AVT1960 Thermometer with Thermocouple and Alarm Instruction Manual
- June 9, 2024
- AVT
Table of Contents
1960 Thermometer with Thermocouple and Alarm
Instruction Manual
AVT1960 Thermometer with Thermocouple and Alarm
Thermocouples are used to measure temperature over a wide range. They are used in industry, laboratories, transport, measuring and control instrumentation, etc. It also happens that the measurement should activate an alarm signal if the temperature is not within the set range, which is an additional advantage of this thermometer.
Specifications
-
1×6 LCD display
-
accuracy of measurement: ±1…2°C
-
temperature measuring range: 0…1024°C
(included probe allows a maximum temperature of 400 °C to be measured) -
alarm for set measuring range
-
board size 35×116 mm
Circuit description
Schematic diagram of the thermometer is shown in Figure 1. Depending on the
abilities and needs, the circuit can be supplied with a DC voltage in the 8…15
V range. The voltage supplied to connector X1 via D1 diode is fed to
stabiliser US1, which supplies +5 V. The operation of the module is controlled
by the ATtiny2313 microcontroller, timed by an internal clock signal, or more
precisely by the program contained therein. To ensure error-free temperature
measurement, a specialised IC module with integrated cold-end compensation
from Maxim-Dallas MAX6675 is used, which has an SPI interface through which it
communicates with the microcontroller. Due to the module used, the
construction of the thermometer is extremely simple. The temperature
measurement module can measure temperature in the range 0…1024 °C. It is
designed to work with a K-type thermocouple sensor (chromel-alumel), which is
most commonly used in multimeters.
Probe included with this unit can measure up to 400°C, its cable length is 50
cm and the metal cap has an M6 thread. Typical measurement accuracy for
thermocouples is ±1…2°C, which exceeds the required accuracy for most
applications. Visualisation of the result is realised on a 1×6 LCD display. In
practice, for this type of application, a display with such a small number of
characters is ideal. Communication of the display with the microcontroller is
in 4-bit mode. The PR1 potentiometer is used to adjust the contrast of the
displayed characters, while the R2 resistor limits the current flowing through
the backlight diodes. For alarm settings, the thermometer is equipped with
buttons S1 and S2. The alarm is set pressing either button, with the upper
button increasing the temperature and the lower button decreasing it. Alarm
signal is a modulated sound generated by a buzzer.
Mounting and start-up
The module must be mounted on the double-sided PCB shown in Figure 2. Photograph showing the details of the components arrangement under the display and the module with the MAX6675 and thermocouple will facilitate assembly. Begin mounting by soldering resistors and other small components onto the board. The next step will be to mount the thermocouple module, which is fastened with an M2.5 screw with the nut between boards. This mounting aligns the heights of the angled goldpins of the module and the main board, thus allowing to sold them together. The display will be installed as the last component. Device mounted without any errors, with efficient components and using a programmed microcontroller, will work as soon as energized. You must only adjust the display contrast with the PR1 potentiometer. Each time it is activated, the display shows the screen as in Figure 3. The same screen and alarm signal will appear when a sensor is disconnected from the measuring module or becomes damaged. During normal operation, the screen in Figure 4 will be displayed with the measured temperature, while when one of the buttons is pressed, the screen will switch to the set limit temperature value which triggers an alarm (Figure 5).
List of components
Resistors:
R1:…………………………………………10 kΩ
R2:…………………………………………100 Ω
PR1: ………………….mounting potentiometer 10 kΩ
Capacitors:
C1-C3: ……………………………………100 μF
C4: ………………………………………….220 μF
C5: …………………………………………100 μF
Semiconductors:
D1:…………………………………………..1N4007
DISP1:……………………………………..LCD 1×6
US1: ……………………………………….7805
US2:……………………………………ATtiny2313
Other:
MOD1:…………………….MAX6675 + thermocouple K
S1, S2:……………………………..Microswitch
SG1: …………………………………..Buzzer 5V
X1:………………………………………ARK2/500
Mounting elements
AVT SPV reserves the right to make changes without prior notice.Installation
and connection of the appliance not in accordance with the instructions,
unauthorised modification of components and any structural alterations may
cause damage to the appliance and endanger persons using it. In such a case,
the manufacturer and its authorised representatives shall not be liable for
any damage arising directly or indirectly from the use or malfunction of the
product.
The self-assembly kits are intended for educational and demonstration purposes
only. They are not intended for use in commercial applications. If they are
used in such applications, the purchaser assumes all responsibility for
ensuring compliance with all regulations
This symbol means do not dispose of your product with your other household
waste. Instead, you should protect human health and the environment by handing
over your waste equipment to a designated collection point for the recycling
of waste electrical and electronic equipment.
https://serwis.avt.pl/manuals/AVT1960_EN.pdf
AVT SPV Sp. z o.o.
Leszczynowa 11 Street,
03-197 Warsaw, Poland
https://sklep.avt.pl/
References
Read User Manual Online (PDF format)
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