2n4401 relay driver circuit

These characteristics make it suitable for driving the coil of a small relay of 24vd. The relay driver circuit using uln2003 is given below. The required current to run the relay coil is more than can be supplied by various integrated circuits like opamp, etc. If you can reverse the sense of the comparator reverse its inputs, so that the relay is on when the comparator is off all you need is to connect an npn transistor like a 2n3904 or 2n4401 emitter to ground, base to. Can someone draw a small circuit showing me the transistor the resistors required. The basic transistor relay driver circuit is shown in fig. One channel relay driver using bc547 transistor circuit.

The circuit and 9v will work fine and will pull the relay between 7 and 9 volt, the only thing to watch for is the working voltage of c2. A 2n4403 pnp transistor is used at the output of the ic to drive an spdt relay switch. The capacitor and resistor in series acts as the transient voltage suppressor to suppress voltage spikes. A relay driver is nothing but an additional transistor stage attached with the relay which needs to be operated. Simple transistor relay circuit transistor as a switch youtube. The npn complementary for the device is 2n4400, 2n4401. See figure 15 and figure 16 for the pinout drawing and schematic symbol of the transistor. Fig 3 is using tip122 to replace 2n4401 with a load resistance of 11. The circuit has only one transistor with a relay as load at its collector. It is similar to others i have seen, though it appears to have two extra parts that others do not have. 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.

Alternating onoff control circuitsan a place of huge collection of free circuits diagram and projects for everyone. A small amount of current on the base pin closes a circuit between the collector and emitter pins. Interfacing relay to microcontroller dna technology. Switching time equivalent test circuits scope rise time circuits to switch a relatively high current andor voltage onoff. The circuit is simple but really efficient and works the best.

Instead, use it to turn on a driver transistor that has lots of gain like the 2n4401. The function of relay driver circuit is to provide the necessary current typically 25 to 70ma to energize the relay coil. In this project the npn transistor 2n2222 drives the relay when the npn junction gets saturated. It consists of a relay, a transistor and some passive devices like resistors, capacitors and switches. And, the input current at output of a normal digital circuit is about 2 ma. We, again, feed the ac relay the ac voltage it is rated for. The zeners are massive overkillnormal commercial practice is to use a single diode something like a 1n4007 connected across the coil,so that as far as the power supply is concerned,it is reverse biased.

Do not operate the circuit without the diode properly connected across the coil. If driving via cmos logic, an enhancement mode mosfet is a good choice fig 5. Dec 9, 2017 arduino high voltage driver circuit diagram. Well assume the relay coil has a dc resistance of 50. Fig 4 uses two 2n4401 connected as darlington pair with 3v battery and rl of. The relay circuit driver uln2003 has a wide range of applications in real life. The device is housed in the to92 package, which is designed for medium p. I mostly understand how it works, but i would like to. This tutorial will guide to to make simple circuit using npn transistor as a switch to turn on electrical appliances using relay. I want to use raspberry pi gpio pins to control a few relays. Galvanic isolationmeans an isolation between two circuits, i. Arduino high voltage driver circuit diagram tehnologie. I was planning to use a 3904 npn transistor with a 330 ohm resistor on the base of the 3904. High side toggle switch driver, low side toggle switch driver, bipolar npn transistor driver, darlington transistor driver, nchannel mosfet driver, and uln2003 driver.

So i put the much heftier 2n4401 in the circuit and did the measurements again. We can now calculate resistor r1 in the circuit as follows. It appears that you intend to drive the base from a 5v signal. Bc547 is a npn transistor hence the collector and emitter will be left open reverse biased when the base pin is held at ground and will be closed forward biased. Need help calculating resistance for transistor base. The operating voltage of the circuit is 9v to 12v dc but it can also be operated on a low voltage 3v6v. For low power relays, a 2n4401 is a good choice fig 3. From relays to bipolar junction transistors hackaday. You can calculate a limiting resistorsr from the input voltage and current. The transistor allows you to control a circuit thats carrying higher current and voltage from the microcontroller. The ac relay driver circuit we will build is shown below. The transistor is driven into saturation turned on when a logic 1 is written on the port pin thus. Automatic water level controller 2 circuits choice. Because the circuit in figure 2, 3 and 4 will run when the output from the digital circuit is fed in to the input is high state or logic high.

One channel relay driver using bc547 transistor 24082016 raj sharma 2 comments single channel relay project is a simple and convenient way to interface a relay for switching application in your project. Pic 16f54 needs to drive a 5v relay i am using a pic 16f54 and need to trigger a 5v relay. The npn bipolar transistor is designed for use in linear and switching applications. The coil of the relay needs a large current around 150ma to drive the relay, which an arduino cannot provide. The tip120 is a npntype transistor, which means the collector will connect to the motor, and the emitter will connect to ground. A circuit purporting to be a relay driver that was published in a recent. The sensitivity of the circuit can be adjusted with the 100k. Arduino high voltage driver circuit diagram arduino. Electronics tutorial about the relay switch circuit and relay switching circuits used to control a variety of loads in circuit switching applications. Leds on or off by using a transistor in its saturated or cutoff state. The yield output of the cd4017 is not sufficient to operate the relay because of which we have utilized a transistor to drive the relay. In reality a transistor is generally added to the circuit to provide enough power to control the relay, while a diode protects the transistor from the. The transistor is typically and solely employed for operating the relay in response to the commands received from the preceding control stage.

I would add a driver transistor with a clamp diode across the coil. Jun 5, 2018 arduino high voltage driver circuit diagram. The spdt relay should be in accordance with the operating. One 2n2222 transistor code lock system is a simplest electronic code lock system. Some of the major applications associated with uln2003 are given below. Relay driver circuit using uln2003 and its applications. I used the npn transistors 2n4401, 2n3904 and 2n4124, and the pnp. Now a question arises, why do we need the extra bit of circuit to drive the relay. Acdc led drivers 54 dcdc led drivers 36 linear led drivers 55 motor drivers. In the circuit below is most transistor relay driver circuit.

Complete technical details can be found at the datasheet give at the end of this page. Npn switching transistor, 2n4401 datasheet, 2n4401 circuit, 2n4401 data sheet. Try to get the resistor, transistor, diode and relay working before you attach to arduino. On the relay driver, you do show the clamp diode across the phototransistor it should go across the relay coil. Packaging type marking code basic ordering unit pieces t93 3000. Philips, alldatasheet, datasheet, datasheet search site for electronic components and. The diode protects the transistor from the large inverse spike. If we use a relay with a rated voltage of 110vac, we must feed it 110v from an ac power source. Repair williams system 11 pinball 19861990, part one.

This is an automatic water pump controller circuit project. Here is a simple microcontroller relay interface circuit with perfect galvanic isolation. All about 2n2222 transistor and its circuit diagrams. Symbol parameter conditions value unit rthja thermal resistance from junction to ambient note 1 200 kw.

Referring to the above circuit diagram we see that the configuration only. In this circuit diagram, the pic microcontroller is providing a signal to 4 relays through relay driver ic uln2003. So, my guess is the relay needs a current of 563 79ma. To connect a 12v relay to the arduino you need the following things. Npn switching transistor 2n4401 thermal characteristics note 1. As you can see an npn transistor bc547 is being used to control the relay. Drive relay by digital circuit circuit wiring diagrams. The one youre using for this lab is an npntype transistor called a tip120. If you desire to drive a larger relay or want less base current, a darlington driver fig 4 is recommended.

Sound sensor switch circuit using lm393n dual comparator ic. Transistor mounted on an fr4 printed circuit board. You may recall the tlc555 relay driver circuit that i recently posted, it too is a low side driver. As well as the standard common emitter configuration for a relay switch circuit, the relay coil can also be connected to the emitter terminal of the transistor to form an emitter follower circuit. The relay coil voltage and the transistor voltage must add up to the power supply voltage 10v in this case. Transistor switches can be used to switch a low voltage dc device e. Presently in the contrary circumstance when the output at the pin 2 goes high it will enact the relay through the 2n4401 transistor, and the output at pin 3 goes low and the led 1 becomes deactivated. Relay switch circuit and relay switching circuit electronicstutorials. Relay driver circuit using ic uln2003 and its working. The device is housed in the to92 package, which is designed for medium.

You can easily redesign the relay pads on the pcb for the relay of your choice. When used as an ac signal amplifier, the transistors base biasing voltage is applied in such a way that it always operates within its active region, that is the linear part of the output. The bc547 is a cheapaschips general purpose npn transistor, which has a collector current of 100ma maximum, and a collectortoemitter voltage of 65vdc maximum. While our transistor switch can easily replace many mechanical relays, it does have a few drawbacks. The input signal is connected directly to the base, while the output is taken from the emitter load as shown. Using a transistor to control high current loads with. Transistor relay driver circuit with formula and calculations. The opto coupler may not have sufficient ctr current transfer ratio to drive the relay coil. Turning on relay ac to test both coilsflashers that driver transistors q22q25 and q30q33 control.