Installing Relays or Solenoids(read this)

[LightningGSX]

Looking around at various articles and posts, I see everyone pretty much has the wiring of relays and solenoids down.But nearly everyone of them has a very important part of an inductive load type circuit missing...the flyback protection diode.Even most companies seem to forget about these when mechanical switches are used(and they help a lot with reliabilty).

When you energized a coil(such as the ones in relays or solenoids) current through the coil creates potential energy.When this current is switch off, this potential energy has to goes somewhere.When a mechanical (toggle or pushbutton type) or a pressure switch(such as a Hobbs) is used ,a pretty nasty arc is created across the switch contacts, which can degrade the contacts leading to failure,intermitent operation, or at least a reduced life span of the switch.Electromagnetic Radiation(EMR) is also created and can (though not likely) lead to interference of other electronics, radios, nearby sensor wires, etc.When the relays or solenoids are switched by a module of some kind, the flyback spike can fry parts inside very quickely.

The cure is a flyback protection diode.This diode will recirculate the current back through the coil and not through the circuit.They are easily obtained and very cheap(a few pennies a piece).This diode can be any common diode such as generic 1N4001 - 1N4004 rectifiers(made by several different companies and can be found at radio shack).Most companies that manufacture various control modules usually have protection installed, you should still always put external diodes on relays or solenoids.Exeptions do exist but you are not likely to encounter them.

Installing is simple.. diodes have two leads and there is a silver or white band closest to one of them.This lead should get connected to the positive side of the relay or solenoid coil and the side with no band gets connected to the negative side.Make the connection as close to the coil as possible.

This simple little part will make your circuit more reliable, plain and simple.Switches will last longer and be problem free.Hobbs switches aren't too cheap, and very annoying when they go bad.Mechanical switches are cheap, but still no less annoying when they go bad.