I also have bought a couple of
these in the past. They are very expensive but you think about it you are protecting equipment that is worth $$$. Here's an excerpt of an old correspondence on the Gemini Yahoo Group:
Hi all
I will once again put my 1 cent into this thread.
This is a message I have sent in the past.
The Gemini 1 is sensitive to Ground loops and static electricity. Of
course lighting is also a cause of failure.
I have had to replace about 20 RS232 chips and 3 guider chips do to
either Ground loop voltage, Static electricity, or
lighting in the case of 3 of them.
I would use an isolated adapter for the Guider input, if your camera
does not have isolated outputs.
If you are using a USB to serial adapter for the RS232 input, then one
of these 2 devices will help prevent
ground loops:
http://www.keterex.com/kxusb150.php available from Mouser also.
http://www.poscope.com/product.php?pid=23
I have both and they both work. You get a message that you could have a
faster connection
if you use a USB 2.0 device with the second less inexpensive device, at
least I did.
I use them with an FTDI based USB to serial adapter from Mouser called
the US232R-10
*http://tinyurl.com/l77sez *
Tom Hilton