Wireless Humidity and Temperature Receiver Unit – Arduino

This is an easy-to-program magnetic rotary position sensor with high-resolution 12-bit analog or PWM output. This contactless system measures the absolute angle of a diametric magnetized on-axis magnet. The project is designed for contactless potentiometer applications and its robust design eliminates the influence of any homogenous external stray magnetic fields.  The industry-standard I²C interface supports simple user programming of non-volatile parameters without requiring a dedicated programmer. By default, the output represents a range from 0 to 360 degrees.  It is also possible to define a smaller range to the output by programming a zero angle (start position) and a maximum angle (stop position). The AS5600 is also equipped with a smart low-power mode feature to automatically reduce power consumption. An input pin (DIR) selects the polarity of the output with regard to rotation direction. If DIR is connected to the ground, the output value increases with clockwise rotation. If DIR is connected to VDD, the output value increases with counterclockwise rotation.

This sensor board provides frequency output as per relative humidity value. The project is based on a unique capacitive cell, this relative humidity sensor is designed for high volume, cost-sensitive applications such as office automation, automotive cabin air control, home appliances, and industrial process control systems. It is also useful in all applications where humidity compensation is needed. The circuit is built using a low-cost NE555 timer as an astable generator, humidity sensor MK1 acts as a variable capacitor and is connected to the TRIG and THRES pin. Pin 7 is used as a short circuit pin for resistor R3. The HS1101LF equivalent capacitor is charged through R2, R3, and PR1 is set the threshold voltage (approximately 0.67Vcc) and discharged through R2 only to the trigger level (approximately 0.33Vcc) since R3 is shortened to the ground by pin 7. Since the charge and discharge of the sensor run through two different resistors, R2 and R3, the duty cycle is determined by the following formulas.

This is a simple Proportional, Integral (PI) temperature control amplifier. A complete thermoelectric cooler (TEC) controller can be created using this PI amplifier and OPA569 Power Op-Amp or other output amplifiers such as DRV591, DRV592 and DRV593. Proportional-integrator compensation is simpler to adjust and often provides an adequate thermal transient response to the TEC driver amplifiers. The project consists INA330 chip and OPA2340 OPAMP.  The INA330 provides thermistor excitation and generates an output voltage proportional to the difference in resistances applied to the inputs. OPA2340 is used to create the PI closed Loop.

You may have seen many light-sensitive switch circuits based on an LDR sensor. Usually, the sensitivity of the LDR based light sensor is poor. We wanted a very sensitive light switch hence we decided to make a circuit based on a light sensor rather than LDR. After a little research on the internet, we found the OPT101 light sensor chip which includes a photodiode and a transimpedance amplifier in one package. The OPT101 light sensor provides an analog voltage output linearly proportional to light intensity.

This airflow sensor consists of INA326 precision instrument amplifier, double 100uA REF200 current sources, and a REF3025 2.5V reference voltage chip. Airflow dynamics dictate how much the voltage will increase or decrease for a given airflow rate. Therefore, the relationship between temperature and flow rate would have to be established for a method such as this to be useable. Two IN4148 diodes are used to sense the temperature, Diode D3 should be in static air and Diode D2 should be installed in the airpath flow path. The circuit works with 5V_DC and draws a few mA of current. REF3025 provides an accurate reference voltage which is 2.5V. Temperature linearity is within a tenth of a degree. The airflow is correlated to the change in D2 voltage. D2’s junction temperature and voltage are related to the airflow. D2 and D3 should be in the same temperature environment.