Counter:
can detect α, β and γ ionizing radiation.
simultaneously displays the Count Per Minute (CPM) and equivalent dose rate of radiation in μSv/h on the LCD display.
indicates detection of ionizing particles with clicking sound and flashes of the yellow LED. (has a jumper for disconnecting-muting the buzzer);
has a TTL-serial connector for connection to a computer (more information on connection to computer - below);
when connected to computer counter outputs CPM, μSv/h and power voltage data in one minute intervals;
a threshold LED lights up when preprogrammed threshold in Counts Per Minute (CPM) are exceeded.
"mpde" Push-button is used for initial threshold value setup and change of the display modes (screens) - please reed more about that below in the Software functionality description section.
LCD display
LCD display is a 2 Line x 16 character backlit display. You can choose either Black-on-Green (default) or White-on-Blue LCD display. Please contact me by message is you prefer White-on-Blue LCD installed.
Powering the Geiger
Counter is designed to be powered from 9V battery when not connected to the computer.
It is recommended to buy a quality 6LR61 type battery.
If one desires, the whole circuit can be powered also from a 3 AA or 3 AAA batteries connected in series or 4 rechargeable batteries (rechargeable batteries are 1.2V) as circuit is actually operating at ~ 5V and there is a voltage regulator which steps down the voltage from 9 V to 5.
If you want to power the kit with lower voltage batteries 1,2 to 4,8 V please inquire. I have some step-up converters in stock.
When connected to computer (TTLSerial<>USB converter which is not a part of this listing is needed), counter can be powered throughout the TTL-Serial header and draw power from the computer.
Power consumption
With the LCD backlight being Off device draws 15 mA from the 9V battery. With LCD backlight fully ON total current drawn is around 44mA however with the 10K LCD brightness trimmer power draw can be reduced up to 18mA.
When using Tone mode, power draw can peak to 75 - 100 mA.
Connecting to a computer
Circuit has a TTL-serial connector (the 90 degree bent header) this is a serial connector, however it operates at Transistor to Transistor Voltage levels and can be connected to the computer through appropriate ttl-com port or ttl-usb adapter (TTLSerial<>USB converter which is not a part of this listing is needed). When connected to computer Counter can be a) powered from the computer b) simultaneously outputs to the standard serial terminal CPM, μSv/h and power voltage data in one minute intervals.
Software
The Software for the Counter is open-source (please ask if you need/want it in the file), developed in Arduino.cc Integrated Development Environment (IDE), which is very easy to grasp even for non-pros compared to programming in C. Therefore this counter is also good opportunity to learn about micro-controllers and change the software to your taste.
Version v.11.0.2 features:
Alarm threshold settable at power-on (retained in eeprom). Eeprom can be reset to default values by holding the "Mode" button during boot.
Alternate display (by press of the button)
A "quick response" bar graph (search aid)
Tone mode (radioactive source search aid)
Alarm (optional): When the CPM exceeds a preset value, the red threshold LED shall be lit.When the CPM drops back under the initially preset alarm threshold the LED whale go off.
The alarm threshold is configured during power up. After the first few screens you will see a "Set Alarm" prompt. To preset the alarm you have to use a push button or simply let the preset function time out (in 3 sec. of inactivity) to keep the then current setting.
Pushing the button point shall start a list of alarm settings. Push the button (or hold it down) until you find the desired setting, then release the button to set that last value. After the 600 CPM setting, the choices repeat. The possible settings increment by 10 until 100 CPM and then by 50 until the 600 CPM setting. There is also a "No Alarm" setting. The chosen setting is retained in eeprom so it does not need to be set each time.
Second Screen:
The same push button used to set the alarm is used to turn on or off the second screen. The chosen screen stays on until the button is pushed again. The first time the screen is entered, the totals will begin to accumulate from zero. After accumulation has started, reentering the mode will display the totals that have accumulated.
The second screen shows values for 1 minute and 10 minute periods. While the period is in progress (time not reached) the accumulated counts for the period are displayed. (On the 10 minute line, the elapsed time is also shown on the right side.) When a given period is complete, the format of the display changes . It then becomes the running average of CPM and uSv/h for the last 1 minute and 10 minute periods. The second screen is updated every 5 seconds.
Bar Graph:
The bar graph on the first screen shows quick changes in counts to make it easier to spot trends when surveying. It has a sample rate of 1/20 of a second.
by default Output is configured for Radiation logger software
note: TTLSerial<>USB converter which is not a part of this listing is needed.
Convenience features:
- LCD backlight is now switchable On or Off by double-clicking the "MODE" button;
- sound is now also switchable On or Off by double-clicking the "TONE-ZEROING" button;
- switching between the "Primary" and "Secondary" conversion rates is now done by long-pressing the "TONE-ZEROING" button with an few seconds indication of which rate is chosen on the LCD;
- additional potentiometer is installed to reduce the brightness of the LCD backlight (which provides essential battery power savings);
This adapted firmware version contains multiple other features present in original v.11.0.1 Please refer to the DIYGeigerCounter project site for details.
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Dimensions
PCB 42.5mm(1.673in) x 92.9mm(3.658in) x 21.7mm(0.854in)
LCD 35.6mm(1.4in) x 78.7mm(3.1in) x 10.2mm(0.4in)
