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Hi NCRAW
If you look at the socket on your HEQ5Pro mount ( I guess the HEQ6 will be similar) you will see a small diagram next to it which shows that the centre connection of the male socket indicated by a line ending in a dot is the positive and the outer surround of the socket indicated by a line ending in a semicircle is negative. I guess that the the term tip comes from an older type of coms switchboard plug where by the centre conductor of the plug was called the "tip" and the outer the "ring". Tip is a confusing term as sometimes it is applied to the whole multiple plugs that you have got with your power supply. In the case of the cigarette lighter end the tip is the centre conductor which is always positive on cars these days.
All this can be confusing and I would strongly recommend that if you are going to be playing around with power supplies, leads, batteries etc you should invest in a cheap electronic multimeter. I notice that JayCars have one for $7.95. This is indeed cheap for a device that can measure volts, amps, resistance (for continuity tests etc). With one of these you can then make your best guess regarding what is positive, wire it up and BEFORE you plug it into the mount put your multimeter on the 20volt scale, put the red positive lead into the centre hole in the female plug and touch the outer plug casing with the negative (black) multimeter lead (make sure you have plugged the leads into the multimeter properly in the first instance!). You should see the meter indicate about +12 volts, if you have got the lead connections to your power supply wrong the meter will show - (negative) 12 volts. If so you will need to reverse the supply leads in some way.
The suggestion of having a blocking diode in your lead means that in future
if you mix up the polarity to the lead (eg putting the crocodile clips on a battery the wrong way) then the diode will block the wrong current being
sent to your mount. A diode allows current to flow through it in one direction but not the other. A suitable blocking diode would be a type
1N5-404 (Page 103 JayCar catalogue - no I don't work for them, just have
their excellent catalogue!). This diode will cost you 25 cents. Current will flow through the diode when the banded end (cathode) of it is negative and the other end (anode) is positive. Current will not travel if the above polarities are reversed. However, a blocking diode does come with a small disadvantage as up to about 0.5 volts can be lost across it when conducting (ie instead of getting 12 volts to your mount you would get say about 11.5 volts but this should still be ok as the mount is rated for operating down to 11volts).
I hope this all helps and has not confused you further!
Cheers Peter
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