Hi,
Ni hao ma.....? Hehe...Just a lil mandarin to spice up the mood.....huhu. Okay, now for this week 5, I'm focusing on the construction of the LM35.
What is LM35
The LM35 series are precision integrated-circuit LM35 temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 sensor thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 sensor does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C sensor is rated for a -40° to +110°C range (-10° with improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package. The LM35D sensor is also available in an 8-lead surface mount small outline package and a plastic TO-220 package.
What is LM35
The LM35 series are precision integrated-circuit LM35 temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 sensor thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling. The LM35 sensor does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full -55 to +150°C temperature range. Low cost is assured by trimming and calibration at the wafer level. The LM35's low output impedance, linear output, and precise inherent calibration make interfacing to readout or control circuitry especially easy. It can be used with single power supplies, or with plus and minus supplies. As it draws only 60 µA from its supply, it has very low self-heating, less than 0.1°C in still air. The LM35 is rated to operate over a -55° to +150°C temperature range, while the LM35C sensor is rated for a -40° to +110°C range (-10° with improved accuracy). The LM35 series is available packaged in hermetic TO-46 transistor packages, while the LM35C, LM35CA, and LM35D are also available in the plastic TO-92 transistor package. The LM35D sensor is also available in an 8-lead surface mount small outline package and a plastic TO-220 package.
LM35 Sensor Circuit Schematic |
Figure 1: Schematic diagram for LM35
LM35 Sensor Pinouts and Packaging
Figure 2: LM35 pinouts
Implementation of LM35
I
did some research on the most appropriate and simplest form of circuit
to be used for this project. Below I have attached the schematic
diagrams of the circuits I will be using. As you can see below, the
temperature sensor circuit shows that the sensor is simply connected
straight to the conditioning circuit as in Figure 3.
The temperature sensor (LM35) is connected to the operational amplifier (LM358) in order to amplify the output signal received from the sensor. The output signal (labelled as signal in the diagram), will be connected to the input of the PIC main board.
The temperature sensor (LM35) is connected to the operational amplifier (LM358) in order to amplify the output signal received from the sensor. The output signal (labelled as signal in the diagram), will be connected to the input of the PIC main board.
Figure 3: Schematic diagram for the temperature sensor by using LM35
I've
mentioned from the previous post that I will be constructing the PCB
board for the temperature sensor and relay switch circuit. So, I went to
the Pasar Road again to purchase some components to begin making the
circuits.
First of all, after I've purchased the necessary components, I went to the lab to do some circuit constructing on the breadboard to see whether the circuit works or not. For this circuit, I'm using LM35 as the sensor and LM358, 5k variable resistor and 100k resistor for the conditioning circuit.
First of all, after I've purchased the necessary components, I went to the lab to do some circuit constructing on the breadboard to see whether the circuit works or not. For this circuit, I'm using LM35 as the sensor and LM358, 5k variable resistor and 100k resistor for the conditioning circuit.
Figure 4: Components use for the LM35 circuit
Figure 5: Soldering process
So,
here is the complete board for the temperature sensor circuit (Figure 6). The 3 pin sticking out will be connected to the PIC board, ground
and 5V supply.
Figure 6: Component placement on the temperature sensor PCB board
So, that's it for now...! Let's stop here..it's already lunch time. Gotta go now. Hope you enjoy this entry. Have a great day.! :) <3
Bye & XOXO
nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
Quote of the day...!!
I would not waste my life in friction when it could be turned into momentum. ~Frances Willard
uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
p/s: I really love purple..... :)
Regards,
Idriah Safriza :P
