RE: Alarms, etc.

From: Dave_Clement-LDC009@email.mot.com
Date: Fri Apr 19 1996 - 16:42:42 EDT


From: NVOGLER@rghosp.chime.org@INTERNET on Fri, Apr 19, 1996 2:05 PM

>.... One other question, these sheet metal screws that are
>currently in my wheelwell, they're not actually grounding the system, are
>they?? I don't have to worry about shorting out the alarm if I use the
>stainless hardware, and some silicone?? Jim Mcbride had mentioned something
>about using a penny as an anode, what's the benefit / significance here??

Ned,

If you only have one wire coming from the horn then the mounting bracket/screws
are grounding the horn. Of all the places that are going to rust on your truck,
worrying about those screws should not be a priority. Put a star washer under
the head of the screw and another one between the nut and the mounting bracket
and then cover over with paint or undercoat. This will give you a good ground
connection and protect the exposed metal. If you coat everything with silicone
then put it together it will likely work then cause problems done the road with
the ground connection.

Just as a point of interest the silicone sealer you buy with the strong acetic
oder is corrosive in a high humidity environment. What you are smelling is the
acetic acid that is used as a catalyist to cure the material. Again, in the real
world not much to worry about but it will ruin circuit boards under the right
conditions.

As far as the penny is concerned in a high humidity environment where galvanic
action would errode the base metal the penny would go first saving the rest of
the surrounding metal. That is why you see zinc anodes on boats.

Dave Clement
 



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