2 relays with a shared common

[john2k]

Thank you. It's quite confusing when looking online for relays because some of the same Chinese relays are expensive with some suppliers and cheap with others so price can throw you off sometimes i guess. Are there good relay brands you would recommend?

Also, lets say I have a 30A rated relay and the LED unit which the relay is powering is probably only a few amps. Will this contribute to a quicker wearing-out rate or slower? When relays fail, do they fail in NO or NC positions or can it be either?

Thank you.

 

[duke37]

Relays can vary a lot due to the requirements. Medium power relays often have silver contacts because of their high conductivity. Some relays have gold plated contacts for use on low voltage signal circuits, these should switch low voltage circuits only or the gold can be damaged and the relay reverts to a standard silver contact relay. For 12V automotive circuits I would trot down to the local scrap yard and get a relay from there. The car maker will have chosen relays which have been tested and will be reliable. (and cheap).

Relays can fail mechanicaly open or short circuit and the contacts can fail due to contamination or welding. Keep clean and do not overload.

 

[Harald Kapp]

Are there good relay brands you would recommend?

Panasonic, Tyco, Hongfa, Schrack, GE, Bosch, Omron, ...

Also, lets say I have a 30A rated relay and the LED unit which the relay is powering is probably only a few amps. Will this contribute to a quicker wearing-out rate or slower?

Slower.

When relays fail, do they fail in NO or NC positions or can it be either?

Either. Relays can fail to close the contact (e.g. when the coil wire is broken) or can fail to open the contact (e.g. when the contacts are welded from overcurrent).
If lonegvity is a concern use a

 

[Megal]

"john2k, post: 1790115, member: 25333"]Power source 2 provides powers to a 5W bulb but it fades in and fades out. I believe it does this by adjusting the voltage that eventually rises to 12V and then fading out it goes down from 12V to off position. Question is, will a regular relay work under these voltage fades? is there a particular ac market kind of relay I need? If it will work, then I am assuming the relay will only activate when voltage reaches 12V. If so is there anything I can do to make the relay be on from any voltage from 5V to 12V?

[/U]
i'm agreed with Mr. BobK, You had better to use Transistor Switch to use 5V & 12V, I oftenly do same things. There for no need worry about.
Thanks.