Relay driver circuit using ic uln2003 with applications. Here, i am using uln2003a to control relay and from this relay we can control anything. It is a revised version of my previous picbased relay timer project with added features and some improvements in the circuit design part. Like my previous version, it also allows you to set both on and off times. Some of the other applications of uln2003 include logic buffers, lamp drivers, line drivers, led display, motor driver circuits etc.
You can find the coil pins by using an ohmmeter and looking for the two pins that have about 50150 ohms between them, those are your coil. Here is a simple solution that uses fewer parts to conserve significant energy. Uln2803 is used as a driver for port io lines, drivers output connected to relay modules. How to drive a relay using microcontrollers this entry was posted on march 2, 2014. Relay is a key component in almost every electronic circuit. Download microcontroller 8051 projects, ebooks, tutorials and code examples. Porta pins 0,1,2,3 of stm32 microcontroller are used as output pins. And optocoupler will be triggered by the active low signal.
The required current to run the relay coil is more than can be supplied by various integrated circuits like opamp, etc. Switch s1 is used to test the relay driver circuit. This article describes a diy programmable relay switch using pic16f1847 pic16f628a can also be used microcontroller. Phillips p89v51rd2 microcontroller programmer circuit raspberry pi sim300 module uln 2003 interface with 8051 microcontroller uln2003 relay driver ic use of port of 8051 microcontroller about 162. Relay interfacing with pic microcontroller pic16f877a circuit digest. Make this solidstate relay driver circuit for microcontroller. Now a question arises, why do we need the extra bit of circuit to drive the relay. It is not a good idea to use relay for stepper motor driving. Connector provided for external power supply if needed. Power saving relay driver circuit for microcontroller, the switching activity is performed by a relay, which activates an external load.
How to make relay switch circuit engineering projects. The transistor is typically and solely employed for operating the relay in response to the commands received from the preceding control stage. How to interface relay with pic16f877a pic development board. The driven relay can then operate as a switch in the circuit which can open or close, according to the needs of the circuit and its operation. In the above schematic pic16f877a is used, where on the port b the led and transistor is connected, which is further controlled using the tac switch at rbo. Low voltage relay driver this low voltage relay driver circuit constructed by using ic max 4624. You may recall the tlc555 relay driver circuit that i recently posted, it too is a low side driver. When the relay is at rest no voltage applied to the control circuit, the.
It can be used as a switch and can also be used as voltage regulator. Often a need arise to interface output of the microcontroller with an electromagnetic relay emr. The controlled device may be a heater, a lamp, a computer or a motor. I am guessing that the capacitor in the circuit is designed to prevent a continuous current through the relay coil. A transistor with collector current i c bigger then the above calculated value 60ma, is used in a switching circuit. But, for this purpose the circuit requires relays, acting as controlled switches for different circuits different types of relays are used. For some projects, youll want to use a microcontroller to switch higher voltages, like the 110v north america or 220v pretty much everywhere else running your house lighting or other commercial. Relay driver circuit using uln2003 featured image in general, while designing electronics projects the loads are controlled switched on or off using microcontroller block.
Relay isolates low power circuits from high power circuits. This is where, the next item comes is a power transistor. Arduino relay control latest free electronics projects. Relay interfacing with pic microcontroller pic16f877a. Signal information can be transmitted by the device while maintaining a high degree of electrical isolation between input and output. Pic controlled relay driver this circuit is a relay driver that is based on a pic16f84a microcontroller. Complete circuit for connecting relay with pic microcontroller is given below. Power saving relay driver circuit for microcontroller. A relay should not be directly connected to a microcontroller, it needs a driving circuit due to the following reasons.
I have put together the following circuit to drive some 12v pumps from a microcontroller using a uln2003, but it has a few issues. Contact forum projects experiments circuits theory blog pic tutorials time for science rss site design. Probably not, and even if it is, it is not a good idea to directly drive the relay from a microcontroller. When using logic signals to control a relay, a driver circuit must be used to boost the current needed to energize the relays. Vdd and vss of the pic microcontroller is not shown in the circuit diagram. Ultrasonic water level controller using 8051 microcontroller.
How i will connect the relay across d1 as shown in the circuit. The transistor is driven into saturation turned on when a logic 1 is written on the port pin thus turning on the relay. There should be no connection between your logic circuittransistor to any of the nonccom pins of the relay, only the coil pins. Depending on the signals received from the microcontroller or other control circuits the relay controls the load.
I mean which pin of relay there are 5 in total will be connected to the two terminals of the diode as shown in the above figure and which two pins will be connected to a dc motor so. Arduino projects electronics projects circuits diy. High efficiency relay driver electronics forum circuits. The board includes four relays so this lets us to control four distinct electrical devices. In this circuit diagram, the pic microcontroller is providing a signal to 4 relays through relay driver ic uln2003. It is used to switch high loads or loads that needs ac current to operate. A relay is a type of switch that provides connection between a low power circuit and a high power circuit. How much current does the relay coil require and what is its resistance. An actualsize, singleside pcb for the powersaving relay driver is shown in fig.
Here is a simple microcontrollerrelay interface circuit with perfect galvanic isolation. Microcontroller interfacing with relay rickeys world. Browse other questions tagged microcontroller relay 12v darlington or. Relay driver circuit using npn transistor is given below. Interfacing relay with pic microcontroller mikroc electrosome. Build your mbed projects with development boards for arm cortex processors and mcus.
Here the ground refers to the negative line for an npn and the positive line for a pnp bjt. In general, while designing electronics projects the loads are controlled switched on or off using microcontroller block. Relay is used in all the home automation projects to control the ac home appliances. This circuit is a relay driver that is based on a pic16f84a microcontroller. Relays are devices which allow low power circuits to switch a relatively high current andor voltage onoff. Referring to the above circuit diagram we see that the configuration only. I have block diagram of microcontroller with pwm interfacing with relay through relay driver circuit. Not suitable for battery power applications utilized by the relay. Here is a simple solidstate relay driver circuit using a transistor. Uln 2003 relay driver circuit for 8051 microcontroller. How to drive a relay using microcontrollers vishnus blogs. Complete circuit for connecting relay with pic microcontroller is given below in the above schematic pic16f877a is used, where on the port b the led and transistor is connected, which is further controlled using the tac switch at rbo. Galvanic isolation says that the driver circuit is separated from the signal. Relay with microcontroller schematic cny171 from vishay semiconductors is an optically coupled pair consisting of a gallium arsenide infrared emitting diode optically coupled to a silicon npn phototransitor.
The input is taken from the microcontroller pins and the output corresponding to each input is given to the 5. A microcontroller will not able to supply current required for the proper working of a relay. A simple water level controller using ultrasonic range finder module and 8051 microcontroller is. Using the output pulse from a microcontroller or digital gate ics. Pic controlled relay driver using pic microcontoller. So you need a helper, use a transistor to switch high current to drive the coil instead. The circuit diagram of the ssr driver for the microcontroller mcu is shown in fig. Drivers, relays, and solid state relays drivers, relays, and solid state relays. Relay driver from microcontroller electrical engineering. Microcontroller used in the project is stm32f103c8t6. The whole setup is shown in the block daigram of attached file.
Relay i am using here is of 12v, i am using this one because its mostly used in projects. Driving relays with stm32f103 microcontroller using. Relay driver circuit using uln2003 microcontrollers lab. High side toggle switch driver, low side toggle switch driver, bipolar npn transistor driver, darlington transistor driver, nchannel mosfet driver, and uln2003 driver. A relay driver ic is an electromagnetic switch that will be used whenever we want to use a low voltage circuit to switch a light bulb on and off which is connected to 220v mains supply. Relay driver circuit using uln2003 and its practical applications in microcontroller based projects, how to relay driver circuit uln2003 with stepper motor. A relay driver is nothing but an additional transistor stage attached with the relay which needs to be operated. About 8051 microcontroller and its working with various projects and applications. Arduino high voltage driver circuit using irf9540 power mosfet. As we know that pin of arduino or any microcontroller cannot handle current more then 40 ma thus, we have to design a simple switch circuit.
Tube lights are most used light source and here tube light connection circuit and wiring diagram given with explanation. However if you are controlling the relay with a microcontroller presumably you can program it to supply a short pulse and dispense with the capacitor. Driving relays with stm32f103 microcontroller using uln2003 relay. Interfacing relay to microcontroller dna technology.
Uln2003 is a relay driver ic consisting of a darlington array. The maximum current that a89c51 microcontroller can sink is 15ma while a relay needs about 50 100ma current. For detailed working of relay please visit this page. Electromechanical relays interfacing circuits with. Relay driver circuit using ic uln2003 and its working. Aug 12, 2017 in this article we will comprehensively study a transistor relay driver circuit and learn how to design its configuration by calculating the parameters through. Basic transistor relay driver, actuated on high input npn this circuit will drive a relay coil from a low power output, usually from an ic like 555 or a ttlcmos. In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated. Relay driver circuit using uln2003 and its applications. Hence, arduino uno, which is an atmega 328p microcontroller based prototyping board, is used in the project. The coil of the relay needs a large current around 150ma to drive the relay, which an arduino cannot provide. The input is taken from the microcontroller pins and the output corresponding to each input is given to the 5 relays on the output. As mentioned in the project introduction, a microcontroller is used to drive the relay.
For my garage door opener projects, i was merely using a relay to push a button, so the relay merely switched a low voltage circuit. A transistor works best as a switch when it is connected with a common emitter configuration, meaning the emitter of the bjt must be always connected directly with ground line. You can connect the output of a control circuit, such as a microcontroller, to con2 for controlling the relay circuit. Relay interfacing with microcontroller using uln2003a. The relay driver circuit using uln2003 is given below. Relay is used in all the home automation projects to control the ac home appliances circuit diagram. Microcontroller provides high or low input signals to npn transistor. It prevents the circuit from any back emf generated by the relay coils. In this 3channel relay driver circuit, we have used an optocoupler to trigger the npn transistor which further drives the relay.
In this project we will interface a relay with pic microcontroller pic16f877a and control a 220v ac lamp using the relay. Microcontroller boardscontrol the relay operations by using pic16f18f slicker board. As you can see an npn transistor bc547 is being used to control the relay. It is made up of seven open collector darlington pairs with common emitter. Here we have used a 12v 10amp relay in this pcb board, you can also use 5v relays. A relay should not be directly connected to a microcontroller, it needs a driving circuit. Npn transistor provide high driving current to electro mechanical relay through 12 volt external power supply. It is activated by energizing a coil wounded on a soft iron core. Relay driver circuits electronics projects circuits.
1059 458 196 1229 1308 1264 1327 1501 817 1104 1207 1439 863 1454 1519 1493 173 1481 402 948 197 837 797 1278 1305 1277 614 984 1232 330