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# How to use a relay board – applications for electrical components

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### How to use a relay board – applications for electrical components

1. 1. How to Use a Relay Board –Applications for Electrical Components http://proto-pic.co.uk
2. 2. How to Use a Relay Board –Applications for Electrical Components A relay board is basically a printed circuit board on which thereare a number of relay switches. Before we get into applications, let’squickly define what a relay switch actually is. http://proto-pic.co.uk
3. 3. How to Use a Relay Board –Applications for Electrical Components In bare terms, a relay is simply that – a switch. It throws from onestate to another – the familiar 1 and 0 of electronics and binary code.The relay is thrown from one state to another when an electricalcurrent is passed through it, or where an electromagnetic action flipsthe switch mechanically. http://proto-pic.co.uk
4. 4. How to Use a Relay Board –Applications for Electrical Components In the latter case, which is the most common, the electromagnet ispowered by the electric current – and causes the relay switch to flip to itsalternate state.. http://proto-pic.co.uk
5. 5. How to Use a Relay Board –Applications for Electrical Components This may either turn something on or off by depending on the logic ofthe rest of the circuit will result in a positive action (like a circuit firingup) or a negative one (like a trip switch being thrown and shutting downa circuit). http://proto-pic.co.uk
6. 6. How to Use a Relay Board –Applications for Electrical Components The relay board is most commonly seen in the modern home as aconsumer unit (the thing your mum used to call a fuse board, but whichis now known as an RCD). http://proto-pic.co.uk
7. 7. How to Use a Relay Board –Applications for Electrical Components The electromagnet in an RCD unit fires when a current over a certainlevel passes through it, causing the relay switch to turn that circuit off.This prevents overload and dangerous currents being passed through thewiring in a home, and dramatically reduces the cause of electrical fires inolder properties. http://proto-pic.co.uk
8. 8. How to Use a Relay Board –Applications for Electrical Components The relay board, then, is used where a range of circuits are to becontrolled by one signal; or where you need to control a circuit inisolation from the control circuit. So you fire the control circuit, whichflips the relay switch (thereby disconnecting the control circuit) . http://proto-pic.co.uk
9. 9. How to Use a Relay Board –Applications for Electrical ComponentsThe circuit you are controlling comes to life. When that circuit has lostits current, the electromagnet controlling the relay switch lets go and itclick back to position 0, until the control circuit is fired again. http://proto-pic.co.uk
10. 10. How to Use a Relay Board –Applications for Electrical ComponentsApplications include the amplification of digital signals; and theinstallation of for example, low voltage lighting control switches. Therelay board is present between the mains power source (which has a highvoltage) and the light switch, which uses low voltage wires for insertioninto partition walls. http://proto-pic.co.uk
11. 11. How to Use a Relay Board –Applications for Electrical ComponentsThis is a fire safety and cost control measure – office partition walls arefrequently moved, so it makes no sense to hardwire them with expensivemains wiring.In many hobbyist projects, the relay board is there to act as a logic gatefor the functions of your circuits. http://proto-pic.co.uk
12. 12. How to Use a Relay Board –Applications for Electrical Components A switch is always either on or off (1 or 0) – but of course when youhave an array of switches you can quickly build complicated Booleanprocedures that allow you to do quite sophisticated things with even arelatively small number of components. http://proto-pic.co.uk
13. 13. How to Use a Relay Board –Applications for Electrical Components Normally, Boolean AND is achieved by connecting a series of normallyopen relays; while NAND and NOR are achieved when you connectnormally closed relays in specific ways. http://proto-pic.co.uk
14. 14. How to Use a Relay Board –Applications for Electrical Components Relay board components are manufactured in two states – normallyclosed, or normally open. http://proto-pic.co.uk