I was given one of these as a Christmas gift. Since I did not buy it, I can't leave a review. This comment is my review.

In short, this is a capable and easy to integrate sensor for long-term background radiation monitoring.

My use case is this sensor connected to an ESP8266 monitoring background radiation in my home and publishing the data to InfluxDB. The sensor has 4 pins, 2 for power one for signal and one for noise/movement alerts. It does not need a library or fancy code; the signal pin goes LOW every time it senses a gamma ray. A simple interrupt based routine that counts these events is all that is needed. I count events for 6 minutes at a time then convert CPM to micro sieverts. I have found that the conversion factor included in the sample code is not accurate, at least for my unit. I have run multiple concurrent tests of 5, 10 & 60 minute counts against my very accurate Mazur Instruments radiation monitor that uses a high quality GM tube. The typical background radiation at my house is very steady at 0.12-0.16 uSv/Hr. This unit (using the supplied conversion factor) is always very low at 0.02-0.05 uSv/Hr. I simply ran this sensor for a day and collected data, then compared to the same time period on my GM based device and calculated a more reasonable conversion factor. It's been running for several days now and is working very well. This is a great sensor for this kind of use case. Very happy with it. As others point out below and in the reviews, this is NOT a fast response device, it needs several minutes to get an accurate count.

I feel compelled to add to this blog since there seems to be a lot of confusion about this sensor and several of the negative reviews are not justified in my opinion.

This product (Pocket Geiger Radiation Sensor - Type 5) is built around the X100-7 ionizing radiation detector from First Sensor AG. The X100-7 is a high-quality and very stable solid state PIN diode detector with a large surface area. Similar versions of this detector have been used in several of NASA's x-ray telescopes.

The great thing about this detector is that its response does not depend on a carefully-regulated high voltage potential the way that a Gieger-Muller tube does. On the other hand, the X100-7 has an approximately 2 minute response time, so radiation detection IS NOT INSTANTANEOUS as it is with Gieger-Muller tubes. This later fact leads to many misunderstandings. This is not the sensor you want to use if you are prospecting for uranium because the response time is too slow. But if you want to accurately measure how much cesium-137 has contaminated the environment after a reactor accident, for example, then this is exactly the sensor you want. That's why thousands of these same sensors are in use in Japan today.

This sensor can detect gamma radiation and, if the included copper shield plates are removed, beta radiation. It cannot detect alpha radiation, since alpha is easily blocked by something as thin as a sheet of paper and it cannot penetrate the thin copper foil that is integral to the sensor. The X100-7 is quite sensitive; I have used mine to detect the decay of naturally occurring potassium-40 in bananas.

An Arduino library is available if you go to the Library Manager in the Arduino IDE and search for "RadiationWatch". This library is also available here: https://github.com/MonsieurV/ArduinoPocketGeiger (disclosure: I worked on the original version of this library which was derived from the sample code).

This is one of my favorite sensors.

Here's an open driver: https://github.com/tricorderproject/arducordermini/tree/master/firmware/examples/radiation_type5_example

The Arducorder mini, a handheld multisensor device, that includes a backpack board to make the Radiation Watch Type 5 more sensitive. Some of the posts also show histograms of pulse widths from this sensor, that appear to contain some energy-level information: https://hackaday.io/project/1395-open-source-science-tricorder

OpenCT, an extremely low resolution scanner using this sensor and a radioisotope source: http://www.tricorderproject.org/blog/dr-jansen-or-how-i-stopped-worrying-and-learned-to-love-the-barium/

I put this together with an ESP8266 to wirelessly monitor my kid after a radio-iodine treatment. This all went together super quick and easy, highly recommended. I posted a full write-up of this project for anyone else wanting to build one at https://github.com/finderoffail/radiation_sensor

I like this sensor. Appears to work well with Arduino - particularly with interrupt based counter. The pulse width seems to encode photon energy. Calibrating now but initially matches background radiation.

So glad I got the email for this. The First Sensor pin diode is extremely accurate. I've tested it against an industrial gamma detector with a Cesium-137 source and they are very close.

A little disappointing straight out of the box...the incredibly long response time, using the included Arduino sketch, makes the sensor basically useless.

I have a small chunk of uranium ore to use for testing radiation detectors. It takes this sensor ~2.5 minutes to respond to the ore, slowly coming up from (about) the 3 cpm background to 600 cpm ore count. Likewise, when the sample is removed, it takes another 2.5 minutes to settle back to the background 3 cpm. I'm thinking the included sketch needs some work...

Also, the companion Windows C# program, PokegaMonitor, is limited. It only allows communications on serial COM1 through COM9. You'll have to edit and recompile the code to get it to work at other ports above COM9, like mine at COM11. Even at that, it has a very limited range - the ore sample sends it off the chart.

I'm curious what people are seeing for background CPM, and what samples people have found interesting when using this device? (I'm seeing about 3 CPM currently and am considering getting the Geiger test card from United Nuclear...)

I'm trying to understand the schematic. Can anyone point me to a data sheet for U4, which the schematic says is an LT1651? My search skills have come up short.

How durable is this sensor? Is this sensor durable enough for used on weather balloons or drones?

Hmm, to my knowledge the Type5 version cannot simply be connected to the phone via jack as stated in the video: http://radiation-watch.sakuraweb.com/share/type5_testpin_specification.pdf. But perhaps I am wrong?