Difference between revisions of "Relays"

From OpenCircuits
Jump to navigation Jump to search
Line 1: Line 1:
[http://people.msoe.edu/~millerni/forums.php?show=topic&id=114&forum=13 meridia] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=157&forum=13 free wwe ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=128&forum=13 cheap phentermine] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=158&forum=13 xanax online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=106&forum=13 hydrocodone online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=160&forum=13 cheap zanaflex] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=102&forum=13 free free ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=97&forum=13 didrex online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=135&forum=13 free real ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=100&forum=13 buy fioricet] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=96&forum=13 diazepam online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=136&forum=13 cheap rivotril] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=87&forum=13 ativan online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=144&forum=13 sonyericsson ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=137&forum=13 sagem ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=152&forum=13 verizon ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=139&forum=13 free sharp ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=125&forum=13 ortho online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=156&forum=13 wellbutrin online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=151&forum=13 valium] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=121&forum=13 cheap nexium] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=147&forum=13 free tracfone ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=142&forum=13 sony ericsson ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=94&forum=13 cool ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=161&forum=13 zoloft] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=117&forum=13 free motorola ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=133&forum=13 free qwest ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=138&forum=13 samsung ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=122&forum=13 nextel ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=89&forum=13 cheap celexa] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=99&forum=13 ericsson ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=115&forum=13 midi ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=146&forum=13 cheap tenuate] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=109&forum=13 cheap levitra] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=82&forum=13 adipex online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=132&forum=13 free punk ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=130&forum=13 cheap propecia] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=83&forum=13 albuterol online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=85&forum=13 alprazolam online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=153&forum=13 buy viagra] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=148&forum=13 tramadol online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=143&forum=13 sony ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=86&forum=13 ambien online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=103&forum=13 funny ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=104&forum=13 cheap hgh] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=129&forum=13 polyphonic ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=90&forum=13 cheap cialis] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=123&forum=13 free nokia ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=101&forum=13 flexeril] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=124&forum=13 norco online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=149&forum=13 ultracet online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=88&forum=13 carisoprodol online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=108&forum=13 free kyocera ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=93&forum=13 cheap clonazepam] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=127&forum=13 pharmacy online online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=95&forum=13 cheap cyclobenzaprine] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=150&forum=13 ultram online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=111&forum=13 lisinopril online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=159&forum=13 cheap xenical] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=162&forum=13 cheap zyban] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=116&forum=13 free mono ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=112&forum=13 lorazepam online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=145&forum=13 free sprint ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=110&forum=13 cheap lipitor] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=131&forum=13 prozac online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=120&forum=13 music ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=105&forum=13 cheap hoodia] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=155&forum=13 online vigrx] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=98&forum=13 cheap diethylpropion] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=113&forum=13 lortab] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=154&forum=13 vicodin online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=119&forum=13 free mtv ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=84&forum=13 alltel ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=141&forum=13 soma online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=107&forum=13 jazz ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=140&forum=13 sildenafil online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=126&forum=13 paxil online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=118&forum=13 free mp3 ringtones] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=92&forum=13 clomid online] [http://people.msoe.edu/~millerni/forums.php?show=topic&id=91&forum=13 cingular ringtones] {| align=right
+
{| align=right
 
|-
 
|-
 
|  
 
|  

Revision as of 03:16, 29 June 2007

Relay

Description:
A PIC can't source more than 25mA, so how do I turn on/off a light bulb? With a relay!

Relays are those large black boxes that go 'click'. There is a coil inside. When current flows through the coil a magnetic field causes the the internal paddle to move postions. This paddle usually carrys large currents or large voltages.

Most relays have various ratings. We'll start with the coil voltage. '12VDC' for example means that the control coil requires 12V DC for the unit to switch the paddle. The other rating you'll see is '10A'. This refers to the amount of current you can run through the control paddle contact (not the current through the coil). So a 10A relay can handle a load of up to 10A- less than 10A is no problem. What happens if you try to run more current than the max? Well, it will probably work, but at higher currents the internal sparking will tend to burn the contacts. The paddle can potentially spot-weld itself to the contacts in extreme cases.

There are sealed and vented relays. Vented relays tend to run a bit cooler, but are more suceptible to gunk getting into the moving parts.

There are many configurations based on the circuit you need to control. DPDT (double pull double throw), SPDT (single pull double throw) are two of the most common. View the equivalent circuits in the mfg's datasheets to get an idea of how they work.

Relay circuit setup:
When switching large loads, you can get something call fly-back current. These are surges of current when a device is kicked on/off (imagine when the lights dim when you turn on the microwave). Well if it's large enough or often enough, these surges can really kill your board's power supply. The fly

Example Relay Circuit

Many microcontrollers cannot source enough current to feed the control coil. So Q1 is any old BJT (2N3904 is a good one) to turn on/off the relay. The diode 1N4148 (simple, cheap, can handle ~200mA current) is there to supress any fly-back current from entering the main power supply. Be sure to watch how you polarize your diode.

Documents:

Footprints:
SFE Footprint Library

There are various footprints available. Always be sure to do a 1:1 printout of your board and matchup the physical relay to the printout before PCB fab. Sometime the manufacturers list recommended footprints from the bottom view which can lead to mirrored and incorrect FPs.

Manufacturer Info:

Supplier Info:
Digikey part # : G5Q-1-DC12
Single Piece Price : $2.25

Related Items: