After driving a van around a busy UK city and taking it through many a twisty turny back road I came to appreciate this gadget no end. When we first got a van outfitted with one of this gizmo’s I recall sneering at it along with one of the other regular delivery drivers. In fact we were so put out by its incessant bleeping we stuffed a rag into its speaker to mute the damn thing we were so against it at first!

A few months after that my colleague backed it into a concrete bollard while backing into a delivery bay. The rag came out and the boss made it clear neither of us was to do that again…  So we got used to it, and never had another scrape as a result – well I didn’t anyhow.

So what is a reversing sensor? Well curiously they come in two distinct types so far. The magnetic displacement model like the one above and the sonar type like the one below.  Each has its pro’s and cons as you would expect from any bit of consumer electronics but both deliver the same thing in the end. AN audio tone is emitted that varies in pitch and or frequency as you get nearer to a solid object.

The sonar model seems to be the most common and you can easily pick out vehicles fitted with them. Just look for a set of small studs often in the rear bumper of the car. Typically there are four but this is not a fixed rule you can have 2,4,6 or any amount of these little emitters as you like. Each one when active sends out a pulse that when reflected off an object triggers the buzzer to warn you that your getting nearer to something. The power requirement is low and they can usually run off the same circuit that you reversing lights do. So as you shift to reverse on come the lights and so do the reversing sensors. Retro fitting these beauties will require you (or a garage) to bore holes for them in your bumper. not really a hard task for most, but I can quite understand that some folks would be leery of cutting holes in their car themselves!

Which leads nicely onto the Magnetic Reverse parking sensor. These work by running a strip of conductive

material usually a ribbon or a self adhesive tape somewhere near the back of the vehicle so there isn’t usually any drilling needed in the bumper. The best place I have heard recommended for this is to affix the mag strip on the inside of the bumper itself. Again running off the reversing light circuit this device emits a static low level magnetic field that will “bend” if a dense or conductive object enters it.  Such distortion of the field sets off the buzzer or as in the model of sensor illustrated above buzzer and distance gage display.  As human bodies

have a small electric current running through them I guess we set off the field just as well as a concrete pillar with re-bar in it does! Range of these devices may well be a bit lessthan that of the sonar types but they seem to manage well enough out to three to five feet. Also unlike the ultrasonic devices they can’t be fooled by light weight barriers like bushes and wire fences that still might scratch your paint.

I particularly like these because their from the UK as well….