[Instructions from Anders Hørtvedt] [Instructions from Thomas Winterfeldt]
From: Anders Hørtvedt <email@example.com>
Date: Thu, 30 Jan 1997 18:08:22 +0100
To: Sidecar News Group <SIDECAR@valiant.CDS.TEK.COM>
Subject: RE: Heated visor, I try to explain how (quite long and detailed)
Regarding the description of heated visors, I feel a little bit uncertain on how to describe it, but I'll give it a shot:
What I have done, is to take a normal visor, preferrably of the scratch resistant variant, (since they usually last longer) and drill a series of small holes in the upper and lower region of the visor, approx 10 mm apart, and each row of holes approx 50 mm apart, or whatever might be suitable.
A little ASCII drawing here:
Visor:----> ___________________________________ |. . . . . . . . . . . . . . . . . .| | | | | | | |. . . . . . . . . . . . . . . . . .| |___________________________________|Then you ride your rig to an electrical store and buy some resistance wire. I don't know what the correct english term for this wire is, but it is a kind of thin metal wire with pretty high electrical resistance. The point is that this wire will go red hot when a suitable current is passed thru it.
The wire must be passed thru the holes, in a way that makes most of the wire stay on the inside of the visor
Visor:----> __________________________________ |. . ._. . _. . . . . . . . . . . .| | | | | | | | | | | | | | | | | | | | | | |_|. |_|. . . . . . . . . . . . .| |__________________________________|You get the point?
or in a zig-zag pattern, outside and inside every other time like this:
Visor:----> ___________________________________ |. . . . . . . . . . . . . . . . . .| | \ /\ | | \ / \ | | \ / \ / | |. . \/. . . \/. . . . . . . . . . .| |___________________________________|And so on...
What you prefer, is mostly a personal question. In my experience, most of the ice bulds up on the inside of the visor, and since visors tend to lead heat quite badly, my preferred solution is the first, where all the vertical wires are on the inside, when all the horizontal (shorter) wires ar on the outside.
When the visor is drilled, and the wire is passed thru the holes, you end up with one end of the resistance wire on each side of the visor.
Connect each end of the wire to a softer two-lead wire of proper thickness, e.g. 2x1mm2. This wire should be connected to the bike's 12Volt supply trough a fuse, switch and plug. Personally, I have used a standard 6.3 mm Jack plug, the same type as my son uses on his electric guitar. The reason for selecting this type of plug, is that it will release from the female plug quite easily in the event where I leave the bike in a hurry. For the same reason, I have the female plug hanging from the end of a 20 cm long wire, not a chassis plug in a hole in the fairing or other panel. The reasoning is that if I ever hit something hard and were thrown off, I'd rather have plug leave the female plug, instead of me getting my neck hurt.
One question remains: what resistance should the wire have? In my experience, a place between 10 and 30W is sufficient (or rather: if you heat more, your visor will melt). For 12V that should mean some place betwen 6-12 ohms on the total length of wire.
A heated visor does not heat your face, but it meens that you may ride with the visor closed, even when it is cold. If you don't have any heat, the visor will ice on the inside if you keep it closed below -15 C in my experience.
This is the poor-mans solution, I'm aware that there are several helmets that may be supplied with heated visors from the factory.
Of course, if you have plenty of electrical supply on your rig, the next step is to use more of the same wire to make heated grips, heated soles to put in the boots..... The list goes on.
I hope that I made a understandable explanation? If some of you need more info, I'll try to help.
Anders Hørtvedt, N-3640 Skollenborg, Norway
I have built a heated visor myself. You need some resistive wire. The power put into the visor to work properly should be around 20 Watts.
Take your visor off your helmet. Lay it on flat ground and put a piece of paper on top. Mark the visor's outline on the paper then mark the width inside this outline you want to have clear. Draw a line 1 cm from the top, a second one 2 cm from the top, and a third one 1 cm from the bottom of the visor. Go and mark points on these lines with 1 cm distance to each other.
Now imagine these points being holes and putting a wire through each starting at the top. The first hole being plugged is on either side in the second line from top. Run the wire from top to bottom on the inside and from left to right (or right to left, depends where you started) on the outside. Once you have reached the other end run the wire back to where it started using the first line of holes from the top.
Now that you have an idea of how the wire is laid out, calculate the amount of wire you will use. You can calculate what type of wire you need by some very simple formulas. Let's assume you end up with 2 meters of wire :
So we know now we have to get 1.6 Amperes of current through the wire in order to produce 20 Watts of heat.
Now we know the complete length of wire should have a resistance of 7.5 Ohms. This wire is sold as Ohms/Meter which means we will need 2 Meters of a wire that has 3.75 Ohms/Meter (or anything close to that value). I do not know where to get such wire in the UK (in the US I would recommend Radio Shack, in Germany it would be either Conrad or Voelkner). A good connector is this type of cinch connection used in stereos. If it all gets to hot I can give you an URL that describes a very simple circuit to regulate heated grips which can be used for heated visors too.
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