minutes.

Plates and Screws

  1. Check all of the plates, standoffs, screws, and nuts to make sure they're in the proper locations. You can disassemble the components fairly easily, if necessary.

Caption: The front plate should have clear plastic screws.

Caption: The rear plate should have clear plastic nuts.

Pelican Case

The Pelican case is a standard Pelican Micro Case 1010 model. The manufacturer's logo label can be peeled off. Do not use acetone/solvents to remove the sticker glue, as it will react with the box and destroy it. The case has a removable rubber liner, which may be black, yellow, blue, or red.

  1. Cut a hole in this removable rubber liner to fit the pancake sensor, as follows:

1a. Use the opening in the rear plate as a hole-cutting template. Push it snugly into the rubber liner, and trace the circular opening with a pen, pencil, or thin marker. Remove the liner from the case before cutting the hole in the rubber liner.
  1. Use an X-ACTO, Olfa, or similar knife to cut the liner hole.

    As an alternative, you can use the following can cutter hack:

    Safecast community member Joe devised this hack to simplify cutting neat holes for the sensor in the rubber lining of the Pelican case. This method takes advantage of the fact that the sensor is almost exactly the same diameter as a standard aluminum drink can. To use this approach:

     * Remove the top face of the can, using a sturdy knife or another method (Joe uses a razor saw).
     * Sharpen the thick aluminum edge slightly, as shown in the photo. It doesn't have to be extremely sharp to work.
     * Place the rubber liner on a block of wood or similar surface, and use the rear acrylic plate (the one with the hole for the sensor) to gauge or mark the position of the hole. 
     * Align the can carefully, push down hard with your palm, and rotate it slowly a couple of times. 

    This method requires a bit of a knack, but it makes the best holes!

  2. Put the liner back into the plastic case, and gently but firmly insert the assembled bGeigie Nano into the liner. Check that the sensor is properly aligned with the opening in the liner (alternatively, place the Nano into the liner and insert them together into the case). It should be a very snug fit. Close the case. The clasp shuts tightly with a click.

  3. Eight clear, neoprene runners are provided in the kit. Place them on the four corners of the top and bottom sides of the case. While the runners are optional, they often make it easier to mount the device.

Congratulations, your Nano kit assembly is finished!

Here are a few additional options:

  • Strap(s) are also provided to make it easier to mount the Nano on a car or other vehicle.

  • An optional beta window can be made if desired.

  • An Apple audio cord is provided for iGeigie mode updates to online databases.

Test Run and Diagnostics

!! IMPORTANT: Make sure you're running the most recent firmware.

If you've just finished assembling the main board, including the breakouts, it's a good idea to do a test power-up. We recommend this because it's much easier to fix problems that might be due to misplaced or poorly-connected components before the unit is fully assembled. The same sequence can be used for diagnostics after the entire Nano is assembled.

Before connecting the battery:

  1. There is a small ON/OFF switch on the underside of the Fio. Make sure that it is in the OFF position. If you didn't do this before attaching the Fio, it's accessible on the assembled unit (though harder to reach). If this switch is in the ON position, the unit will power up as soon as the battery is connected, and power switch attached to the main board will not function.

    1a. Remove the SD card if you've previously inserted it.
    2a. Set the switches on the main board:
    i. DIP switch - both should be in the ON position
    ii. Toggle switch - While this can be in either position, we suggest moving it to the down position (log/cpm)
    iii. Slider switch (power) - OFF position

  2. Plug the battery connector to the Fio.

  3. Turn the power switch to ON.

What appears on the display may change with upgrades to the firmware. In general, the display should show:

* The splash screen, with the word SAFECAST  
* The welcome screen:  
    - Unit version number  
    - Unit ID number  
    - Battery charge level  
    - Mode indicator  
    - Alarm setting  
    - Customizable text string (useful for putting a name)  
* The main screen  
    - With the toggle switch in the down position (logging mode/CPM), (during a mid-assembly test, with the sensor not connected), the main screen should display:  
        - Left column: 0 CPM  0 uSv/hr  NO SD CARD (when the SD card is installed, this should display Date/time)  
        - Right column: Battery charge indicator  No GPS (probably, though in certain conditions it may lock quickly and show the number of GPS satellites it's receiving signals from)  ---m (height)  XXhXXm (elapsed time) 
    - With the toggle switch in the up position (Bqm2/uSv/h), the display should show:  
        - Only one column:  0uSv/hr  0CPM 0Bq/m2, alternating with Mx=0 (max reading since reset) Ds=0 (cumulative dose since reset)  NO SD CARD, etc, as above  
* Several LEDs should illuminate:  
    * The red power light should be glowing visibly glow beneath the upper end of the Fio  
    * A small red LED on the GPS breakout should blink
    * A small blue LED on the OpenLog light should blink 

This completes the basic test. The following steps describe additional tests.

Additional Tests

Counter Function

To test the counter function with the sensor disconnected, use a knife blade or other small piece of metal to make a brief connection between the plus and middle pins on the triple-connector. The blue COUNT LED should light up, the speaker should click softly, and the display should show counts each time the pins are touched.

If the blue LED doesn't blink, it was probably installed with the polarity reversed. Another possibility is that the polarity of the diode (D1) is wrong. Remove and solder those components again if necessary.

SD Card

  1. Because the SD card is only detected at startup, switch the power off first.
  2. Insert the SD card.
  3. When the unit powers up, a date/time reading should appear at the bottom of the left column (replacing NO SD CAD), but it will not be correct until the GPS has locked.

GPS Lock

Test the GPS lock by putting the unit near a window while it's powered on. After a few minutes, the "No GPS" indicator will change to indicate the number of satellites it has locked to (e.g., "4 [upcaret]"). A height reading should also appear (e.g., "3m"). Since firmware version 1.3.0, Nano initiates a GPS reset procedure when there's no SD card inserted at boot time. To test the GPS lock, make sure you've inserted the SD card first. See the bGeigie Nano Operational Manual for more information.


To test charging the battery, attach a mini-USB cable to the Fio, then to a computer or USB charger. A yellow charge light should glow visibly underneath the Fio. The light will go out when the battery is fully charged.


Mobile Sensor

When the Nano is mobile, the log mode display also shows height (m), distance traversed (km), and duration of measurement (hh:mm).


To mount the Nano in a car, close the window on the straps. Tie the straps to an interior anchor or inside bar, or hang them over the window. Tie the strap to an anchor, rather than relying on the window lock.


See the photos and YouTube video listed below to learn more about extra options for the bGeigie Nano (such as wireless capability, air quality sensors, and bicycle exercise sensors).

Helicopter Drone


To mount the Nano in the snow, see


Schematics are available in Eagle format in the Safecast GitHub repository.

CONGRATULATIONS! Report your build in the Devices discussion group. Help in Safecast efforts. Make good, safe use of this new tool. Enjoy!

P.S. - How long did your build take? Click on the photo for Peter Blakely's time-lapse video, "bGeigie Nano assembly in 2 min".

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