Type K Thermocouple Sensor Amplifiers with Cold Junction Compensation Using AD595-AD594

The sensor project is based on AD595 IC from Analog devices.  AD595 is a complete instrumentation amplifier and thermo-couple cold junction compensator on a monolithic chip. It combines an ice point reference with a pre-calibrated amplifier to produce a high level (10 mV/°C) output directly from a thermo-couple signal. Pin-strapping options allow it to be used as a linear amplifier-compensator or as a switched output set point controller. It is amplify its compensation voltage directly, thereby converting it to a stand-alone Celsius transducer with a low impedance voltage output. The AD595 includes a thermo-couple failure alarm that indicates if one or both thermo-couple leads become open. The alarm output has a flexible format which includes TTL drive capability.

NOTE : Refer AD595 Data sheet for supply input and other information, The circuit works with single supply, same board also support AD594 IC which can support type J sensor.


  • Supply 15V DC
  • Supports Type K Thermocouples
  • Provides 10 mV/Centigrade

Download PDF Schematic


What is Thermocouple??

A thermocouple is an electrical device consisting of two dissimilar electrical conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature. Thermocouples are a widely used type of temperature sensor

What is Type K Thermocouple Sensor??

Type K Thermocouple (Nickel-Chromium / Nickel-Alumel): The type K is the most common type of thermocouple. It’s inexpensive, accurate, reliable, and has a wide temperature range. Type K thermocouples usually work in most applications as they are nickel based and exhibit good corrosion resistance. It is the most common sensor calibration type providing the widest operating temperature range. Due to its reliability and accuracy the Type K thermocouple is used extensively at temperatures up to 2300°F (1260°C). This type of thermocouple should be protected with a suitable metal or ceramic protection tube, especially in reducing atmospheres. In oxidizing atmospheres, such as electric furnaces, tube protection is not always necessary when other conditions are suitable; however, it is recommended for cleanliness and general mechanical protection. Type K will generally outlast Type J because the JP wire rapidly oxidizes, especially at higher temperatures.

Type K Thermocouple Range

  • Thermocouple grade wire, –454 to 2,300F (–270 to 1260C)
  • Extension wire, 32 to 392F (0 to 200C)


AD595 Output Voltages


Various Type K Temperature Sensors



Optical Reflective Line Sensor for Robotics and No Contact Surface Sensing QRE1113

The sensor circuit helps to sensing the line for robotics application and  no contact surface sensing. The mini line sensor provides analog voltage output and can work with 3.3V and 5V DC. Analog output voltage is proportional to IR reflected to the senor. Resistor R1 controls the current  to IR LED, R2 provided as pull up resistor. Sensor contains Infra-Red led and photo transistor detector.

Download PDF Schematic


Schematic Line Sensing Sensor QRE1113



PCB layout QRE1113 Optical Sensor




Pin Configuration

Quadrature Encoder to Clock and Direction Signal Converter Using LS7084/LS7184

The quadrature LS7084/LS7184 Module is a CMOS quadrature clock converter. Quadrature clocks derived from optical or magnetic encoders, when applied to the A and B inputs of the LS7084 are converted to strings of a Clock and an Up/down direction control. These outputs can be interfaced directly with standard Up/Down counters for direction and position sensing of the encoder.

J1 Jumper input selects between x1 and x4 modes of operation. A high level selects x4 mode and a low-level selects the x1 mode. In x4 mode, an output pulse is generated for every transition at either A or B input. In x1 mode, an output pulse is generated in one combined A/B input cycle.

Resistor R7-RBIAS (Pin 1) Input for external component connection. A resistor connected between this input and VSS adjusts the output clock pulse width (Tow). For proper operation, the output clock pulse width must be less than or equal to the A, B pulse separation (TOW £ TPS).



  • Supply 5V DC
  • +4.5V to +10V operation (VDD – VSS)
  • On Board Power LED
  • J1 Encoder pulse multiplication ( Jumper JL Close =1X, Jumper JH Close = X4)
  • Header Connector for Encoder Interface
  • X1 and X4 mode selection
  • Programmable output clock pulse width
  • On-chip filtering of inputs for optical or magnetic encoder applications.
  • TTL and CMOS compatible I/Os
  • Up to 16MHz output clock frequency


Note : Circuit uses LS7084 IC , which is CMOS IC and working voltage range 4.5V to 10V and it has two scale up  range.X1 and X4. The board can be used with LS7184 which can work with lower supply range 3.3V to 5V and it can provide X1,X2,X4 resolution, refer data sheet of LS7184 for more information.








Note: Check Graph for R7- Bias Selection





What is Quadrature Encoder?

The most common type of incremental encoder uses two output channels (A and B) to sense position. Using two code tracks with sectors positioned 90 degrees out of phase, the two output channels of the quadrature encoder indicate both position and direction of rotation. If A leads B, for example, the disk is rotating in a clockwise direction. If B leads A, then the disk is rotating in a counter-clockwise direction.

By monitoring both the number of pulses and the relative phase of signals A and B, you can track both the position and direction of rotation.

Some quadrature encoders also include a third output channel, called a zero or index or reference signal, which supplies a single pulse per revolution. This single pulse is used for precise determination of a reference position.

How Quadrature Encoder Works?

The code disk inside a quadrature encoder contains two tracks usually denoted Channel A and Channel B. These tracks or channels are coded ninety electrical degrees out of phase, as indicated in the image below, and this is the key design element that will provide the quadrature encoder its functionality. In applications where direction sensing is required, a controller can determine direction of movement based on the phase relationship between Channels A and B. As illustrated in the figure below, when the quadrature encoder is rotating in a clockwise direction its signal will show Channel A leading Channel B, and the reverse will happen when the quadrature encoder rotates counterclockwise.

Apart from direction, position can also be monitored with a quadrature encoder by producing another signal known as the “marker”, “index” or “Z channel”. This Z signal, produced once per complete revolution of the quadrature encoder, is often used to locate a specific position during a 360° revolution.

Magnetic Field Sensor With Linear Output Using AD22151

Magnetic field sensor project using AD22151 IC from Analog Devices, The AD22151 is linear magnetic field transducer. The sensor output is a voltage proportional to a magnetic field applied perpendicularly to the package top surface. The sensor combines integrated bulk Hall cell technology and instrument technology to minimize temperature related drifts associated with silicon Hall cell characteristics.


  • Supply 5V DC @ 25mA
  • Power Led On Board
  • Header connector for supply and output
  • Normal Output 1.800V
  • South side Magnet Output 4.800V
  • North side Magnet Output 0.042V


  • Throttle Position Sensing
  • Pedal Position Sensing
  • Suspension Position Sensing
  • Valve Position Sensing
  • Absolute Position Sensing
  • Proximity Sensing


Download PDF Schematic

Download Document

Download Datasheet AD22151

Video With Bar-Graph Display











Metal Detector Schematic and PCB layout Using TDA0161

The Metal detector project is designed for metallic body detection by sensing variations in high frequency Eddy current losses. Using an externally-tuned circuit, they act as oscillators. The output signal level is altered by an approaching metallic object. The output signal is determined by supply current changes. Independent of supply voltage, this current is high or low, according to the presence or absence of a closely located metallic object Between pins 3 and 7, the integrated circuit acts like a negative resistor with a value equal to that of the external resistor R3 and trimmer potentiometer PR1 (connected between pins 2 and 4). The oscillation stops when the tuned circuit loss resistance (Rp) becomes smaller than R3. As a result, ICC(close) = 10mA (pins 1 and 6). The oscillation is sustained when Rp is higher than R3, and ICC(remote) = 1mA (pins 1 and 6). Eddy currents induced by coil L1 in a metallic body determine the value of Rp.

  • Supply 5-12V DC
  • Output Normally High , Provide Low output in presence of Metal
  • LED Sensor Active Indicator
  • Sensing Distance 5-15mm

Download PDF Schematic & PCB Layout





MPXM2010GS 0 To 10kPa (0 To 1.45 PSI) Pressure Sensor Module

The MPXM2010GS silicon piezoresistive pressure sensors provide accurate and linear voltage output directly proportional to applied pressure. These sensors house a single monolithic silicon die with strain gauge and thin film resistor network integrated. The sensor is laser trimmed for precise span, offset calibration and temperature compensation. The series includes a strain gauge and thin-film resistor network integrated on each chip



  • Temperature Compensated over 0 to +85 C
  • 0 To 10kPa (0 to 1.45psi)
  • Output 25mV Full Scale
  • Supply 10V DC (10-16V Possible)


  • Respiratory Diagnostics
  • Air Movement Control
  • Controllers
  • Pressure Switching

This Details is from NXP Application AN1950

The resolution of the system is determined by the mm of water represented by each A/D count. As calculated above the system has a span of 226 counts to represent water level up to and including 40cm. Therefore, the resolution is:

Resolution=mm of water/Total # counts=400mm/127 counts=3.1 mm per A/D count


Bellow Schematic from NXP Application Note

Reflective Object Sensor- Infra Red Optical Proximity Switch Using PLL LM567

Reflective Object Sensor- Optical Proximity Switch Using PLL LM567

The simple circuit is based on LM567 PLL IC and optical sensor QRD1114 from Fairchild semiconductor. The QRD11114 reflective sensor consists of an infrared emitting diode and an NPN silicon photo Darlington mounted side by side in a black plastic housing. The on-axis radiation of the emitter and the on-axis response of the detector are both perpendicular to the face of the QRD1113/14. The photo Darlington responds to radiation emitted from the diode only when a reflective object or surface is in the field of view of the detector.

  • Supply 5V DC
  • Output LED
  • Output TTL 5V
  • Sensing Distance Up to 15MM
  • Sensing Distance Adjustable



Dual-Channel Quadrature Hall-Effect Bipolar Switch Module For Magnetic Encoder for Motion Control application.


Dual-Channel Quadrature Hall-Effect Bipolar Switch Module For  Magnetic Encoder for Motion Control application.

The A1230 is a dual-channel, bipolar switch with two Hall-effect sensing elements, each providing a separate digital output for speed and direction signal processing capability. The Hall elements are photolithographically aligned to better than 1 µm. Maintaining accurate mechanical location between the two active Hall elements eliminates the major manufacturing hurdle encountered in fine-pitch detection applications. The A1230 is a highly sensitive, temperature stable magnetic sensing device ideal for use in ring magnet based, speed and direction systems located in harsh automotive and industrial environments.


  • It Provides Dual A & B Channel Like optical Encoder
  • Simple Module help to make Magnetic Encoder for Motion Control application
  • Supply 5V DC
  • TTL Output
  • Two matched Hall-effect switches on a single substrate
  • 1 mm Hall element spacing
  • Superior temperature stability and industry-leading jitter performance through use of advanced   chopper stabilization topology
  • Integrated LDO regulator provides 3.3 V operation
  • Integrated ESD protection from outputs and VCC to ground
  • High-sensitivity switch points
  • Robust structure for EMC protection
  • Solid-state reliability
  • Reverse-battery protection on supply and both output pins


  • Brushless DC Motor Rotation
  • Speed Sensing
  • Pulse Counter
  • Magnetic Encoders




The A1230 monolithic integrated circuit (IC) contains two independent Hall-effect bipolar switches located 1 mm apart. The digital outputs are out of phase so that the outputs are in quadrature when interfaced with the proper ring magnet design. This allows easy processing of speed and direction signals. Extremely low-drift amplifiers guarantee symmetry between the switches to maintain signal quadrature. The Allegro patented, high-frequency chopper-stabilization technique cancels offsets in each channel providing stable operation over the full specified temperature and voltage ranges.

Additionally, the high-frequency chopping circuits allow an increased analog signal-to-noise ratio at the input of the digital comparators internal to the IC. As a result, the A1230 achieves industry-leading digital output jitter performance that is critical in high performance motor commutation applications. An on-chip low dropout (LDO) regulator allows the use of this device over a wide operating voltage range. Post-assembly factory programming at Allegro provides sensitive switch points that are symmetrical between the two switches.

Bipolar Switch Applications and Working from Allegro Micro
There are four general categories of Hall-effect IC devices that provide a digital output: unipolar switches, bipolar switches, omnipolar switches, and latches. Bipolar switches are described in this application note. Similar application notes on unipolar switches, omnipolar switches, and latches are provided on the Allegro™ website.

Bipolar sensor ICs are designed to be sensitive switches. (Note that the term “bipolar” refers to magnetic polarities, and is not related to bipolar semiconductor chip structures.) A bipolar switch has consistent hysteresis, but individual units have switchpoints that occur in either relatively more positive or more negative ranges. These devices find application where closely-spaced, alternating north and south poles are used, resulting in minimal required magnetic signal amplitude, ΔB, because the alternation of magnetic field polarity ensures switching, and the consistent hysteresis ensures periodicity.


Applications for detecting the position of a rotating shaft, such as in a brushless dc motor (BLDC) are shown in figure 1. The multiple magnets are incorporated into a simple structure referred to as a “ring magnet,” which incorporates alternating zones of opposing magnetic polarity. The IC package adjacent to each ring magnet is the Hall bipolar switch device. When the shaft rotates, the magnetic zones are moved past the Hall device. The device is subjected to the nearest magnetic field and is turned-on when a south field is opposite, and turned-off when a north field is opposite. Note that the branded face of the device is toward the ring magnet.



1 2 3