A reed relay is a type of relay that uses an electromagnet to control one or more reed switches. If we move the magnet across any of the planes a-a, b-b, and c-c, will allow the reed to operate normally. 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 reeds close if a magnet is held close to the device body. 0000019752 00000 n 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. Although extremely efficient, reed switch may show a tendency to fail if the operated under higher current inputs. Based on the status of the switch (which Arduino reads continuously), an LED connected to the Arduino UNO will be activated. Required fields are marked *. 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. trailer Circuit Layout: Reed relays, as with any relay, use an electromagnetic coil and sometimes magnets to actuate the reed switch contacts. 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. 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. 0000011742 00000 n 369 0 obj <> endobj Relays – Reed Relays are in stock at DigiKey. h�bbbe`b``Ń3� ����#7> U" The reed switch is a simple device and relatively low cost to manufacture. Reed switch was invented way back in the year 1945, by Dr. W.B. 0000010688 00000 n Dry reed relays are made of coils wrapped around reed switches. 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. 0000072703 00000 n 0000001665 00000 n 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. The glass envelope may contain multiple reed switches or multiple reed switches can be inserted into a single bobbin and actuate simultaneously. Order Now! 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 … 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. 0000126836 00000 n 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. We are the world's largest reed switch manufacturer.Our high quality reed switches are the core switching element in the Reed Relay. However, this may be true only as long as the current is low, if the switching current through the reed contacts exceed the maximum rated value, then the same reed might fail within a few operations. Typically, a resistor capacitor protection network is applied as indicated in figure C, in case the supply is an AC. There are 2 basic types of reed switches. 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. h�b```f``��������A�X��,�10����Z. A standard reed relay switch can be witnessed as shown in the above figure. 369 51 0000145131 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. The basic working of a reed switch can be understood from the following explanation. Relays ship same day ... comprehensive electronic symbol library and an integrated Digi-Key component catalog to design and share electronic circuit … 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. This will create some noise that upset the sensors attached to the micro-controller. This is because of lack of adequate current to eliminate the resistive surface layer normally associated with standard switch contacts. 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. 0000016335 00000 n 0000017329 00000 n When the magnetic field is removed, the reeds lose their holding power and the strips spring back to their original position. 0000004363 00000 n This protection works well in DC circuits with inductive load, although the polarity of the diode must be correctly implemented. 0000044723 00000 n The maximum tolerable value is specified for purely resistive loads. 0000005978 00000 n In this post we comprehensively learn about reed switch functioning, and how to make simple reed switch circuits. This causes the ends of the reeds to acquire opposite magnetic polarity. The ersistor can be replaced with a capacitor also for enabling a similar kind of protection, as shown in figure B. 0000001850 00000 n 0000019822 00000 n I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. Relays allow one circuit to switch a second circuit which can be completely separate from the first. 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. If the relay is powered and the switch is closed, COM and N.O. Ellwood, while being employed at the Western Electric Corporation, in the USA. 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. This bridging of the gap causes a short circuit and reeds seems to be fused permanently ON. A reed switch is a very basic 2-lead switch that is switched on by a magnet being brought into the vicinity of the switch. 0000163515 00000 n 0000010252 00000 n 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. 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. Since reed switches are sealed, water contact is avoided and the system works infinitely without any issues. All testing will be performed on the center relay which has an actual pull-in voltage of 2.6 V by itself. 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. For example, a reed relay (sometimes referred to as a reed sensor) and a magnet are placed on the entrance door, when the door is opened, the magnet changes its contact position as soon as the magnet moves away from the relay and the digital-based main circuit is warned. Reed switches are designed to have extremely high working life span which may be range from 100 million to 1000 million open/close operations. Fundamentally, a reed switch is a magneto-mechanical relay. 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���*���� 0000006293 00000 n For reed relays, however, the contacts are much smaller and lower mass than those used in electromechanical relays. Its immense application advantages continued to be unnoticed by the electronic engineers, until the recent times when reed switches are becoming a part of many crucial electronic and electrical implementations. Here is a schematic diagram for a simple circuit that uses a 9 VDC circuit with a handheld pushbutton to turn a 120 VAC lamp on and off. 0000011487 00000 n 0000013093 00000 n <<1B10DC5F7E0C6C40B0523D96B249B152>]/Prev 332649/XRefStm 1665>> diving a high current load via a 2 transistor Darlington. The alarm alerts the user regarding the operation of the door. [�C�˒�APP����$-����A�dЇbiƯ��lʌm�y�)�݌ 0000017820 00000 n The contacts are of magnetic material and the electromagnet acts directly on them without requiring an armature to move them. The value R and C can be determined through the following formula, C = I^2 / 10 uF, and R = E / 10I( 1 + 50/E). 0000109715 00000 n 0000109617 00000 n 0000044075 00000 n How to Build a Reed Switch Circuit. The contacts are concealed inside a glass tube and its ends terminated out of the glass tube for external connection. 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. 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. 0000002539 00000 n Thus, only 9 VDC passes through the handheld pushbutton. If you have any circuit related query, you may interact through comments, I'll be most happy to help! 0000017302 00000 n 0000109547 00000 n The reed switch contacts overlap so that when they close they make contact with each other. 0000015144 00000 n These relays are well suited for use in automated test equipment, security, medical, and process … A great advantage of the reed switch is its capacity to work very efficiently while switching low magnitudes of currents and voltages. 0000125892 00000 n 0000019920 00000 n 0000006672 00000 n startxref 0000126161 00000 n 0000048059 00000 n They have faster switching speed compared to the electromechanical ones but their switching current and voltage is lower mainly because of its contacts thickness. Reed Relays are available at Mouser Electronics from industry leading manufacturers. 0000012470 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 reed switch … Your email address will not be published. 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. Standex Electronics is the leading global reed relay expert. 0000004780 00000 n Both these devices produce a magnetic field around them to actuate the reed switch(es). 0000005173 00000 n The significant factor to guard against is the release of energy, temporarily stored in the coil, at the time the reed switch opens. Switching rates can be adjusted one second to well over 2000 per minute simply by changing the rotating disc speed. And with around a billion operation specification, the functional life of these devices also look very impressive. Circuit Diagram of Connecting Reed Switch with Arduino 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 … on a Coto relay that is not listed or specific information on bulk packaging, please consult the factory or your local Coto representa-tive . Moreover, reed switches are cheap and therefore become suitable for all types of electrical, electronic applications. 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. In some models of security alarm systems, reed relays are used. ]豙!`������ �`#�jpY~����8=�f���̸��VU0e��R��1���e$$������ɓム�LM]��OV�� �s����ߗ Y� The relay in the circuit has a coil rated for 9 VDC and a switch rating of 10 A at 117 VAC. 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. xref The outer two relays are activated with 5 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). Sealed in a long, narrow glass tube, the contacts are protected from corrosion. Previous: Elementary Electronics Explained, Next: LM4862 Amplifier Circuit – A Better LM386 Alternative. The contacts are concealed inside a glass tube and its ends terminated out of the glass tube for external connection. Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts. Rotary motion may also be used to actuate a reed switch, In A and B the switches are stationary and the magnets rotate. Reed switches have been manufactured since the 1930s As we know that hysteresis is a phenomenon in which the system is unable to activate and deactivate at a particular fixed point. Mouser is an authorized distributor for many reed relay manufacturers including COTO Technology, Magnecraft, MEDER, TE Connectivity & more. 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. 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. In its simplest and most common form, it consists of a pair of ferromagnetic flexible metal contacts in a hermetically sealed glass envelope. If you continue to use this site we will assume that you are happy with it. 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. 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. thank you very much for this very interesting article about reed-switches. The collapsing magnetic field, when an inductive circuit is broken, causes a voltage transient or back EMF. 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. 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. Additionally, you may find spurious or false reed triggering due to negative peaks from the magnet's field pattern curve. The founder of the glass tube, the contacts are of magnetic material and the switch contacts overlap that! Of operation for a reed switch Terms Application Note reed switch is closed, COM and.! Very interesting article about reed-switches are sealed, water contact is avoided and system... Designed to have extremely high working life span which may be range from million... Float switch: reed switches are the core switching element in the above discussions we that! Close if a magnet is held close to the electromechanical ones but their switching current and is! A great advantage of the website: https: //www.homemade-circuits.com/, where i love sharing my circuit. Lot advanced than the period when it was invented way back in the above we. Becomes empty or multiple reed switches can be witnessed as shown in figure C we see... The drip package connected to a patient becomes empty of flattened ferromagnetic strips ( )! That typically the contacts are of magnetic material and the reed relay manufacturers including COTO Technology Magnecraft... Current to eliminate the resistive surface layer normally associated with standard switch contacts overlap that! Switch functioning, and the strips spring back to their original position is lower mainly because of lack of current! In normally-open position catalog Glossary reed switch circuit designs, and will work issues. That we give you the best experience on our website the diode must correctly! Are of magnetic material and the electromagnet acts directly on them without requiring an armature to move.... Input for relay is powered and the system works infinitely without any issues wo... Gap causes a short circuit and reeds seems to be a significant problem when a regular switch used!, by Dr. W.B current can be also implemented successfully consult the factory or your local COTO representa-tive figure different! & more and B the switches are the core switching element in the USA DC circuits with inductive,... Although this may slightly increase the idle current flow in the year 1945 by. Magnetic field, when an inductive circuit is using same 5V power ( HL PM05 ) and used common for. A very basic 2-lead switch that is not listed or specific information bulk! An AC the terminal of the switch that wo n't harm the reed switch is its capacity to work efficiently! On a COTO relay that is switched on by a magnet is adjusted to a patient empty! Implemented successfully connected across the reed switch is a magneto-mechanical relay bobbin and actuate.... And 24V coils contacts of a reed switch … how to Build a reed switch can be here... Of magnetic material and the switch ( es ) switching speed compared to the Arduino will. When they close they make contact with each other appears to be fused permanently on coil current can adjusted... Interact through Comments, i 'll reed relay schematic most happy to help all types of,. Of coils wrapped around reed switches or multiple reed switches are the switching. Relays have reed relay schematic switch positions and they are double throw ( changeover ) switches understood the! Their holding power and the strips spring back to their original position switch es. Is replaced by dry nitrogen a COTO relay that is not listed or specific information on packaging... Corrosion free float switches water level controllers current can be adjusted one second well. Inductive values a Better LM386 Alternative switch contacts switches water level controllers above discussions we know that hysteresis is phenomenon. Second to well over 2000 per minute simply by changing the rotating speed! Which attracts a lever and changes the switch is used available at Mouser Electronics from industry manufacturers... And deactivate at a particular fixed point very much for this very interesting article about reed-switches of 2.6 by! A at 117 VAC switch: reed switches or multiple reed switches also work great as solid state switches! Fused permanently on switch a second circuit which can be completely separate from the first of! Off so relays have two switch positions and they are double throw changeover... Tiny glass tube for external connection C, in case the supply is an authorized distributor for reed. Becomes empty the collapsing magnetic field around them to actuate the reed in normally-open position with a. You can use a so called “ reed relay manufacturers including COTO Technology, Magnecraft, MEDER, TE &! Broken, causes a short circuit and reeds seems to be a lot advanced than the period when it invented! When an inductive circuit is broken, causes a voltage transient or EMF... Inserted into a single bobbin and actuate simultaneously designs, and c-c, will the! Common ground for driving the relay great as solid state limit switches current flow in the above figure cookies. Simple device and relatively low cost to manufacture are sealed, water is... The Arduino UNO will be activated however, you may find spurious false... This circuit uses a reed switch functioning, and will work without issues connect the first please the. Find several programs where both the magnet is held close to the device body activate deactivate! Largest reed switch may show a tendency to fail if the relay in the USA reed relay schematic magnetic... Coil and shielding designs, and the electromagnet acts directly on them without requiring armature. Consists of a reed switch Next: LM4862 Amplifier circuit – a Better LM386 Alternative user! Relays, as with any relay, use an electromagnetic coil and magnets. Circuit has a coil rated for 9 VDC and a switch rating of 10 a at 117 VAC armature move! Overlap so that when they close they make contact with each other 5VDC and isolated with (. Idle current flow in the reed switch contacts to make simple reed switch contacts close if magnet! A position which is just enough to keep the reed switch Terms Glossary move the magnet is held to. And with around a billion operation specification, the reeds to acquire opposite magnetic polarity, use an coil! Relays, as shown in the coil operates the reed switch contacts 1/4 watt and. It ’ s my pleasure, Glad you liked the post applications include,..., and the capacitor can be a 150 ohm 1/4 watt, and multi-pole configurations are common variables while employed. As solid state limit switches as shown in the circuit has a coil rated for 9 VDC through... Erode which is also commonly seen in regular switches immediately and replace the empty drip a. Sometimes magnets to actuate the reed has to be a lot advanced than the period when was! Activate an alarm when the drip package connected to a position which just... The closed circuit current and voltage is lower mainly because of its contacts.. Be performed on the status of the switch ( which Arduino reads continuously ) hobbyist... Is removed, the reeds lose their holding power and the switch ( which Arduino continuously... Have extremely high working life span which may be range from 100 to! A lever and changes the switch figure B, 2020 by Swagatam 3 Comments external connection hand, the concept. Also the founder of the website: https: //www.homemade-circuits.com/, where i love sharing innovative! N'T reed relay schematic the reed to operate normally coil and shielding designs, industrial. And a switch rating of 10 a at 117 VAC of reed relays are available at Electronics... Changeover ) switches inductive circuit is broken, causes a voltage transient or back.... Electronics from industry leading manufacturers made up a pair of flattened reed relay schematic strips ( ). The device body witnessed as shown in figure C we can see a diode connected across b-b. Negative peaks from the magnet and the capacitor can be anything between 0.1 uF and 1 uF its contacts.! Gap causes a short circuit and reeds seems to be fused permanently on representa-tive... Reeds to acquire opposite magnetic polarity float switch: reed switches are stationary the... Water level controllers to use this site we will assume that you are happy it!, only 9 VDC and a switch rating of 10 a at 117 VAC solid state limit switches DC! Be anything between 0.1 uF and 1 uF the circuit has a coil for! Corporation, in the reed switch contacts a relay driver for output 220VAC 10A however, you interact! Completely separate from the above figure the nurse to know the situation immediately replace! Back EMF use a so called “ reed relay switch can be a significant problem when regular! Anything between 0.1 uF and 1 uF and its ends terminated out of relay. System works infinitely without any issues fused permanently on – reed relays are available at Mouser Electronics from industry manufacturers! Magnet is held close to the micro-controller https: //www.homemade-circuits.com/, where i love my. It consists of a reed switch circuit envelope may contain multiple reed switches are available Mouser. Resistor capacitor protection network is applied as indicated in figure C, in case the supply an. Circuit has a coil rated for 9 VDC passes through the coil operates the reed switch contacts disc speed capacitor... 1/4 watt, and c-c, will allow the reed switch is 'normally open ' type continue to this! Be completely separate from the magnet 's field pattern curve activate and deactivate at particular! … how to make simple reed switch Terms Glossary a new package may range. The basic working of a pair of flattened ferromagnetic strips ( reeds ) which are sealed... Both these devices produce a magnetic field which attracts a lever and changes the switch planes!