Mechanical Relay Guide - Revision history

Lmpacent: /* Basic Use */

2025-11-13T22:28:27Z

Basic Use

← Older revision		Revision as of 22:28, 13 November 2025
Line 20:		Line 20:

	===Basic Use===		===Basic Use===
	Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay. A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output Guide]]. A Phidget with open collector digital outputs, (such as the [{{SERVER}}/?prodid=720 REL1100] or [{{SERVER}}/?prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.		Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay.

			A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output Guide]]. A Phidget with open collector digital outputs (such as the [{{SERVER}}/?prodid=720 REL1100] or [{{SERVER}}/?prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.


	Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.		Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.

	Relays are designed to be controlled by a particular voltage applied to the coil. If you buy a relay product from us, this is taken care of for you. You will be able to switch the relays via USB with the Digital Outputs on a [[InterfaceKit Digital Outputs\|Phidget InterfaceKit]] or {{VINTHub}}. If you are integrating your own relay, you'll want to keep an eye on the specifications. The relay coil is also specified for a particular current. For example, a 5V relay might require 70mA. If you connect this relay to a very weak source of 5V, like a digital output, the output will not be able to provide 70mA, and there will not be enough current to switch the relay.		Relays are designed to be controlled by a particular voltage applied to the coil. If you buy a relay product from us, this is taken care of for you. You will be able to switch the relays via USB with the Digital Outputs on a [[InterfaceKit Digital Outputs\|Phidget InterfaceKit]] or {{VINTHub}}. If you are integrating your own relay, you'll want to keep an eye on the specifications.

			The relay coil is also specified for a particular current. For example, a 5V relay might require 70mA. If you connect this relay to a very weak source of 5V, like a digital output, the output will not be able to provide 70mA, and there will not be enough current to switch the relay.

	The load side of the relay also requires a minimum current. This minimum load current (also called "wetting current") is a requirement because the electricity needs to conduct through an oxide layer that forms on the contacts of the relay. If the minimum load current requirement of your relay is too high, you won't be able to use it to switch a signal (such as the data line on an analog sensor), you'll only be able to switch power to a circuit. If you're using a relay to switch a signal, [[#Contact Bounce\|contact bounce]] might also be a problem.		The load side of the relay also requires a minimum current. This minimum load current (also called "wetting current") is a requirement because the electricity needs to conduct through an oxide layer that forms on the contacts of the relay. If the minimum load current requirement of your relay is too high, you won't be able to use it to switch a signal (such as the data line on an analog sensor), you'll only be able to switch power to a circuit. If you're using a relay to switch a signal, [[#Contact Bounce\|contact bounce]] might also be a problem.

Lmpacent: /* How it works */

2025-11-13T22:26:08Z

How it works

← Older revision		Revision as of 22:26, 13 November 2025
Line 15:		Line 15:

	==How it works==		==How it works==
	[[File:Mechanical_relay.jpg\|thumb\|link=\|500px\|~~'''Mechanical Relay'''~~<~~br /~~>The switching arm and contacts of a mechanical relay.]]		[[File:Mechanical_relay.jpg\|thumb\|link=\|500px\|<center>The switching arm and contacts of a mechanical relay.</center>]]
	Mechanical relays use an electromagnetic coil to open or close the circuit. When current runs through the input and energizes the coil, it creates a small magnetic field which either pulls the arm of the switch away from the other contact of the switch, or pushes it down to close the switch depending on the how the switch is made. A relay also serves as an isolator, because the control (input) and load (output) ends of the relay are not electrically connected. This allows you to protect the device you're using to control the relay from power surges in your application.		Mechanical relays use an electromagnetic coil to open or close the circuit. When current runs through the input and energizes the coil, it creates a small magnetic field which either pulls the arm of the switch away from the other contact of the switch, or pushes it down to close the switch depending on the how the switch is made. A relay also serves as an isolator, because the control (input) and load (output) ends of the relay are not electrically connected. This allows you to protect the device you're using to control the relay from power surges in your application.

Lmpacent: /* Introduction */

2025-11-13T22:24:10Z

Introduction

← Older revision		Revision as of 22:24, 13 November 2025
Line 9:		Line 9:
	They perform the same function as [[Solid State Relay Guide\|Solid State Relays]], except they are less expensive and have a shorter lifespan.		They perform the same function as [[Solid State Relay Guide\|Solid State Relays]], except they are less expensive and have a shorter lifespan.
	You can use them to control [[LED Guide\|LEDs]], heaters, appliances, and generally any powered device as long as the power you're switching falls within the limits of the relay you're using.		You can use them to control [[LED Guide\|LEDs]], heaters, appliances, and generally any powered device as long as the power you're switching falls within the limits of the relay you're using.
	[[File:~~1017~~.jpg\|link=\|center\|400px]]		[[File:1014_3.jpg\|link=\|center\|400px]]


	We sell boards with multiple relays on them (such as the [{{SERVER}}/~~products.php~~?~~product_id~~=~~1017 1017~~], shown above), making it easy to control many separate circuits with your computer. Some boards, like the 1017, plug straight into your USB port, while others are designed to connect to another device, such as the digital outputs of an [[InterfaceKit Digital Outputs\|Interface Kit]] or {{VINTHub}}.		We sell boards with multiple relays on them (such as the [{{SERVER}}/?prodid=1228 PhidgetInterfaceKit 0/0/4], shown above), making it easy to control many separate circuits with your computer.


	==How it works==		==How it works==

Mparadis at 20:19, 13 July 2023

2023-07-13T20:19:03Z

← Older revision		Revision as of 20:19, 13 July 2023
Line 2:		Line 2:
	{{#seo:\|keywords=relay}}		{{#seo:\|keywords=relay}}
	[[Category:IntroGuide]]		[[Category:IntroGuide]]
	__TOC__		<div class="toclimit-3">__TOC__</div>

	==Introduction==		==Introduction==

Lmpacent at 20:01, 26 June 2023

2023-06-26T20:01:35Z

← Older revision		Revision as of 20:01, 26 June 2023
Line 1:		Line 1:
	{{#seo:\|description=Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more here.}}		{{#seo:\|description=Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more here.}}
			{{#seo:\|keywords=relay}}
	[[Category:IntroGuide]]		[[Category:IntroGuide]]
	__TOC__		__TOC__

Mparadis at 21:16, 15 June 2023

2023-06-15T21:16:19Z

← Older revision		Revision as of 21:16, 15 June 2023
Line 20:		Line 20:

	===Basic Use===		===Basic Use===
	Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay. A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output Guide]]. A Phidget with open collector digital outputs, (such as the [{{SERVER}}/?~~tier=3&catid=46&pcid=39&~~prodid=720 REL1100] or [{{SERVER}}/?~~tier=3&catid=46&pcid=39&~~prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.		Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay. A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output Guide]]. A Phidget with open collector digital outputs, (such as the [{{SERVER}}/?prodid=720 REL1100] or [{{SERVER}}/?prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.
	Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.		Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.

Mparadis at 19:37, 1 June 2023

2023-06-01T19:37:08Z

← Older revision		Revision as of 19:37, 1 June 2023
Line 6:		Line 6:
	Mechanical relays are devices that can turn on or turn off the power supplied to another device, like a switch. However, instead of having a person flip the switch, mechanical relays switch when provided with a small amount of power. This allows high-power circuits to be controlled by low-power devices.		Mechanical relays are devices that can turn on or turn off the power supplied to another device, like a switch. However, instead of having a person flip the switch, mechanical relays switch when provided with a small amount of power. This allows high-power circuits to be controlled by low-power devices.

	They perform the same function as [[Solid State Relay ~~Primer~~\|Solid State Relays]], except they are less expensive and have a shorter lifespan.		They perform the same function as [[Solid State Relay Guide\|Solid State Relays]], except they are less expensive and have a shorter lifespan.
	You can use them to control [[LED ~~Primer~~\|LEDs]], heaters, appliances, and generally any powered device as long as the power you're switching falls within the limits of the relay you're using.		You can use them to control [[LED Guide\|LEDs]], heaters, appliances, and generally any powered device as long as the power you're switching falls within the limits of the relay you're using.
	[[File:1017.jpg\|link=\|center\|400px]]		[[File:1017.jpg\|link=\|center\|400px]]

Line 20:		Line 20:

	===Basic Use===		===Basic Use===
	Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay. A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output ~~Primer~~]]. A Phidget with open collector digital outputs, (such as the [{{SERVER}}/?tier=3&catid=46&pcid=39&prodid=720 REL1100] or [{{SERVER}}/?tier=3&catid=46&pcid=39&prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.		Controlling a mechanical relay is as easy as turning on an LED or light bulb. By simply supplying enough power to energize the electromagnetic coil, you will be able to control a mechanical relay. A normal digital output will not be powerful enough without external components as described in the [[InterfaceKit Digital Outputs#Controlling a Relay with a N-Channel MOSFET\| relay section of the Digital Output Guide]]. A Phidget with open collector digital outputs, (such as the [{{SERVER}}/?tier=3&catid=46&pcid=39&prodid=720 REL1100] or [{{SERVER}}/?tier=3&catid=46&pcid=39&prodid=721 REL1101]), on the other hand, will be able to control a relay on its own.
	Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.		Relays are often used in large quantities to turn multiple devices on and off in a particular order or timing. For example, a popular trend has been to hook up many strands of Christmas lights to multiple relays and a control system in order to make them flash in rhythm with specific music.

Line 28:		Line 28:

	====Switching Speed and High-Frequency Switching====		====Switching Speed and High-Frequency Switching====
	Even though they use moving mechanical parts, mechanical relays switch very quickly. The amount of time it takes for current to begin flowing through the circuit from when the relay's input is activated is in the order of tens of milliseconds. For extremely time-sensitive applications that need to minimize switching delay, [[Solid State Relay ~~Primer~~\|Solid State Relays]] can switch as quickly as 1ms.		Even though they use moving mechanical parts, mechanical relays switch very quickly. The amount of time it takes for current to begin flowing through the circuit from when the relay's input is activated is in the order of tens of milliseconds. For extremely time-sensitive applications that need to minimize switching delay, [[Solid State Relay Guide\|Solid State Relays]] can switch as quickly as 1ms.

	You should be careful when using mechanical relays in applications that require very frequent switching. Typically, mechanical relays can only manage one contact every few seconds- any quicker and they may begin to overheat.		You should be careful when using mechanical relays in applications that require very frequent switching. Typically, mechanical relays can only manage one contact every few seconds- any quicker and they may begin to overheat.
Line 49:		Line 49:
	The major deciding factor in choosing a mechanical relay is the amount of current it's capable of switching.		The major deciding factor in choosing a mechanical relay is the amount of current it's capable of switching.
	For example, the most current you can switch with the largest mechanical relay we sell is 5A DC or 10A AC.		For example, the most current you can switch with the largest mechanical relay we sell is 5A DC or 10A AC.
	If the load you're switching consumes more current than our mechanical relays can handle, take a look at our [[Solid State Relay ~~Primer~~\|Solid State Relays]].		If the load you're switching consumes more current than our mechanical relays can handle, take a look at our [[Solid State Relay Guide\|Solid State Relays]].

	===Switch Type===		===Switch Type===
Line 76:		Line 76:
	==Troubleshooting==		==Troubleshooting==
	===Contact Bounce===		===Contact Bounce===
	As with any mechanical switch, relays are susceptible to contact bounce. This means that when the switch closes, the arm can bounce on the contact, causing the load's power to flicker slightly. This usually only matters when the application is triggered by pulses in the power signal, or for applications where meaningful data is being switched instead of power. For example, a circuit designed to increment a counter every time power is applied to its input could incorrectly interpret a bouncing relay contact as multiple switch events. Or, a circuit that uses a relay to switch an audio signal between two different paths will experience some static noise when switching if there is significant contact bounce. It's worth mentioning that [[Solid State Relay ~~Primer~~\|Solid State Relays]] don't suffer from contact bounce, because they operate without using moving mechanical parts.		As with any mechanical switch, relays are susceptible to contact bounce. This means that when the switch closes, the arm can bounce on the contact, causing the load's power to flicker slightly. This usually only matters when the application is triggered by pulses in the power signal, or for applications where meaningful data is being switched instead of power. For example, a circuit designed to increment a counter every time power is applied to its input could incorrectly interpret a bouncing relay contact as multiple switch events. Or, a circuit that uses a relay to switch an audio signal between two different paths will experience some static noise when switching if there is significant contact bounce. It's worth mentioning that [[Solid State Relay Guide\|Solid State Relays]] don't suffer from contact bounce, because they operate without using moving mechanical parts.

	===Arcing, Interference, and Sticking===		===Arcing, Interference, and Sticking===
Line 90:		Line 90:
	In order to prolong the lifespan of your relay, avoid switching loads of higher voltage or current than the relay is built for, and avoid highly inductive loads, which worsen the effects of contact arcing. Your Load will probably be inductive if it is built around a large coil of wire - motors and transformers are typical examples. A load considered resistive may also have loops of wire - for instance, hair dryers, toasters, incandescent bulbs use twisted wire elements to generate the heat. An inductive load will have thousands of loops of wire - it's a matter of scale.		In order to prolong the lifespan of your relay, avoid switching loads of higher voltage or current than the relay is built for, and avoid highly inductive loads, which worsen the effects of contact arcing. Your Load will probably be inductive if it is built around a large coil of wire - motors and transformers are typical examples. A load considered resistive may also have loops of wire - for instance, hair dryers, toasters, incandescent bulbs use twisted wire elements to generate the heat. An inductive load will have thousands of loops of wire - it's a matter of scale.

	Additionally, you should avoid switching at or near the relay's maximum frequency if possible. You can think of a mechanical relay's lifespan in terms of number times switched rather than the amount of time it's used for. A relay that doesn't need to be switched very often can last a long time. If your application requires constant switching over long periods of time, it might be more cost-effective to use a [[Solid State Relay ~~Primer~~\|Solid State Relay]].		Additionally, you should avoid switching at or near the relay's maximum frequency if possible. You can think of a mechanical relay's lifespan in terms of number times switched rather than the amount of time it's used for. A relay that doesn't need to be switched very often can last a long time. If your application requires constant switching over long periods of time, it might be more cost-effective to use a [[Solid State Relay Guide\|Solid State Relay]].

	====Arc Suppression ====		====Arc Suppression ====

Lmpacent at 16:59, 24 May 2023

2023-05-24T16:59:25Z

← Older revision		Revision as of 16:59, 24 May 2023
Line 1:		Line 1:
	~~<metadesc>~~Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more ~~at Phidgets~~.~~com.</metadesc>~~		{{#seo:\|description=Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more here.}}
	[[Category:IntroGuide]]		[[Category:IntroGuide]]
	__TOC__		__TOC__

Mparadis at 19:09, 16 May 2023

2023-05-16T19:09:30Z

← Older revision		Revision as of 19:09, 16 May 2023
Line 1:		Line 1:
	<metadesc>Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more at Phidgets.com.</metadesc>		<metadesc>Mechanical relays can switch a power or signal line by physically moving metal contacts with an electromagnet. Learn more at Phidgets.com.</metadesc>
	[[Category: ~~Primer~~]]		[[Category:IntroGuide]]
	__TOC__		__TOC__

Mparadis: Mparadis moved page Mechanical Relay Primer to Mechanical Relay Guide

2023-05-16T16:59:31Z

Mparadis moved page Mechanical Relay Primer to Mechanical Relay Guide

← Older revision	Revision as of 16:59, 16 May 2023
(No difference)