I am back again I just found a product at ON Semiconductor go here if
you want to look, I think it would do what you require. Maybe you can
rip the idea has all the design layout and stuff so see what you
think!

http://www.onsemi.com/pub/Collateral/AND8099-D.PDF

Rob


"nemo" wrote in message ...
Mike wrote in message
news:VweTb.358167$JQ1.273756@pd7tw1no...
I need to switch a very small 5vDC load with a 110vAC trigger. I wish to
keep my solution simple, and small. The 5vDC load is actually the button
contacts on a PC joystick. With my limited electronics experience, I
would
typically use a transformer to get the 110vac down to something usable
(like
12vdc). Then, I would use a 12vdc relay. While this is simple, it is not
small. Is there a single component solution, or even an IC that could do
this?? I was looking for a small (less than 1" cubed) 110vac relay but
could find nothing (my local dealer said that there isn't really an
application where 110vac is used to switch something that small, therefore
most 110vac relays will be larger to handle a larger load).
Any suggestions appreciated.
-Mike

You could use low voltage, sub-minature printed-circuit mounting relay with
a diode across the coil (they're DC) and driven by 110V through a suitable
resistor to drop the Voltage. You could easily fit all this on a 1" square
piece of Veroboard.

You'll need a bit of maths to work out the value and get the Wattage right
otherwise the resistor will get hot.

For example: using a 12V relay, measure the resistance of the relay coil and
use a resistor ten times that value. Work out the current flowing, multiply
this by the Voltage drop across the resistor, add a bit for luck and that
will give you the Wattage of the resistor you need.

A 1N4001 diode will do across the coil.

If the relay buzzes a bit, bung a 47 or a 100micro-farad electrolytic
capacitor across the coil too. Observe the polarity though or it'll go bang!

Try http://rswww.com/

They stock a good range - of everything.

Nemo