In a laboratory is necessary to measure the temperature of liquids and not always are easily available the last technological gadgets or practical one.
This article describes very generally some characteristics, requirements and usage of the gadget to design, a thermometer to be used in a laboratory
Important ! This project is based on specific requirements. Is not meant to be a "universal laboratory thermometer" but rather an instrument with specific characteristics needed in a specific laboratory.
The idea is that it can become a starting base for similar lab thermometers.
So here this project trying to design and build quickly a thermometer suitable to be used in a laboratory : the TeirmiLab
Lets start with the name.
The name is invented taking the first part of the Irish translation of "thermometer" (teirmiméadar) and of course "Lab" does not need of explanation.
Why Irish ? Well, I liked the sound of the name. The beauty of globalization.
The idea is to have a versatile and flexible instrument, capable to collect temperatures with probes attached to the display unit, measuring the current temperature, the minimum one, the maximum and work optionally as data logger.
The TeirmiLab can be also connected to a network (enhanced version), adding the possibility to see the current measurement in real time over a browser and adding graphic capabilities, remote setting of the unit and so on.
On the market do exists a lot of thermometers for laboratory use, but one of the goal of the project is to create an open platform and a thus customizable one, without spending up to thousand dollars.
The precision of the TeirmiLab initially is set as the sensor used, the DS1820.
Lets start with the name.
The name is invented taking the first part of the Irish translation of "thermometer" (teirmiméadar) and of course "Lab" does not need of explanation.
Why Irish ? Well, I liked the sound of the name. The beauty of globalization.
The idea is to have a versatile and flexible instrument, capable to collect temperatures with probes attached to the display unit, measuring the current temperature, the minimum one, the maximum and work optionally as data logger.
The TeirmiLab can be also connected to a network (enhanced version), adding the possibility to see the current measurement in real time over a browser and adding graphic capabilities, remote setting of the unit and so on.
On the market do exists a lot of thermometers for laboratory use, but one of the goal of the project is to create an open platform and a thus customizable one, without spending up to thousand dollars.
The precision of the TeirmiLab initially is set as the sensor used, the DS1820.
Requirements
The TeirmiLab should be able to performs these functions (the list has no particular priority)
Basic
- minimal and intuitive user interface
- read one sensor. The sensor should be detachable to be able to change it or clean it
- display the temperature away from the sensor
- display the temperature in Celsius or Farheneit or Kelvin
- Alarm
- Capability to offset the reading locally (setup)
- Capability to set the alarm locally
Enhanced
- read more than one sensor
- display locally the min and max temperature
- data logger capability
- capability to store locally temperatures for an amount of time
- setting for the measurement interval
- setting for start and stop
- capability to transfer the log to a remote computer
- remote connection capability
- setting alarms
- offsetting a probe
- download log
- reset log
- remote display capability
- (optional) print results locally
- (optional) RFID reader for identification
Minimal and intuitive user interface
In a world of "apps" it is easy to forget that sometime is more important a practical approach rather than a fancy one.The user interface of the instrument is based on a "traditional" LCD display and few push-buttons.
No fancy touch screen with nice graphics.
A lab instrument needs to be first of all simple and immediate to use and sturdy, ANYBODY should be able to use it after 5 minutes and the tools itself must be capable to work in an hostile environments (spills, dirt, etc.)
Alarm
The TeirmiLab should have the capability to generate an alarm if a specific temperature is reached.The alarm can be visual (change color of the display for example), audio (buzzer) or web based (browser pop up).
Remote display from the sensor
The sensor should be detached from the main unit, i.e. connected via cable.The thermometer should be placed away (inches) from the source to measure so to easily locally display the temperature on a local display
Local settings
It must be possible to set locally some functionality, like setting an alarm or setting up an offset.So a mini keyboard with at least three pushbutton is necessary.
Alternatively is possible to use a rotary digital encoder with a pushbutton.
Keyboard/Keypad
Here a button requirements:
- Mode
The Mode button allows to change the state of the instrument.
There are 4 modes : - Run (default mode)
In this mode the temperature read from the sensor is displayed in real time (every second).
If the alarm is set, the display will show the normal temperature in Green and will switch in Red when the alarm is reached. - Measurement unit
By default the measurement unit is in Celsius.
Alternatively is possible to select Fahrenheit or Kelvin
The selection of the measurement unit automatically update the current values (alarm/offset) - Alarm Set
In this mode is possible to enter the alarm temperature, using other two pushbutton to increment or decrement such value - Offset Set
Some sensors can have an offset. This mode allows to add a value to the reading to offset the sensor. - Increment
The Increment button (+) allows to increment a value - Decrement
The Decrement button (-) allows to decrement a value
Digital Rotary Encoder
The pushbutton on the encode select the mode, then rotating the encoder clockwise will increase a value. Rotating the encoder counterclockwise will decrease a value.
- Mode
The push button allows to change the state of the instrument.
There are 4 modes : - Run (default mode)
In this mode the temperature read from the sensor is displayed in real time (every second).
If the alarm is set, the display will show the normal temperature in Green and will switch in Red when the alarm is reached. - Measurement unit
By default the measurement unit is in Celsius.
Alternatively is possible to select Fahrenheit or Kelvin
The selection of the measurement unit automatically update the current values (alarm/offset).
Rotating the encoder will change the selection - Alarm Set
In this mode is possible to enter the alarm temperature, rotate the encoder clockwise or counterclockwise to increase and decrease the alarm temperature - Offset Set
Some sensors can have an offset. This mode allows to add a value to the reading to offset the sensor. - Reset
This option reset the TeirmiLab in a known configuration - Unit used : Celsius
- Alarm disabled
- Alarm value = 0
- Offset = 0
- Setting
When in a specific mode, rotating the encoder clockwise or counterclockwise will change the selection.
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