Since reed switches are sealed, water contact is avoided and the system works infinitely without any issues. 0000145131 00000 n Reed switch also called reed relay, is a low current magnetic switch with a concealed pair of contacts that close and open in response to magnetic field near it. Your email address will not be published. 0000046864 00000 n Relays allow one circuit to switch a second circuit which can be completely separate from the first. Reed switch was invented way back in the year 1945, by Dr. W.B. COTO TECHNOLOGY PROVIDES RELAYS, SWITCHES & SENSORS REDROCK® TMR TECHNOLOGY MAGNETIC SENSORS & SWITCHES Using proven TMR (Tunneling Magnetoresistance) technology, the high-performance RedRock™ RR111 analog TMR magnetic sensor series, the RR121 & RR122 digital sensor series, and the RR131 digital switch series have numerous technologically-advanced … Release Voltage Max. xref In the schematic, trimmer-potentiometer is 5k, but actually I put 10k, after consulting with the datasheet of the LCD module I bought. This is the terminal of the relay where you connect the first part of your circuit to. Reed relays contain a reed switch, a coil for creating a magnetic field, an optional diode for handling back EMF from the coil, and an encapsulating package with connection terminals. Typically, a resistor capacitor protection network is applied as indicated in figure C, in case the supply is an AC. 0000002765 00000 n 0000005173 00000 n Circuit Layout: Reed relays, as with any relay, use an electromagnetic coil and sometimes magnets to actuate the reed switch contacts. On the contrary, a reed switch as a result of its gold-plated contact surfaces and inert atmosphere works successfully for over a billion operations without any issues. ��� ��T��`�U�Cʮ�S�In�6�5�c���et"�Ђ6 m����ˁ�V�(�u�c��n�ܡ�Z�5z�M�[^exv���) ��s�R�+!�� ����Pc��H�Lsg(�pE�d���5H^�_�4. 0000008437 00000 n E.g. The Coto Classic™ Reed Relays Line is composed of a wide range of relay types for a multitude of applications. The basic working of a reed switch can be understood from the following explanation. 0000019822 00000 n They have some parameters that can affect the operation of the circuit, and if the right reed relay is to be chosen, its specification needs to be understood. The reeds close if a magnet is held close to the device body. For reed relays, however, the contacts are much smaller and lower mass than those used in electromechanical relays. A relay is an electrically operated switch. 0000019752 00000 n endstream endobj 370 0 obj <>/Metadata 10 0 R/Outlines 4 0 R/Pages 9 0 R/StructTreeRoot 12 0 R/Type/Catalog/ViewerPreferences<>>> endobj 371 0 obj <>/Font<>/ProcSet[/PDF/Text/ImageC]/XObject<>>>/Rotate 0/StructParents 0/TrimBox[0.0 0.0 595.276 841.89]/Type/Page>> endobj 372 0 obj <> endobj 373 0 obj <> endobj 374 0 obj <>stream Switching rates can be adjusted one second to well over 2000 per minute simply by changing the rotating disc speed. In one of the practical tests in a reputed USA company lab, four reed switches were powered with 120 ON/OFF sequences per second through a load working with 500 micro-volts and 100 microamps, dc. The ersistor can be replaced with a capacitor also for enabling a similar kind of protection, as shown in figure B. They have faster switching speed compared to the electromechanical ones but their switching current and voltage is lower mainly because of its contacts thickness. But, there may be certain applications in which the reed may be required to be 'normally-closed' or switched ON, and switch OFF in the presence of a magnetic field. This method has been proved to be the most effective, and has been successful in keeping the reed safe from motor starter switching for over a million operations. Reed Relays, consider an example using the three-relay matrix of 5-V SIL relays in Figure 2b on 0.20“ centers (no magnetic shielding). Transformer Winding Counter: Here, the reed switch is operated by a magnet attached on a rotating winder wheel, which allows the counter to get a clock signal for each winding rotation from the reed activation. In some models of security alarm systems, reed relays are used. h�b```f``��������A�X��,�10����Z. 0000017820 00000 n In figure C we can see a diode connected across the reed. 0000010688 00000 n Sealed in a long, narrow glass tube, the contacts are protected from corrosion. The reed switch is a simple device and relatively low cost to manufacture. 0000011742 00000 n 2017. The following image explains the situation clearly. The significant factor to guard against is the release of energy, temporarily stored in the coil, at the time the reed switch opens. 0000015281 00000 n However, you may find several programs where both the magnet and the reed has to be positioned over a fixed platform. This can be a significant problem when a regular switch is used. 419 0 obj <>stream If you have any circuit related query, you may interact through comments, I'll be most happy to help! The relay in the circuit has a coil rated for 9 VDC and a switch rating of 10 A at 117 VAC. 0000044075 00000 n Reed switch also called reed relay, is a low current magnetic switch with a concealed pair of contacts that close and open in response to magnetic field near it. The following figure shows different linear planes of operation for a reed switch. The maximum tolerable value is specified for purely resistive loads. HE3600 Miniature SIL Relay Littelfuse HE3600 Miniature SIL Relay is a reed relay with normally open or data switching contacts capable of switching up to 200V DC at 10W. Last Updated on April 29, 2020 by Swagatam 3 Comments. Relay basics Reed relay Reed relay specs Relay circuits Solid state relay Reed relay specifications are different to those of other components normally found in electronic circuits. Fundamentally, a reed switch is a magneto-mechanical relay. 0000001850 00000 n To be more precise a reed switch working is initiated when a magnetic force is brought near it, which results in the required mechanical switching action. A reed switch consists two reed contacts, typically made from nickel-iron and then plated with materials to ensure the maximum life to the device. This UL-recognized device is available with 5V, 12V, and 24V coils. Now that we know what each terminal pin represents, we now wire it to a circuit … 0000126423 00000 n In figure A and B, the reed switches are installed in a fixed position, while magnets are attached with the rotating disc which causes the magnets to move past the reed switch on each rotation, switching the reed ON/OFF correspondingly. The reed switch is composed of two overlapping ferromagnetic blades (called reeds) hermetically sealed within a glass capsule that is filled with an inert gas. Coil Voltage When a magnetic field is introduced near a reed switch either from a permanent magnet or from an electromagnet, the reeds being ferromagnetic turn into a part of the magnetic source. The glass envelope may contain multiple reed switches or multiple reed switches can be inserted into a single bobbin and actuate simultaneously. 0000002651 00000 n This will create some noise that upset the sensors attached to the micro-controller. Activation of the reed through a rotational movement can be also implemented successfully. The outer two relays are activated with 5 Order Now! Gate Open/Close Controller: Reed switches also work great as solid state limit switches. 0000011374 00000 n The contacts are concealed inside a glass tube and its ends terminated out of the glass tube for external connection. 0000126836 00000 n 369 51 � l���0�d�������=��y,�����{�O1h3��90�aL�pb����$b/����5PM�{��V�[73�|�Ҍ@�Ĭ@~X�A�����Uh3T�V� �P3 Non-standard package sizes and pinouts, custom coil and shielding designs, and multi-pole configurations are common variables. 0000000016 00000 n Relays – Reed Relays are in stock at DigiKey. 0000125892 00000 n 0000017329 00000 n In this gate controller circuit, the reed switch limits the gate opening or closing by shutting off the motor whenever the gate reaches its maximum sliding limits. How to Build a Reed Switch Circuit. Calculating Inductors in Buck Boost Converters, How to Make Adjustable Current Limiter Circuits, Small Signal Transistor(BJT) and Diode Quick Datasheet, Temperature range = -55 degrees C to +150 degrees C, Life at zero load = 500 x 10^6 operations. ]豙!`������ �`#�jpY~����8=�f���̸��VU0e��R��1���e$$������ɓﾑ�LM]��OV�� �s����ߗ Y� As we know that hysteresis is a phenomenon in which the system is unable to activate and deactivate at a particular fixed point. The reeds are clamped firmly on either ends of the glass tube in such a way that their free ends are slightly overlapped at the center with a separation of approximately 0.1 mm. Coil operated relays or solenoid control valves possess considerable inductive values. The reed switch is an electrical switch operated by an applied magnetic field.It was invented in 1922 by a professor at Leningrad Electrotechnical University, and later evolved at Bell Telephone Laboratories in 1936 by Walter B. Ellwood into the reed relay. On the other hand, the same concept can be applied for getting exactly the opposite results. If the relay is powered and the switch is closed, COM and N.O. In situations where the negative peaks are high, the reeds may switch ON/OFF several times as the magnet moves past across the end to end length of the reed. There are normally open reed switches and normally closed reed switches. Legacy Printed Circuit Board & Reed Relays. Although this may slightly increase the idle current flow in the reed but that won't harm the reed anyway. Moreover, reed switches are cheap and therefore become suitable for all types of electrical, electronic applications. 0000006293 00000 n It is assumed that the ideal reed switch load is a Resistive Load, but it is almost impossible to reduce any load to purely resistive.Therefore, when a Reed Switch is to be connected to an Inductive load or a load where Inrush Current flows (such as a Capacitive Load or a Lamp Load), contact protection circuits are required, in order to increase the life of the reed switch. Although extremely efficient, reed switch may show a tendency to fail if the operated under higher current inputs. As soon the external ferrous agent is moved between the reed and the magnet, the magnetic force gets enhanced and reinforced by the ferrous agent which instantly pulls-in the reed switch and activates it. The coil current can be on or off so relays have two switch positions and most have double throw (changeover) switch contacts as shown in … If the load is capacitive or inductive, in that case the contacts of the reed switch must either be substantially derated or appropriate snubber protection and reverse EMF protection applied across the reed terminals, as shown below: Any of the above four simple methods an e employed for enabling protection to a reed switch from inductive or capacitive current spikes. 0000010252 00000 n 0000004780 00000 n And with around a billion operation specification, the functional life of these devices also look very impressive. This can easily be achieved either by biasing the device with a complementing nearby magnet as demonstrated below, or by using a 3 terminal SPDT type of reed switch as indicated in the second diagram below. For an inductive load such as a relay coil with a DC supply, a simple resistor shunt rated at 8 times more than the relay coil will be just enough to keep the reed relay safe from the relay coil back EMFs, as shown figure A. During the sealing process the air inside the tube is pumped out and is replaced by dry nitrogen. Therefore, the distance of the fixed magnet must be experimented with some trial and error until the right differential is achieved, and the reed activates sharply at a fixed point by the moving magnet. The gate current being significantly less than the load current, the reed switch will work efficiently and allow the triac to be switched wit the high current load. I am making a relay driver for output 220VAC 10A. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. Reed switches have been manufactured since the 1930s Reed switches are designed to have extremely high working life span which may be range from 100 million to 1000 million open/close operations. Magnetic Door Alarm: In this application, a reed switch activates or deactivates when an adjacent magnet is moved by the opening or closing of a door. Relays ship same day ... comprehensive electronic symbol library and an integrated Digi-Key component catalog to design and share electronic circuit … %PDF-1.4 %���� The alarm alerts the user regarding the operation of the door. There are 2 basic types of reed switches. The above hysteresis issue can be reduced to a geat extent by simply introducing another magnet with an inverted N/S poles at the opposite side of the reed switch, a shown below: Make sure that the left side fixed magnet is not within the pull-in range of the reed switch, rather at some distance away, otherwise the reed will remain closed and will open only when the right side magnet is brought too close to the reed. 0000004363 00000 n If you continue to use this site we will assume that you are happy with it. Even minute reed switch can be applied here, and will work without issues. Reed Relays are available at Mouser Electronics from industry leading manufacturers. It’s my pleasure, Glad you liked the post! In the test each of the reeds could complete 50 million closures consistently with not a single occasion showing a switched resistance beyond 5 ohms. 0000126161 00000 n 0000017302 00000 n Operating Voltage Min. endstream endobj 418 0 obj <>/Filter/FlateDecode/Index[12 357]/Length 34/Size 369/Type/XRef/W[1 1 1]>>stream 0000001342 00000 n I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. In a Reed Relay the magnetic field is generated by an electrical current flowing through an operating coil which is fitted over "one or more" Reed Switchs. 0000011487 00000 n 0000109715 00000 n The value R and C can be determined through the following formula, C = I^2 / 10 uF, and R = E / 10I( 1 + 50/E). Standex Electronics is the leading global reed relay expert. 0000016335 00000 n We use cookies to ensure that we give you the best experience on our website. This protection works well in DC circuits with inductive load, although the polarity of the diode must be correctly implemented. 0000012221 00000 n These relays are well suited for use in automated test equipment, security, medical, and process … startxref Input for relay is 5VDC and isolated with optocoupler (MOC3021). So actually it is not due to melting of the contacts, rather the shorting due to the collection of the eroded particles that causes the reed contacts to seem like they have melted and fused. Circuit Diagram of Connecting Reed Switch with Arduino Dry reed relays are made of coils wrapped around reed switches. 0000015144 00000 n This causes the ends of the reeds to acquire opposite magnetic polarity. All testing will be performed on the center relay which has an actual pull-in voltage of 2.6 V by itself. Thus, only 9 VDC passes through the handheld pushbutton. Reed relays contain a reed switch, a coil for creating a magnetic field, an optional diode for handling back EMF from the coil, a package and a method of connecting to the reed switch and the coil to outside of the package. High current causes the contacts to erode which is also commonly seen in regular switches. The optional 0.1 uF and the 100 ohm RC is a snubber network is for protecting the triac against high current inductive spikes, if the load is an inductive load. 0000126450 00000 n Float Switch: Reed switches can be used for effective corrosion free float switches water level controllers. However, selecting the magnet can be rather crucial if the mode of operation is across the b-b plane. A reed relay is a type of relay that uses an electromagnet to control one or more reed switches. 0000001665 00000 n This is crucial to ensure that the contacts work in an inert atmosphere which helps to keep the contacts corrosion free, eliminate air resistance, and make it long lasting. In the majority of systems in which a reed switch is operated through 'a permanent magnet, the magnet is installed over a moving element, and the reed is installed over a fixed or constant platform. Reed Relays are available at Mouser Electronics from industry leading manufacturers. As an example, for a 12 V electrical relay, the activation point may be 11 V, but its deactivation point may be somewhere around 8.5 V, this time lag between the activation and deactivation points is known as hysteresis. 0000019920 00000 n 0000072703 00000 n Typically, a reed switch will close when the magnet is brought at a distance of 1 inch from it, but it may need the magnet to be moved around 3 inches away to open the contacts to its original form, due to magnetic hysteresis. 0000109547 00000 n If we move the magnet across any of the planes a-a, b-b, and c-c, will allow the reed to operate normally. COM- This is the common of the relay. 0000012470 00000 n [�C�˒�APP����$-����A�dЇbiƯ��lʌm�y�)�݌ However, the whole controlling circuit is using same 5V power (HL PM05) and used common ground for driving the Relay. Similarly, for a reed switch, the deactivation of its reeds may require the magnet to be moved much farther away from the point at which it was initially activated. Rotary motion may also be used to actuate a reed switch, In A and B the switches are stationary and the magnets rotate. In examples C and D both the switches and the magnets are stationary and the switch operates whenever the cutout portion of the magnetic shield is between magnet and switch. Catalog . 0000006672 00000 n The basis of any reed relay is the reed switch itself - this is the core element of the reed relay. 0000005556 00000 n Both these devices produce a magnetic field around them to actuate the reed switch(es). Based on the status of the switch (which Arduino reads continuously), an LED connected to the Arduino UNO will be activated. In this post we comprehensively learn about reed switch functioning, and how to make simple reed switch circuits. ø�K�f{����E�i���Ys�bP�.Grb9�%c�ma ���8�QF���:�Խc����Q6�����Y��x�t�B�B7!�s��V����2�=A���u�;�S�j�r���*���� Courtesy of Steven Engineering, Inc - (800) 258-9200 - sales@steveneng.com - www.stevenengineering.com 0000163515 00000 n This is because of lack of adequate current to eliminate the resistive surface layer normally associated with standard switch contacts. I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. We are the world's largest reed switch manufacturer.Our high quality reed switches are the core switching element in the Reed Relay. 0000018755 00000 n The reed switch contacts overlap so that when they close they make contact with each other. To achieve this, you can use among the many set ups shown below: It is also possible to use a rotational motion for triggering a reed switch set up. diving a high current load via a 2 transistor Darlington. Ellwood, while being employed at the Western Electric Corporation, in the USA. Previous: Elementary Electronics Explained, Next: LM4862 Amplifier Circuit – A Better LM386 Alternative. A relay is an electrically operated switch.Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. 0000002011 00000 n General Purpose DIP Reed Relay Schematic View Features • Industry standard 14-Pin DIP Package • High speed and low drive power • Optional coil suppression diode Contact Form: 1 Form C (SPDT) / 2 Form A (DPST-NO) Coil Data Nominal Coil Voltage Nominal Coil Resistance Max. 0000044338 00000 n A great advantage of the reed switch is its capacity to work very efficiently while switching low magnitudes of currents and voltages. Whenever the Reed Switch gets activated (when a magnet is placed nearby), the Input pin of the Arduino changes its state to LOW. The reed switch … This erosion results in tiny particles which are also magnetic to collect near the gap of the contacts and somehow create a bridging across the gap. 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Coil rated for 9 VDC and a switch rating of 10 a 117... As indicated in figure C we can see a diode connected across the reed switch circuits without issues... Crucial if the operated under higher current inputs LM386 Alternative or back EMF experience on website... Coto Technology, Magnecraft, MEDER, TE Connectivity & more to erode which is also seen... Idle current flow in the year 1945, by Dr. W.B for relay is powered and the magnets.. My comment non-standard package sizes and pinouts, custom coil and sometimes magnets to actuate a switch. Glass tube and its ends terminated out of the gap causes a voltage or! That we give you the best experience on our website mass than used... Arduino UNO will be performed on the other hand, the functional life these..., where i love sharing my innovative circuit ideas and tutorials has a coil for! In case the supply is an authorized distributor for many reed relay manufacturers including COTO Technology Magnecraft... And 1 uF the factory or your local COTO representa-tive Note reed switch any.. Load, although the polarity of the switch contacts water contact is avoided and the acts! Lm386 Alternative maximum tolerable value is specified for purely resistive loads, selecting the magnet and the capacitor be... At a particular fixed point actual pull-in voltage of 2.6 V by.. An electromagnetic coil and sometimes magnets to actuate a reed switch was invented to eliminate reed relay schematic resistive surface normally! Noise that upset the sensors attached to the electromechanical ones but their switching current voltage... Are happy with it hobbyist, inventor, schematic/PCB designer, manufacturer https: //www.homemade-circuits.com/, where i love my. Sealing process the air inside the tube is pumped out and is replaced by dry.! And isolated with optocoupler ( MOC3021 ) a pair of flattened ferromagnetic strips ( reeds ) which are sealed... Relays or solenoid control valves possess considerable inductive values leading manufacturers on the center relay has... There are normally open reed switches are the world 's largest reed switch contacts inductive! And actuate simultaneously this UL-recognized device is available with 5V, 12V, and industrial multiple... Devices also look very impressive collapsing magnetic field, when an inductive circuit is using 5V...