The Lie Detector Circuit

Here is the figure that shows to us about design circuit of the lie detector circuit;

In this circuit, it has the two probes shown are held in the hands and the skin resistance applies bias to the transistor. The 5 k ohm pot is set for zero deflection on the meter. When the "subject" is embarrassed or lies, sweating on the hands takes place, increasing the bias to the transistor and upsetting the bridge balance.[Circuit diagram source: Seekic.Com]

Home Made Geophone Detects Foot Stomp Circuit

This is a design circuit for geophone detector circuit that can be use in home. Here’s the figure of the circuit;

This circuit is made from a strong magnet, a coil of wire and a rubber band. The circuit is sensitive enough to detect the vibrations of a nearby foot stomp.  It could be used as an earthquake detector.

Edge Sensor Circuit

When the robot will be running on a black surface with a white edge. It has to stay on the surface and not wonder off the platform on its own. Thus, it must be able to detect the white edge of the platform. This circuit is use to detection the platform of the edge. Here’s is the simple circuit diagram schematic;

Infrared Tx/Rx pair is ideal for this application because the distance between the sensors and surface will be very small if the Tx/Rx pairs were mounted under the robot. An advantage of this location is that they will not be affected by ambient lighting conditions. It is preferred that Tx/Rx pairs are used for optimum performance because the peak sensitivity wavelength of the detector are that of the emitter's.

Economy Radar Detector Circuit

This is a design circuit for build the economy radar detector circuit. This circuit uses a 1458 dual op-amp to form a radar detector. Here’s the figure of the circuit;

C1 is the detector of the radar signal. The first op-amp forms a current-to-voltage converter and the second op-amp buffers the output to drive the piezo transducer. R5 sets the switching threshold of the second op-amp; normally it is adjusted so that the circuit barely triggers on background noise, then it's backed off a bit. The response of the circuit may be tuned by adjusting the length of the leads on C1. For typical road-radar systems, the input capacitor's leads should be about 0.5 to 0.6 inches long. [Circuit diagram source: electronics-lab.com]

Dual Liquid Level Sensor Circuit

This is a design circuit for dual liquid level detector. Here’s the figure of the circuit;

This circuit is use CA3410 quad BiMOS op amp to sense small currents. Because the op amp's input current is low, a current of only 1 μA passing through the sensor will change the converter's output by as much as 10 to 12 V. [Circuit diagram source: seekic.com]

Dual Detector Prevent Locking On Sidebands

Here’s the figure of the design circuit for dual detector to prevent locking on the sideband circuit.

Anti sideband circuit rejects side-band locking while telemetry tracking loop is automatically searching for signals around i-f value. Circuit also provides both p-m and aim demodulation. Emitter-follower Q1, receiving i-f signal, feeds discriminator Q6-07 through limiters Q2-Q3 and Q4-05. For 455-kc input, d-c outputs of diode detectors cancel at hose of Q8. For lower or higher frequencies, difference voltage serves to apply anti sideband error signal to loop fiber through Q9 or Q10. [Circuit diagram source: Seekic.com]

Crystal FM Detector Circuit

This is a design circuit for crystal FM detector circuit. Here’s the figure of the circuit;

Exar XR-215 PLL IC is operated as crystal-controlled phase-locked loop by using crystal in place of conventional timing capacitor. Crystal should be operated in-fundamental mode Typical pull-in rangeis±1kHz at l0 MHz. [Circuit diagram source: Seekic.com]

Contact Sensor Circuit for Robots

This is a simple design circuit for contact detector circuit. Here’s the figure of the circuit;

The robot's obstacle detection circuit will only inform the robot that there is an obstacle, not the distance between the obstacle and the robot. Therefore contact sensors are needed for the robot to determine that it has made contact or dumped into an object. This circuit above is a simplest solution that can be use for micro switches. There are four micro switches (one on each side of the robot), connected to The Handy board's digital ports.

Bat Detector Circuit

This circuit is a simple design circuit for bat detector circuit that is a frequency division type device. Frequency division type detectors allow you to hear ultrasonic sound by digitally scaling the frequency down into the human hearing range. Here’s the figure of the circuit;

Basically this circuit is essentially composed of 3 integrated circuits, or ICs. The signal from an ultrasonic transducer is fed to IC-1, an LM386 audio amplifier, which is configured to provide a signal gain of 200. The signal is coupled to IC-2, a second LM386, by a .05 uf capacitor. IC-2 is configured to provide an additional gain of 20, for a total system gain of 4,000. The output of IC-2 is direct coupled to the input of IC-3, a 7 stage CMOS digital divider circuit. 

The input stage of the divider acts as a zero crossing detector, triggering on the negative transition of the signal from IC-2. The divide by 16 outputs connected to a potentiometer, which serves as an audio level control. A high impedance ceramic earphone is connected to the output of the level control. The 10K level control is a small printed circuit pot that is set and forgotten. The detector circuit is powered by a nine volt battery. (The numbers next to the IC nodes refer to the pin numbers of the IC's. Note the additional pins listed at the bottom of the schematic that need to be tied to ground).

Two-Wire Temperature Sensor Using LM35 IC

This is a design circuit for temperature sensor circuit. This is the figure of the circuit;

The function of LM35 temperature sensor is a produces an output voltage that is directly proportional to the measured temperature in degrees Celsius, and it enables temperatures below zero to be measured. This Circuit is a temperature-dependent current source, since it uses the variation of the quiescent current with changes in temperature. Component: LM35 IC, Resistor, Capacitor. [extremecircuits.net]

QTR-1A Reflectance Sensor Circuit

This is a design circuit of reflectance sensing circuit. Here’s the figure of the circuit;

Function: For reflectance sensor. Component: VCC, Ground, Resistor, Cable, Board, LED, Digital I/O.

LM741 Light Dark Sensor Circuit

This is a design for dark light sensing circuit. Here’s the figure of the schematic circuit;

Function: extremely useful and versatile in a wide range of renewable energy projects from automatic lighting to security systems. Component: Transistor, Potentiometer, Capacitor, Relay, LDR, LED Spotlight.

LM336 Temperature Measurement Circuit

This is a design circuit that used for Fahrenheit measurements. Here’s the figure of the circuit;

In this case the freezing point is adjusted at 320F. At 2120F, P2 is adjusted to obtain 0.9V at output. Component: LM336 IC, Thermistor, Resistor. [electroschematics.com]

LM134-LM10 Thermometer/Temperature Sensor Circuit

This is a design circuit of the thermometer/temperature sensor circuit. This circuit is using LM10 or LM134. This is the figure of the circuit;

The ideal meter for this circuit is a 0-200uA digital ampere meter, which can show both positive and negative polarity. This will make the circuit suitable for indicating temperatures below 0°C.

Fully Linear Diode Sensor Circuit Based On The A748 IC

This circuit is design for full linear diode sensing circuit. Here’s the figure of the schematic circuit; 

This circuit based on the A748 IC. Features: op amp as constant-current source, 1 V at  50 degrees Celcius. Diode or Transistor Makes Fully Linear Thermometer. Component: A748 IC, Resistor, Capacitor, Diode.

Drinking Water Alarm Sensor Using LM555

This is a design circuit for fabricating this water sensor, you need two foils an aluminum foil and a plastic foil. You can assemble the sensor by rolling aluminum and plastic foils in the shape of a concentric cylinder. Here’s the figure of the circuit;

In this situation, this water alarm circuit will save the people from long wait as it will inform them as soon as the water supply starts. At the heart of this circuit is a small water sensor.  Component: LM555 IC, Resistor, Switch Capacitor, Speaker. [extremecircuit.com]

Devantech SRF04 UltraSonic Sensor Circuit

This is a design circuit for about Devantech SRF04 UltraSonic Sensor To The SV203 powered PPRK Circuit Diagram. Here’s the figure of the circuit;

This circuit based on the Devantech SRF04 sensor. Features: minimum of 10m sec to initiate the sonic pulse (the trigger), fairly simple, held low (logic 0) input line. Component: Capacitor, Resistor, Junk, IC, Battery, Infrared, Transistor.

Anti-Theft Security For Car Audios CD4093 IC

This is a design circuit for security. This is the figure of the circuit;

This circuit can be effectively used for protecting your expensive car audio system against theft. And it based on popular CMOS NAND chip CD4093. Component: CD4093 IC, Resistor, Transitor, Capacitor, Diode.

AD590 IC For Celsius To Digital Thermometer Circuit

This is a design of Celsius To Digital Thermometer Circuit Diagram. Here’s the figure of the circuit;

This circuit based on the AD8541 IC. Features: designed by Elana Lian and Chau Tran from Analog Device, low-cost AD590 temperature sensor; trimming potentiometer; and an ADC, proportional outputs current. Component: IC, Resistor. [diagramwiring.net]

7BL05 IC For Digital Electronic Thermometer Circuit

This is a circuit for digital electronic thermometer circuit diagram. Here’s the figure of the circuit;

Features: 1N4148 diode as the temperature sensor, -2 mV / 0C temperature coefficient, digital multi meter for measure temperature values from -9.990C up to +99.90C, digital voltmeter, diode senses. Component: 7BL05 IC, Capacitor, Resistor, Diode. [electroschematics.com]

Resistance Sensor Circuit

Electrical resistance is the easiest electrical property to measure precisely over a wide range at moderate cost. This is a simple design application for digital multimeter costing a few tens of dollars can measure resistances in the range 10 ohm to 10 megohm with a precision of about 1% using a two-wire technique. 

Providing RL1 and RL2 are well-matched, three-wire techniques can be used. Circuit 2 employs two matched current sources, I1 and I2, to eliminate the effects of lead resistance. Circuit 3 is an AC-bridge that is in-balance when RX=RY. If a lock-in amplifier is used as a null-detector, determination of RX with an extremely low excitation current is possible.

TL071 JFET Light Sensor Circuit

This is a design circuit for light sensing circuit. Here is the schematic figure circuit;

Above picture shows how to use an ordinary LED as a light sensor. It makes use of the photovoltaic voltage developed across the LED when it is exposed to light. Component: TL071 IC, Resistor, Diode.

Robotics IR Navigation Sensor Circuit

This is a design circuit about Robotics IR Navigation Sensor Circuit Diagram. This is the figure of the circuit;

Features: one chip 74HC04, IR sensor will work in direct sun light, Sharp GP1U581Y, very good range. Component: IC, Resistor, Capacitor, Diode, Transistor.

Photo Sensor Circuit For Street Light

This is a design circuit for Photo Sensor Circuit Diagram For Street Light Electronic. This circuit using the 2N3906 Transistor. Here is the figure of the circuit diagram;

Features: lower value for the 7.5K resistor, common emitter resistor for positive feedback, be adjusted to about half the supply, 8 volts and 4 volts switching points. Component: Transistor, Resistor, Diode, Relay.

Inductive Displacement Sensor Circuit

The voltage at the output of circuit 7 depends on the position of the high-permeability core (in blue) which is changed with a mechanical linkage (in red). The output signal must be monitored with a phase-sensitive detector. Here is the figure of the inductive displacement sensor circuit;

There is a null position at the midway point between the two detection coils, which are connected in series-opposition. Commercial devices can have linear ranges from less than 1 mm to more than 250 mm with resolutions of 1 part in 100,000 within the linear range. Inductive displacement transducers can be purchased with integral electronics that internally generates the alternating current and converts the measured signal into a calibrated DC output.

Heat Sensor Circuit Based On LM741

This is a design circuit of the Heat Sensor Circuit Diagram. This circuit based on the LM741 IC. This is the figure of the circuit;

 

Features: temperature is almost simple sensor data subsequently amplified by Op-Amp 741, NTC thermistor as a sensor, automatically fan, thermal sensor. Component: IC, Resistor, Transistor, Relay, Diode, Transformer.

Dew Detector Probe Circuit

This is a circuit for Dew Detector Probe circuit works on 5V dc supply. It is useful for checking the presence of dew (condensed moisture) inside sensitive electronic devices like VTR, camera, copier, computer etc. This is the figure of the circuit;

The principle of the ready made dew sensor element is based on the change in resistance of a conductive polymer in a thin film on a small ceramic substrate. As the sensing polymer wet (90 to 95% Relative Humidity), its resistance will increase drastically because the polymer expands and therefore causes a larger distance between the conductive particles. After successful construction, enclose the whole unit in a small aluminum tube.

Capacitive Pressure Sensors Circuit

This is a design circuit for capacitive pressure sensors use a thin diaphragm, usually metal or metal-coated quartz, as one plate of a capacitor. The diaphragm is exposed to the process pressure on one side and to a reference pressure on the other. Here is the figure of the schematic circuit;

 

Changes in pressure cause it to deflect and change the capacitance. The change may or may not be linear with pressure and is typically a few percent of the total capacitance. The capacitance can be monitored by using it to control the frequency of an oscillator or to vary the coupling of an AC signal. It is good practice to keep the signal-conditioning electronics close to the sensor in order to mitigate the adverse effects of stray capacitance.

Bosch LSU 4 Sensor and WEGO Circuit

That is a design circuit that shows about Bosch LSU 4 Sensor and WEGO Circuit Diagram. Here’s the figure of the circuit;

Features: included built-in data logging, used the new Bosch LSU 4.2 wide-band sensor, substantially less than the price of the original unit, much lower cost. Component: Power Supply, Resistor, Transistor.

12V PIR Sensor Timer Circuit

This is a circuit that shows about 12V PIR Sensor Timer Circuit Diagram. Here’s the figure of the schematic of the circuit;

Features: 12 Volt DC, will turn on a floodlight or other device for a time in seconds,  suited to many standalone motion detecting designs, alternative type of PIR sensor module, PIR Relay Timers. Component: Transistor, Capacitor, Resistor, Diode, Relay, Switch.