power mosfets for switching

[Zeno]

I'm interested in making a smarter light switch for a few rooms in the
house. The switch will be controlled by a computer somewhere in the house
well away from the switch, and the smart switch module will be on a network.
What's the best way to actually turn the 115V/60Hz on and off safely and
reliably ?

I was thinking I should detect the next zero crossing and switch a relay so
as to reduce arcing on the contacts.

Can you get power mosfets in small packages that can handle like 5A through
them, operate them in an on-off switching manner, and not care about
detecting a zero crossing time ?

 

[josh lawton]

I would not waste your time switching during the zero crossing. The
load may not always have the current in phase with the voltage. I would
use a solid state relay. They can be controlled simply with 5V sigals.

Josh
Zeno wrote:

I'm interested in making a smarter light switch for a few rooms in the
house. The switch will be controlled by a computer somewhere in the house
well away from the switch, and the smart switch module will be on a network.
What's the best way to actually turn the 115V/60Hz on and off safely and
reliably ?

I was thinking I should detect the next zero crossing and switch a relay so
as to reduce arcing on the contacts.

Can you get power mosfets in small packages that can handle like 5A through
them, operate them in an on-off switching manner, and not care about
detecting a zero crossing time ?

 

[Pooh Bear]

Zeno wrote:

I'm interested in making a smarter light switch for a few rooms in the
house. The switch will be controlled by a computer somewhere in the house
well away from the switch, and the smart switch module will be on a network.
What's the best way to actually turn the 115V/60Hz on and off safely and
reliably ?

I was thinking I should detect the next zero crossing and switch a relay so
as to reduce arcing on the contacts.

Can you get power mosfets in small packages that can handle like 5A through
them, operate them in an on-off switching manner, and not care about
detecting a zero crossing time ?

SCRs are more normally used for this application.

Since you'll need safety isolation it might be simplest to use 'solid state
relays' which are a pre-packaged solution that just need a low votage low
current DC input to function.

http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=166171&Site=US&Cat=32572451

Graham