> -----Original Message-----
> From: Alan Gorham [SMTP:alan@MICROTIMA.CO.UK]
> Sent: Friday, September 26, 2003 10:55 AM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      [EE]: Options for switching ac and dc?
>
> Is there a single component that could do the following:
>
> 1) Is switched on/off by a PIC pin output,
> 2) Could drive tungsten filament bulbs from 240V ac @1A,
> 3) Could drive an array of LEDs from 18Vdc @ 1A.
>
> This is for a device that is configuarable - i.e. as you can gather from
> the
> above some users will want to have a low voltage dc output, while others
> will
> want a UK mains ac output.
>
> There are further constraints that will probably count against the obvious
> answer of a relay:
>
> The device is expected to have a lifetime in excess of 5 years and the
> switching
> device will perform a maximum of 3 million operations per year.
>
>
> I have looked at using a MOSFET in this application, but I just run into a
> brick
> wall when it comes to generating a gate voltage for the FET that will
> always be
> positive relative to the source.
>
> Alan
>
These may be usefull:

http://www.irf.com/technical-info/an937/an-937p10.htm
http://www.discovercircuits.com/PDF-FILES/fetssr.pdf

Mike




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