Circuit helps turns ON the switch when temperature reaches to the set point, NTC used as temperature sensor. Circuit built using LM393/LM358, Supply Input 12v DC
INVERTING AMPLIFIER SCHEMATIC PCB CALCULATION USING TLV170
This design inverts the input signal, Vi, and applies a signal gain of –2V/V. The input signal typically comes from a low-impedance source because the input impedance of this circuit is determined by the input resistor, R3. The common-mode voltage of an inverting amplifier is equal to the voltage connected to the non-inverting node, which is ground in this design. D1 indicates the power, all connection can be done using CN1 header connector, Capacitors, Resistors, LEDs are SMD components size 0805. Op-Amp TLV170 from Texas Instruments.
D1=Power LED, CN1= 6 Pin male header connector
ViMIN=-7V, ViNMAX=7V, VoMIN=–14V, VoMAX=14V, F=3KHZ, V+=15V, V-=-15V
- Use the op amp in a linear operating region. Linear output swing is usually specified under the AOL test conditions. The common-mode voltage in this circuit does not vary with input voltage.
- The input impedance is determined by the input resistor. Make sure this value is large when compared to the source’s output impedance.
- Using high value resistors can degrade the phase margin of the circuit and introduce additional noise in the circuit.
- Avoid placing capacitive loads directly on the output of the amplifier to minimize stability issues.
- Small-signal bandwidth is determined by the noise gain (or non-inverting gain) and op amp gainbandwidth product (GBP). Additional filtering can be accomplished by adding a capacitor in parallel to R1. Adding a capacitor in parallel with R1 will also improve stability of the circuit if high value resistors are used.
- Large signal performance may be limited by slew rate. Therefore, check the maximum output swing versus frequency plot in the data sheet to minimize slew-induced distortion.
- For more information on op amp linear operating region, stability, slew-induced distortion, capacitive load drive, driving ADCs, and bandwidth please see the Design References section.
Application Courtesy of Texas Instruments
Window Comparator/Voltage Sensitive Switch TLV1701
This circuit utilizes two comparators in parallel to determine if a signal is between two reference voltages. If the signal is within the window, the output is high. If the signal level is outside of the window, the output is low. For this design, the reference voltages are generated from a single supply with voltage dividers.
This 5V single-supply window comparator utilizes a dual open-collector comparator and two trimmer potentiometer to set the window voltage. 2X TLV1701 was used in this design due to its low power consumption and open collector output, which allows the output to be pulled up as high as 36 V.
Example Circuit From Texas Instruments
Heat activated cooling fan controller ( Thermal Activated Cooling Fan Driver Circuit) is a simple project which operates a Brush-Less fan when the temperature in a particular area goes above a set point, when temperature return normal, fan automatically turns off. The project is built using LM358 Op-amp ( Use LM393 instead for good performance) , and LM35 temperature Sensor. Project required 12V DC supply and can drive 12V Fan. This project is useful in application like Heat sink temperature controller, PC, heat sensitive equipment, Power supply, Audio Amplifiers, Battery chargers, Oven.
The SMD SO8 LM35 used as temperature sensor, LM358 act as comparator provides high output when temperature rise above set point, high output drive the Fan trough driver transistor. The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature. Temperature sensing range 2 to 150 centigrade. LM35 provides output of 10mV/Centigrade.
NOTE : It is advisable to use LM393 Comparator instead of LM358 as it will provide better results.
- Supply 12V DC 1Amps
- Fan 12V DC , 500mA
- Range : 2 °C to 150 °C
- Open Collector Output
- It can drive PC fan
- Onboard preset to set the Fan trigger level
- Onboard Power LED
- Onboard Output LED
- Output Driver Transistor
- Header Connector for Supply and Fan
- PCB dimensions 59.85 mm x 12.70 mm
LM35 Temperature Sensor
The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device 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°C to 150°C temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low-output impedance, linear output, and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy. The device is used with single power supplies, or with plus and minus supplies. As the LM35 device draws only 60 µA from the supply, it has very low self-heating of less than 0.1°C in still air. The LM35 device is rated to operate over a −55°C to 150°C temperature range, while the LM35C device is rated for a −40°C to 110°C range (−10° with improved accuracy). The LM35-series devices are available packaged in hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices are available in the plastic TO-92 transistor package. The LM35D device is available in an 8-lead surface-mount small-outline package and a plastic TO-220 package.
These devices consist of two independent, high-gain frequency-compensated operational amplifiers designed to operate from a single supply or split supply over a wide range of voltages.
These devices consist of two independent voltage comparators that are designed to operate from a single power supply over a wide range of voltages. Operation from dual supplies also is possible as long as the difference between the two supplies is 2 V to 36 V, and VCC is at least 1.5 V more positive than the input common-mode voltage. Current drain is independent of the supply voltage. The outputs can be connected to other open-collector outputs to achieve wired-AND relationships.
LM293A devices are characterized for operation from −25°C to +85°C. The LM393 and LM393A devices are characterized for operation from 0°C to 70°C. The LM2903, LM2903V,
Clap Switch/Sound Activated Switch with Timer Using PIC12F683 Micro-Controller
Circuit’s works on 5V DC, Its trigger the relay on every two clap sound, and keep output high for 1 to 4 Seconds depending on jumper settings J1, J2.
On board Potentiometer provided for sensitivity adjust.
Relay output is NO/NC. On board Power LED and Output LED.
Two Channel Audio Signal Mixer Using LM358-BA4560 Op-Amp
- Supply 5V DC ( LM358)
- Supply 12V DC (BA4560)
- Standard Audio Signal Input
- On Board Preset For Gain Set
- Header Connector for Inputs, Output & DC Supply
DC Solid State Relay Using Mosfet & Optically Isolated Gate Driver With Current Feedback & Fault Output
DC solid state Relay build using optically isolated Mosfet gate driver & high current Mosfet, this relay also provides current feedback as voltage output and fault TTL voltage output when current goes above set point. Current feedback designed around op-amp as signal conditioning which measure the current across low ohm shunt resistor. On board preset (trimmer pot) to adjust the fault current set point. Normally current fault output is high TTL it goes low if fault condition occurs. Circuit available at www.twovolt.com
- DC Supply 90V DC Maximum
- Maximum Current Load 15Amps
- Fault Output Normaly High Goes Low When Over Current/Short Detected
- Current Feedback 200mV/1Amp
- Gate Driver Supply 15V DC
- Fault Output Normally High Goes when Over Current or Output Short