Test and Measurement Circuits

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Metal Detector Circuit

This is a project of a simple metal detector circuit. The circuit is easy to build using only one transistor and few other components. The circuit is a colpitts oscillator....

555 Tester Circuit

Here is a project of a 555 tester circuit which is very useful to check 555 timer ICs. In this circuit the NE555 IC is wired as an astable multivibrator....

Water Level Indicator

This is a simple water level indicator circuit or water level sensor circuit. The circuit is very easy to build and contains only three PNP transistors and....

Infrared Detector Circuit

Simple infrared detector circuit which can be used to detect infrared light. The circuit is consist of only three components a RS-276-145 photo transistor, 330 Ohms....

Remote Tester Circuit

A remote tester circuit or remote checker circuit which can be used to test TV and other remote controls. The circuit is very simple using only few components....

Triac OR SCR Tester Circuit

Triac or SCR is a very useful component, although it is not used in all electronic devices or circuits but in some electronic circuits it perform very essential tasks...

Plant Soil Moisture Tester Circuit

A very simple and useful project of soil moisture circuit. The circuit is using only four components and a 3 volt battery. The circuit will detect...

IR Detector Circuit

Here is a IR detector circuit which will detect IR from any equipment which emits IR and lights up an LED which will show the indication of IR beam...

Continuity Tester Circuit

A simple DIY LED continuity tester circuit which can be built in few minutes using only two companents a 390 Ohms resistor and LED. This continuity...

Crystal Tester Circuit

A very useful project of a crystal tester circuit or xtal tester circuit built with only few components the circuit form an oscillator that will only oscillate if...

Transistor Tester Circuit

This is a very simple transistor tester circuit the circuit can be used to test NPN and PNP transistors. The voltage source is a 6V power supply...

3-Digit DVM Voltmeter

Circuit of a three digit voltmeter using 3161, CA3162 ICs

Simple Capacitance Meter

A useful circuit diagram of simple capacitance meter it will measure capacitors from 1pF to 22uF range.

555 Timer Circuit

The circuit mentioned here is a ten minutes timer, after pusing the button S1 the LED2 will become light after 10 minutes.

Moisture Sensor Alarm

The project mention here is a versatile moisture sensor alarm circuit. The circuit is quite sensitive and can be used to detect moisture in many things for example...

Simple Water Level Sensor Or Liquid Level Detector

A water level sensor or liquid level detector is a very useful device for measuring or detecting a required level of water, liquid, fluid in a tank, pool, well, aquarium, washing machines etc...

Plant Watering Watcher Or Dry Soil Detector

The schematic shown here is a circuit of plant watering watcher or dry soil detector. The plants located in your home or office wants more care as compare to...

Simple Water Level Buzzer Circuit

Here is a simple water level buzzer circuit which can be used to detect or sense the level of water. The circuit can be built in few minutes if all parts are available with you.

Water Level Alarm Circuit

Here is the schematic of a water level alarm circuit. The circuit will work as a water level sensor and will give a melodious alarm sound when the two probes...

Rain Sensor Alarm

A rain sensor alarm circuit can be a very beneficial device for alerting when rainfall happens. The rain detector circuit shown here is very simple using...

Rain Detector Switch Using Relay

Here is a circuit of a rain detector switch using relay which can be used to switch off your electronic appliances outside the home when rainfall starts...

Wireless Water Level Indicator

This circuit can be used for many different water level indicator tasks for example you can use it as a water level alarm for water tanks, pools, washing machines...

Water Or Liquid level Sensor Relay Switch

Here is a schematic of a simple water or liquid level sensor relay switch circuit, which can be used to switch on or off electronic appliances at the desired level of water...

Simple Touch Switch Circuit

Here is a project of a simple touch switch circuit. This circuit and can also be used to activate a relay in the place of LED and resistor. The circuit is quite sensitive...

Simple Water Level Indicator Circuit

Project of a simple water level indicator circuit. The circuit is very easy to build and can be made in few minutes if you have an LED, a 470 Ohms resistor and...

Temperature Sensor Circuit

The schematic shown here is a project of a simple temperature sensor circuit or we can also say it a heat sensor circuit, which will activate an LED when receive heat...

Temperature Sensor Relay Switch Circuit

The circuit presented here is a project of a temperature sensor relay switch circuit which will switch on the relay and any device connected to the relay when the...

Temperature Alarm Circuit

The schematic shown here is a project of a simple temperature alarm circuit. The circuit will activate the buzzer alarm when it will detect or sense heat...

Temperature Control Circuit Using 555 IC

The figure shows a very useful project of a temperature control circuit using 555 IC. The circuit can be used to control any AC or DC device on the desired temperature...

Water Level Alarm Using 555 IC

The circuit presented here is a project of a water level alarm circuit using 555 IC. The circuit will produce an alarm sound when the level of water will reached...

Moisture Level LED Meter

Here is a very simple and useful project of a moisture level LED Meter circuit that can be used as a sensor or detector to measure humidity or moisture level in plants, soil...

Crystal Test Circuits

Two simple crystal test circuits.

Heat / Temperature Sensor Alarm

Here is a simple and easy to make heat or temperature sensor alarm circuit. A good feature of this circuit is that it will...

Temperature Sensor LED Meter

Here is a very easy and useful schematic of a temperature sensor LED meter circuit. The circuit can be used to sense high and low temperature levels and shows visual...

Heat Sensor With LM741

The figure below shows a very useful and efficient project of a heat sensor circuit with LM741 IC. The circuit will activate a relay switch on the preset level of temperature or heat.

DC Motor Control PWM With 555

This simple DC motor control or PWM circuit using 555 IC can be used to control the speed of a DC motor. The circuit is very simple and can be built...

Wireless Temperature Sensor

The wireless temperature sensor circuit shown here is an ideal circuit to use to detect a level of temperature or heat from distant place...

Temperature Sensor Using Diode

The figure below shows a project / schematic of a simple and low cost temperature sensor using a 1N4007 diode...

Cold Sensor Switch

The figure below shows a project of a very sensitive cold sensor switch circuit that can be used to sense coldness or low temperature...

Digital Thermometer

Here is an easy & accurate digital thermometer circuit that can be used for variety of purposes like monitoring indoor or outdoor temperature...

Moisture Sensor Switch

This simple moisture sensor switch circuit can be used to switch ON any equipment on the certain level of moisture content in any substance like soil, wood etc...

Sensitive Moisture Sensor

simple moisture sensor switch circuit can be used to switch ON any equipment on the certain level of moisture content in any substance like soil, wood etc...

Automatic Plant Watering / Irrigation Control

The figure below shows a schematic of a simple automatic irrigation system control circuit for automatically watering your plants in lawn, garden, farm etc...

Temperature Controlled Fan

A temperature controlled fan circuit can be a very useful device to ON and OFF a DC 12V fan according to the changes in temperature...

Simple Temperature Controlled DC Fan

Simple temperature controlled DC fan circuit using a single transistor and few other components...

Automatic Rain Sensing Windshield Wiper Control

The figure below shows a project / schematic of an automatic rain sensing windshield wiper control circuit using 555 timer IC...

Static Electricity Detector

A very interesting and simple project of a highly sensitive static electricity detector circuit, it can also be used as ion detector, electric field detector etc.

Non Contact AC Voltage Detector

This is a very easy useful project of a non contact AC voltage detector circuit. The circuit will blink an LED and make beep beep sound when it detects any AC field...

555 Rain Detector / Sensor Alarm

Here is a very interesting project of a 555 rain detector / sensor alarm circuit. The circuit will produce a melody when the sensor will detect any water drops...

VU Meter

The figure shows a schematic diagram of a VU meter circuit. A VU (Volume Unit) meter is a very useful device to show the audio level in audio devices...

IR Remote Tester With Alarm

This is a project of an IR remote tester circuit with alarm. It can be used to test the output of any IR remote like TV, DVD player, audio player etc...

Automatic Water Pump Controller

Here is a very useful project of an automatic water pump controller circuit. The circuit will automatically switch ON and OFF any water pump on the required level of water...

Sensitive Static Electricity Detector Switch

The figure shows a very sensitive static electricity detector switch circuit. The circuit will activate an LED and a relay switch when it will detect any static electricity...

Hourly Chime & Switch Using 555

This is a project of an adjustable hourly chime & switch circuit using 555 IC or we can also say it 555 alarm clock...

Super Sensitive Vibration Sensor

Here is a very interesting and useful project of a super sensitive vibration sensor switch circuit. The circuit can be used for variety of applications for example as a door...

Electric Field Detector

This electric field detector circuit is a very useful project to detect electric fields around AC wire, socket etc...

555 One Shot Timer

This is a 555 one shot timer circuit. The circuit will not repeat it's timing cycle if the push switch S1 will remain ON or pressed, after a timing cycle is completed...

Knock Sensor Circuit

This is a project of a knock sensor circuit, it is a very interesting circuit and can be used to detect the door or table knocking and switch on a relay for a preset time...

Temperature Controlled Fan Using 555

The figure below shows a circuit of an automatic temperature controlled fan using 555. The circuit will control the speed of the fan automatically according to...

Electronic Number Guessing Game

Here is a project of an electronic number guessing game circuit. There are 10 LEDs used in the circuit on which you have to mark 1 to 10 numbers, you have to choose...

555 Pulse Generator

This is a project of a 555 pulse generator circuit. The circuit can be used with any project, which require positive pulses. An LED is used at the output of the IC to show...

Static Electricity Detector Using CA3140 IC

This is a project of a simple static electricity detector using CA3140 IC. The circuit is very sensitive and can detect static charge from distance of one or two meters...

Simple Burglar Alarm

The figures below showing two projects of simple burglar alarm circuits using single transistor. There are many types of burglar alarms are available to build using...

Wire Break Or Burglar Alarm Using 555

Project of a simple wire break or burglar alarm using 555 IC. The circuit is very simple and using not more three parts which are a 555 timer IC, a 100K resistor...

Door Security Alarm

Here is a very useful project of a door security alarm circuit. The circuit can be used for security purposes for example it can be used at the door and...

Loud Door Security Burglar Alarm

This loud door security burglar alarm circuit can be used to secure the doors to detect intrusion or any unauthorized entry...

Fridge Door Alarm

The figure below shows a very useful project of fridge door alarm circuit.The circuit will provide an audible alarm if the door of the fridge is left open for a long time period...

Automatic Plant Irrigator With 555 IC

This is a project of an automatic plant irrigator circuit with 555 IC. The circuit is able to water your plants automatically when you are away from home...

Sudden High Voltage Detector Alarm

This simple high voltage alarm circuit will indicate when the mains voltage rises suddenly. The circuit will produce an audible alarm when it detects high voltage...

Missing Pulse Detector Using 555 Timer IC

This simple high voltage alarm circuit will indicate when the mains voltage rises suddenly. The circuit will produce an audible alarm when it detects high voltage...

Smoke Detector

This is a project of a smoke detector circuit. The circuit can detect the smoke produced in the result of burning of anything...

Simple Metal Detector

Here is a simple metal detector circuit using a CA3140 IC. There are many metal detector circuits or kits are available to built but mostly are very...

LM741 Timer

The figure below shows two very simple projects of 741 timer circuits. The heart of the circuit is a LM741 IC. LM741 is a very famous op amp IC built to...

Timer With Alarm

Here is the project of a simple timer with alarm circuit using a CD4060 IC. The circuit can be adjusted to provide timing cycle of 1 minute to many hours...

Triangle Wave Generator Using 555 IC

The figure below shows a simple triangle waveform generator circuit using a 555 IC. This is a very simple and low cost technique to make a triangular wave generator...

Door Open Indicator For Multiple Doors

This simple multiple door open indicator circuit can be used to detect or monitor if any door has left opened. The circuit can be used for variety of purposes for example...

Movement Sensor

This is a very interesting project of a movement sensor or detector circuit. The circuit is using a pendulum and can detect movement of any object and can be used for...

Simple One Transistor Code Lock

Here is a very simple and interesting project of simple one transistor code lock circuit. This circuit is using only few components, which are one transistor, two resistors...

Movement Sensor Alarm Using 555 IC

This article describes a very interesting project of the simple movement sensor or detector alarm circuit using a 555 IC. The circuit can detect movement...

Wireless Movement Monitor

Here is another great project of a wireless movement sensor or monitor circuit. The circuit can monitor your large objects and inform you wirelessly at a distance of...

Wire Loop Game

This is a project of a wire loop game circuit. A wire loop game is a very famous game, it consist on a wire loop and a shaped wire. The method to play this game is to...

Automatic Municipal Water Supply Sensor Switch

Here is a project of an automatic municipal water supply sensor switch circuit. The circuit will sense when the water will come in the municipal water supply line...

Simple Motion Sensor Alarm & Light

This simple motion sensor alarm and light circuit is using a passive infrared sensor module also call PIR sensor module. The circuit will detect movement of any human, animal or an object...

Automatic Door Sensor Light

Here is a very useful project of an automatic door sensor light circuit. The circuit will automatically activate light of a room, storeroom, washroom etc...

Hall Effect Sensor Switch

This is a project of a hall effect sensor switch circuit. The circuit is very simple and using just four components that are a US1881 hall effect sensor switch,...

Simple Magnetic Field Detector

The figure below shows a project of simple magnetic field detector or sensor circuit that can detect a magnetic field around. The circuit is very useful and can be used...

Simple Stop Watch Project Using 555 IC

The figure is showing a simple stop watch project. The circuit is easy to build and using very few parts which are a 555 timer IC, a calculator and few other components...

Simple Magnetic Pulse Counter Using Hall Sensor

This simple circuit of magnetic pulse counter using hall effect sensor can be used for purposes like for counting the speed of motor or counting any type of magnet...

Object Counter

The figure below shows a very simple and useful project of an object counter circuit. The circuit is using a laser light, a cheap 8-digit calculator and few other components...

Water Level Controller With Buzzer

The article describes a very useful project of a water level controller circuit with buzzer. The circuit is completely automatic and can control a water pump it self...

Water Boil Alarm

The circuit will indicate when your boiling water will reached on the boiling point by activating an audible alarm and activating an LED...

Temperature Controlled Switch Using LM35 & CA3140

Here is the project of a temperature controlled switch using LM35 and CA3140 ICs. The circuit can be used for variety of temperature sensing purposes...

Dual Time Delay Relays Using 556 IC

This dual time delay relays circuit is using a 556 timer IC. The circuit is operating two relay switches, both can be adjusted for different time periods...

Cold Sensor Using 555 IC

A good cold sensor alarm or switch can also be made using a 555 timer IC, The circuit is using a thermistor and very few discrete components. The circuit is very simple...

556 Dual Timer Tester

A 556 dual timer tester circuit is also an important circuit to have in your electronics lab if you are making projects with 556 dual timer IC...

Plant Soil Moisture Sensor Alarm Using 556 IC

The circuit shown here will provide beep beep sound from the buzzer and flashes an LED when there is not much water content in the plant soil...

Adjustable Timing Pulses Generator

The circuit shown here will provide beep beep sound from the buzzer and flashes an LED when there is not much water content in the plant soil...

Ultra Sensitive Vibration Sensor

Here is a project of an ultra sensitive vibration sensor using CA3140 and a 555 timer IC. The circuit can be used for variety of purposes for example vibration sensor...

Knock Sensing Code Lock

This is a project of an automatic knock sensing code lock circuit. The circuit requires two different codes to switch on the relay at the output...

Smart Combination Lock

Here is a project of a very smart and efficient electronic combination code lock circuit using few NE555 Timers and 4017 CMOS decade counter ICs...

Electronic Coin Toss With Slow Down Function

An electronic coin toss is a very interesting and useful project in electronics. The circuit shown here is using a slow down function in which the LEDs...

Simple Moisture Sensor Using 555 IC

This is a project of a simple moisture sensor using 555 IC. The circuit will activated an LED, a peizo buzzer and a relay switch when the moisture level reach to the...

Continuity Tester With Buzzer

If you are working with your electronic projects or repairing any electronic circuit a continuity tester is an important device to have on your bench. A continuity...

Continuity Tester Using 555 Timer IC

The figure below shows a very useful project of a continuity tester using 555 timer IC. It can be used to check faulted wires and circuits...

Non Contact AC Voltage Sensor Using LM358

Here is a very useful project of a non contact AC voltage sensor circuit. The circuit can be used to sense AC voltages in AC sockets, AC wires without making any contact...

Contactless AC Mains Detector Relay Switch

This contactless mains detector relay switch circuit will activate a relay switch when an AC voltage is presents in main lines and deactivates it when AC voltage is not...

Heat Sensor Switch Using LM393N Voltage Comparator IC

This article describes a project of a simple heat sensor switch using LM393N IC. LM393N is a dual voltage comparator IC with many...

Simple Sensitive Knock Sensor

Here is a project of a simple and sensitive knock sensor circuit. The circuit will blink LEDs when it will detect any knock or vibration on the surface where it is placed...

Super Sensitive Vibration Sensor (Improved Version)

This is an improved version of super sensitive vibration sensor. This version is more sensitive than the previous circuit and also power saver...

Touch & Knock Sensitive Smart Soldering Iron

The figure below shows a very useful project of a touch & knock sensitive smart soldering iron timer. The circuit will automatically switch on soldering iron for a preset...

Automatic Water Pump Controller (Transistor Based)

This is a low cost project of an automatic water pump controller using some transistors, a relay, a BT139 triac, transformer and few other discrete components...

Contact Less Mains Power Failure Alarm

Here is a very useful project of a contact less mains failure alarm circuit. The circuit wirelessly detects the absence of AC mains voltage in the lines and alarms...

Simple Headlight Reminder

The circuit will make a melodious alarm to remind if the vehical headlights is left open after closing the ignition switch...

Contact Less Car Door Left Open Reminder Alarm

This simple contact less car door left open reminder alarm will give beep beep buzzer when any door of your car is not closed properly. The circuit is simple and using few...

Car Reverse Horn

This is a project of a simple car reverse horn circuit. The circuit will generate a musical horn when the car is in reverse gear. The circuit is very simple to build and also...

Car Reverse Alert Buzzer & Flasher

The figure shows a very useful project of a car reverse alert buzzer and flasher circuit. The circuit can be used with any vehicle for example cars, jeeps, trucks etc...

Contact Less Car Reverse Or Backup Alarm

Here is a very interesting project of a simple contact less car reverse or backup alarm circuit. It cannot only use with car but you can use it with any vehicle...

Mains Power Come Back Alarm

The circuit shown here will alert you every time the mains power come back by indicating you through a melody alarm...

Daytime Car Headlights Switch ON Reminder

We often require to open the car headlights in day time but some times we forget to switch them off because we cant realize that either they are open or closed due to...

Heat Sensor Using LM358 IC

This is a simple circuit of a heat sensor using lm358 IC. The circuit can be adjusted to activate a relay switch on a desired level of heat. Any AC or DC appliance could be...

IR Sensor Using LM324 IC

The figure below shows a project of a simple IR sensor circuit using LM324 IC. The circuit will show visual indication by activated an LED when any object is placed...

Temperature sensing switch using LM35 & LM358

Here is a good quality temperature sensing switch using LM35 & LM358 IC. The project can be used to control variety of electronic devices on a desired temperature...

Four Level Temperature Sensor Using LM324

This article describes a very good quality four level temperature sensor using a LM324 IC. The circuit will show visual indication by activating LEDs on four different preset...

Two Level Temperature Sensor Using LM358

This is a project of a simple two level temperature sensor using LM358 IC. The circuit can be easily calibrated to two different temperature levels...

Two Level Temperature Switch

The figure shows a two level temperature switch circuit. The circuit can be adjusted for two different temperature levels There are two relay switches used at the output...

Four Level Temperature Controlled Switches

Here is a project of a four level temperature controlled switches. At the output of the circuit there are four relays, each relay will be adjusted to activate on the desired...

Six Level Wireless Water Level Indicator

This Six level wireless water level indicator can wirelessly indicate the level of water. The project contains two circuits, one is a water level sensor cum transmitter...

light Intensity Measurement Meter Using LM324

We cannot detect the minor differences or changes in the intensity of light due to which we have to use a LUX meter for light intensity measurements...

Simple Water Level Indicator Using ULN2803

This is a project of a simple water level indicator using ULN2803 IC. The circuit will indicate 8 levels of water. At the output of the circuit there are 8 LEDs, which will...

Water Level Indicator With Pump Controller

Here is a very interesting and useful project of a water level indicator with pump controller. The has 8 water level sensing points and it will automatically switch on...

Solar Water Pump Controller

The figure below shows a project of a solar water pump controller circuit. The circuit will automatically switch ON water pump when water level in the tank reached below...

Water Level Indicator With Alarm

This water level indicator circuit can sense seven levels of water and shows visual indication by LEDs. The circuit also alarms when the water reaches to the top level...

Simplest Automatic Water Pump Controller

This is a simplest circuit of an automatic water pump controller. The circuit will automatically switch ON a water pump when the water level is below from the...

Wireless Water Pump Controller (Laser Based)

Here is a project of an automatic wireless water pump controller circuit based on laser. The circuit is fully automatic and once it is setup, it will serve for years...

Cold Sensor Switch Using LM35 & CA3140

This is a project of a cold sensor switch circuit using LM35 IC andCA3140 ICs. The circuit can be used for sensing cold at any place or environment...

Multipurpose Vibration Sensing Alarm

This multipurpose vibration sensing alarm can be used for many purposes for indoor and outdoor. In indoor it can be used on doors and windows to alert you...

Simple Electromagnetic Radiation Detector

The figure below shows a project of a simple electromagnetic radiation detector or sensor circuit. It can detect electromagnetic filed generated from different electronic...

Multidirectional Seismic Sensor

Here is a project of a multidirectional seismic sensor circuit. The circuit is very sensitive and can detect seismic waves generated by any mean...

Simple Time Delay Switch Using CD4011

CD4011 is a versatile IC and can be used for variety of different purposes. It is actually a CMOS IC built with NAND logic gate technology. The IC can be used to build...

Simple Remote Tester

This simple remote tester circuit can be used to test any remote control used for electrical appliances for example TV, DVD etc...

Simple Automatic Water Pump Controller

The article describes a simple low cost automatic water pump controller circuit. The circuit measures water levels in the tank with the three probes,...

Home & Office Basement Flood Alarm

This home and office basement flood alarm will indicate you when flood start's to enter in your places. The circuit provides early indication and alert...

Motion Sensing Melody Alarm

This motion sensing melody alarm circuit can be used for variety of security and indication purposes. For example it can be used to detect the entry of...

Power Outage Time Estimator

This simple power outage time estimator will automatically starts calculating the time of power outage in your absence and shows on the screen of the calculator...

Simple Motion Sensor Doorbell

With this simple motion sensor circuit you can change your home doorbell into completely automatic doorbell that will activate automatically when a visitor come...

Motion Sensing Main Gate Night Light

Here is a very interesting and useful project of a motion sensing main entrance gate night light circuit. The circuit will automatically switch ON the Lamps / lights...

Loud Security Alarm Using PIR Sensor Module

There are many techniques to make a security alarm for example it can be made by using laser systems, infrared systems, touch sensors, vibration sensors etc...

Digital Variable Resistor

The figure shows a useful project of digital variable resistor circuit, the circuit is very versatile and can be replaced with any analog variable resistor...

Servo Motor Controller Using 555 IC

A servo controller circuit can be built with several techniques. The figure below shows a very simple servo controller circuit using a 555 timer IC. A servomotor is a very...

LED Thermometer With Selectable Temperature Switch

This article describes a project of LED thermometer with selectable temperature switch. The circuit can be adjusted for any temperature range; a relay switch...

Door Left Open Indicator Alarm

This simple project can be used to make a door security system. It will alert if the door is left open and it is not closed after a set time period in the circuit...

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