RadMon Monitoring Kits

There are 3 models of kits described on this page. The first two are the RadMon monitoring kits that are standalone Geiger counters that send their readings to IOT sites on the internet.
The 3rd model - GK-WiFi - provides the same IOT capability in an add-on kit for the GK-B5, GK-Mini, and GK-Plus Geiger kits. 

RadMon and RadMon Plus Kits:
Please Note: These are not a traditional Geiger counters. There is no speaker for clicks, and fresh counts are displayed at five second intervals .Sleep mode can be turned off for continuous operation, but in general, the RadMon kits are designed as a stationary monitors that send their data to IOT sites. 
                  RadMon (basic)                                                 RadMon Plus
RadMon kits are dedicated to radiation monitoring. Unlike a typical Geiger counter, they are designed to continuously report their readings to free monitoring and IOT sites via your home WiFi network. They are generally used from a stationary outdoor location. 
These kits are based on the ESP8266 which provide the microprocessor and the WiFi connectivity. It's likely that these are the first kits to use this architecture for Geiger counters.
The kits connect directly to your GM tube and drive it with between 360 to 1000V. At a minimum they capture CPM, uSv/h and WiFi signal strength (RSSI) for transmission. They will also capture temperature, humidity, and barometric pressure if an optional BME280 sensor is used. 

After collecting the data, the kits connect to your WiFi network and send the data to the monitoring and IOT sites that you specify. The software provides support to connect to any or all of - radmon.org, ThingSpeak and MQTT Brokers. (These sites are also described at the bottom of this page.)

A count and sleep cycle keeps power usage to a minimum. During the count cycle HV is supplied to the tube and events are counted. At the end of the cycle the kit connects to WiFi and sends its readings.
Following the transmission, the RadMon will enter sleep mode. The power demand drops sharply. At the end of the sleep cycle the RadMon wakes up and repeats the cycles.

Solar powered . . .
With the addition of good solar cell, charger and battery, powering the RadMon only with solar power works quite well. With WiFi connectivity, this makes for a totally wireless platform. I have been running these on solar power for severial years with very good results. The Build and User guides (linked below) provide the power budget and a solar powered example for each kit type. Please note however, that due to the various solar components that could be used, I can't guarantee results.  

RadMon basic vs. RadMon Plus:

Everything mentioned above is common to both the RadMon basic and the RadMon Plus kits. So what is the difference?
Generally speaking, the RadMon basic kit is a lower priced kit that requires the user to configure the network and IOT site credentials within the software. This is done using the Arduino IDE. Complete instructions are provided for this, but familiarity with Arduino is highly recommended.
On the other hand, the RadMon Plus is configured with your web browser on your phone or notebook. (The RadMon Plus becomes an Access Point on your WiFi network.) The software is preloaded and does not need to be modified.
Other differences between the two are mainly the PCB used and options. The table below points out most of these, but if you are uncertain it's best to look at the Build and User Guide (below) for each.
 Feature RadMon basic RadMon Plus
 Configuration Parameters are set in the source code and uploaded.
(Requires Arduino IDE with the ESP8266 core.)
 Setup through your web browser - no programming required.
 PCB Smaller -  2.95” x 1.95” (~ 7.5 x 5 cm) - yellow
(Designed for a 85x58x33 mm waterproof case.)
I/O, aux pwr, and I2C display headers provided.
 Larger -  ~4" x 3" (~10.2 x 7.6 cm) - black
(Designed for a 115x90x55 mm waterproof case.)
I/O, aux pwr, and 3x I2C display and sensor headers provided.
 OLED Display Option ($6) - mounts above ESP8266. Included - dedicated mounting. 
 Build and User Guide RadMon Build and User GuideRadMon+ Build and User Guide
 Price $34 or $40 with OLED $49 with OLED

Other features . . .
  • When counting, the LED flashes and counts are displayed on the OLED if one is present. This provides a snapshot of the current readings every 5 seconds, and a final screen showing the data sent and which sites it was sent to.
  • Two pushbuttons are used to put the kit in HV adjust mode, configuration mode (RadMon Plus) and programming mode (RadMon basic). In HV adjust mode the high voltage is set with a pot and the voltage is shown on the display (and serial output).
  • A carrier board is used to hold the ESP8266 for ease of replacement, and all common I/O pins are broken out.

Like the GK-WiFi , RadMon data can be displayed in Google Charts after it has been sent to the ThingSpeak site for collection. A simple HTML page can be run from your web site so you can see your data from 
You can see live data from my RadMon Plus solar powered system here.

If you have a (free) Google Site you can also add Google Charts to your pages. They will get the data from your ThingSpeak feed. See the Example Data page for more information on this. 

Purchasing the RadMon basic kit:
  • The kit includes the ESP8266, carrier board, and all parts needed to make the board shown in the top left picture above. 
  • The BME280 sensor, GM tube, battery, case, and solar components are not supplied.
  • An OLED display can be purchased along with the kit as an option.
  • The RadMon basic kit requires that you be prepared to upload your modified sketch to the ESP8266 with the Arduino IDE after you have added your network and site credentials. Step by step instructions for this are provided in the Build Instructions, but I do not recommend this kit to those with no programming experience.
  • Kits are available for purchase on the "Buy the Kit" page.
The Build Instructions and User Guide for the current v1.2 board with v1.6 software are here.

Purchasing the RadMon Plus kit:
  • The kit includes the ESP8266, carrier board, and all parts needed to make the board shown in the top right picture above. 
  • The BME280, GM tube, battery, case, and solar components are not supplied.
  • An OLED display is included with the kit.
  • Kits are available for purchase on the "Buy the Kit" page.
 The Build Instructions and User Guide for the current v2.1 board with v2.5 software are here.

The GK-WiFi Kit:
The GK-WiFi kit is another good way to get your Geiger kit readings to web sites on the internet. The GK-WiFi attaches to any of the counter kits here - GK-B5, GK-Mini, and GK-Plus. The software provides support to send your data to Radmon.orgThingSpeak and MQTT brokers.  (These sites are described below.) 
The kit uses an ESP8266 SOC for WiFi connectivity and processing. The board connects directly into your kit's FTDI port and reads the serial data (CPM, Dose, Vcc). coming from the kit. It then connects via WiFi to the sites you specify in the software and sends those readings. Three status LEDs show network down, data available, and send OK.
The GK-WiFi kit was also designed so that it can serve as a development platform for the ESP8266. A carrier board is used to hold the ESP8266 for ease of replacement, all common I/O pins are broken out and the LEDs can be disabled. This chip is a lot of fun to work with with using the Arduino IDE add-on package.

The software also supports an optional BME280 sensor that captures temperature, humidity, and barometric pressure  and sends those in addition to Geiger readings. 

 An I2C OLED display can also be added. The software supports it to display the connection status, or it can be used for other developments.
The GK-WiFi is only 1.85” x 1.40” (~4.7 x 3.6 cm) and the kit includes everything you need hardware-wise to use it. 

Please Note: This kit requires that you be prepared to upload your modified sketch to the ESP8266 with the Arduino IDE after you add your network and site credentials. Step by step instructions for this are provided in the Build Instructions for doing this, but I'd hesitate to recommend this kit to those with no programming experience.

 For more detailed information, refer to the GK-WiFi Build Instructions  below.

Purchasing the GK-WiFi kit:
The kit includes the ESP8266 and carrier board, and all parts needed to make the board shown above. All GK kit types are supported - GK-B5, GK-Plus, and GKmini. The BME280 sensor, and I2C OLED options are not supplied.
Kits are available for purchase on the "Buy the Kit" page.

GK-WiFi Build Instructions:
The Build Instructions for the current v1.4 board with v1.6 software are here.
(Previous versions of the GK-WiFi Build Instructions may be found on the Archive Page. )

About radmon.org, ThingSpeak, and MQTT:
All three kits discussed on this page now support radmon.org, ThingSpeak, and MQTT.
(Sparkfun's IOT offering "Phant" was supported prior to October 2017.  However Sparkfun discontinued that site. Software support for MQTT brokers was added to replace Sparkfun's IOT site. )

Radmon.org is dedicated to radiation monitoring and has attracted a good group of users at this point. It uses a unique approach where the Geiger's output is collected at the PC which then sends it to the Radmon.org website. (Instructions for connecting the basic kit to the Radmon app on a PC are on the Graphing to a PC page.)

However, the  GK-WiFi and RadMon software connects directly to the Radmon.org site, so a PC is not required.

map on Radmon.org allows you to compare your readings with other's around the globe, and very nice set of graphs for your CPM data is provided. You can see my radmon.org feed from the RadMon-Plus here.


ThingSpeak is a free IOT site with nice graphs and features.  It can also interface to MATLAB, but I haven't tried it.

It's supported by the  GK-WiFi and RadMon software.


MQTT is not an actual IOT site, but rather it's a "lightweight messaging protocol for small sensors and mobile devices" (mqtt.org). With it, RadMon or GK-WiFi will send its data ('publish') to a MQTT 'broker' that you define. That data can be read ('subscribed to') by another device. Some MQTT brokers also have a web interface that will allow you to see the data that you are publishing. Adafruit IO is one of these, and is shown on the left.

You may wish to use other brokers besides Adafruit IO. When using a broker that does not have a "dashboard" or interface, you must use some other application to "subscribe" to your feed. 

  • I have made a "subscriber" ESP8266 sketch that subscribes to everything that RadMon+ sends to the broker. It outputs the values to serial, and optionally on an OLED. 
The diagram below may you understand how MQTT can be used.