Switching AC loads with a Bridge Rectifier?

xanatos

I read in a few places that AC loads could be effectively switched with a Bridge Rectifier, as in:

"Another possibility for switching an AC load is to put it in series with the input (AC) terminals of an appropriately rated full-wave bridge." ( http://forums.parallax.com/showthread.php?67538-Switching-AC-DC-Relays-and )

While this may be an outdated method, I am very interested in this configuration and I am wondering if any of the resident gurus here might be able to point me toward a schematic that would illustrate this configuration and how it works... so far, it isn't seeming obvious to me, and I'm finding nothing of use online except vague references in passing to this.

Thanks for the info,

Dave

Leon

You can use a bridge rectifier with an SCR as an AC controller. The load goes in series with the rectifier, and the SCR goes across the output of the rectifier.

xanatos

Do you replace one of the diodes with the SCR? Still not quite sure how this works in practice...

Thanks,

Dave

Leon

The SCR goes across the output of the bridge rectifier.

kwinn

xanatos wrote: »

I read in a few places that AC loads could be effectively switched with a Bridge Rectifier, as in:

"Another possibility for switching an AC load is to put it in series with the input (AC) terminals of an appropriately rated full-wave bridge." ( http://forums.parallax.com/showthread.php?67538-Switching-AC-DC-Relays-and )

While this may be an outdated method, I am very interested in this configuration and I am wondering if any of the resident gurus here might be able to point me toward a schematic that would illustrate this configuration and how it works... so far, it isn't seeming obvious to me, and I'm finding nothing of use online except vague references in passing to this.

Thanks for the info,

Dave

The device across the +- contacts of the bridge rectifier could be a fet, bipolar transistor, SCR, or TRIAC. Of course the bridge rectifier is not needed with a TRIAC.Attachment not found.

xanatos

Thanks! I will have to play with this, for some reason I find this compellingly cool!

Dave

kwinn

xanatos wrote: »

Thanks! I will have to play with this, for some reason I find this compellingly cool!

Dave

Do be careful when playing with this, especially if you hook it up to 120VAC. The drive for the fet/bjt/scr needs to be isolated unless you are using an isolation transformer secondary as the AC source.

xanatos

Yes indeed. Actually will probably drive with an optoisolator, and the load is only 24vac. Only playing with this at the moment anyway - I just like electronics tricks like this.

Dave