> -----Original Message-----
> From: Alan B. Pearce [SMTP:A.B.Pearce@RL.AC.UK]
> Sent: Monday, February 18, 2002 5:15 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]: Switching low-voltage AC
>
> >You don't need two, the 12VAC is isolated and two won't help. The voltage
> >losses will be significant enough from just one. Why don't you use a
> >relay? No voltage loss to speak of, and at 2 operations per day, a relay
> >rated at 50,000 operations (tungsten load) should last the rest of your
> life.
> >
> >(Do be sure to get one with a suitable 'tungsten' rating, otherwise
> >there's a risk of contacts welding "on" or short life)
>
> You could always use a triac to soft start the lamp, then use relay
> contacts
> across the triac when close to 100% current. Bit complex perhaps, but
> would
> cut the losses, while being gentler on relay contacts.
>
A low value resistor with a relay accross if would be a little simpler.

But if we are going complex, how about a bridge rectifier in series with the
lamp, and a FET or bipolar on the output of the bridge rectifier.

Mike

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