Electrickery advise needed

Oh hold on, why not call these guys
www.carel.co.uk
I'm in the wrong time zone
An order of (say) 8 to allow for spares and 4 users.

Seems like a doddle.

 

muddy cat was thinking very hard :

An old (or new if they still sell them) open electric fire element. Put
a jubilee clip round it, with a wire to act as a tap - to adjust the
resistance to what you need.

 

Then book the ferry. I'm going to make a final decision on which one
I'm using and then post it for a week before booking. My input
regarding ferries stops there.
How much?
Shame I've got 3 different Shoei crash helmets.
They're not going to be cheap or easy to problem solve if things get
damaged.

Not as easy as wiring up your existing visor which is what I've nearly
finished doing. I'll be chucking about 18 Watts of heat through the
coil and that should comfortably remove any ice as it forms without
melting the visor.

**** knows what'll happen anywhere else but the visor will be ok.

 

All Arai road visors have a compound curve on them. You need to use the
race visors, which are specially made with a curve in one direction
only to allow the use of tear-offs.

 

Nichrome doesn't solder very well with normal solder, you might have to
use acid core solder

.... and if it were to get a bit hotter than you're after, of course, you
shouldn't anyway, for the obvious reason

best option is to crimp or trap it in-between washers

 

Wot he said.

 

Unlike you, I'll never race, but if I get a race visor instead of a
road one, I'll be faster on the road[1] *and* look cooler! Excellent...

[1] Not difficult, I know.

 

<points up there>
As I said in the first line!

I only buy the flat ones and this is because you can more easily put a fog
city or transition insert on the thing.

 

Curiously it is what I always got so didn't give it a second thought.
Possibly an RX7RR doesn't have a convex visor option.

Of course I ordered them from <braces> The Visor Shop
<thinks>
but collected in person.

 

You great shirking ****.

I'm coming over for a tinnie tomorrow night ;-)

Paul

 

Are you?

Make sure you phone first but we should be in all evening. If you want
to drink more than a sensible amount for driving home I'll put a tent
up in the garden, I think we've still got one of your tents lying
around somewhere.

 

****. Relegated to the garden ! :/

Yea, i'll give you a shout tomorrow ..

Cheers,

Paul

 

Ok, we'll let you sleep on the conservatory floor if it's raining.

Righto.

 

Its quite unlikely you'll easily get hold of a potentiometer that can handle
the current for a resistance wire visor de-icer, if you do its going to
waste an awful lot of power on any setting other than zero resistance.

The modern way of controlling current is "Pulse Width Modulation" (PWM). Its
not a black art and there are some web sites with very detailed
illustrations of how to put one together.

One of the simplest you can find is based on the LM/SE/NE555 timer chip
(multiple choice prefix letters from many manufacturers). Its literally half
a dozen components including the chip, a power MOSFET (transistor), a couple
of diodes and resistors and a potentiometer.

 

The size, weight and cost of the massive transistor + heatsink needed to
control that much current in linear mode without burning out, would far
outweigh the tiny little chip and half dozen tiny components to make a PWM
regulator that might not need any heatsink at all.

The PWM could be squeezed onto a scrap of stripboard not much bigger than an
inch square, the chip should be less than 50p and the transistor well under
£2.

The linear version would probably need several transistors in parallel (to
save the cost of a big and fucking expensive one) and would be at least as
big as a rectifier/regulator pack.

 

Crikey, 555 timers still going. I was using those to make simple
project before the sprogs and now they're old enough to buy me beer.

 

2mm square surface mount

Lol, and waste all that power as heat from the transistors? Get with it
grandad, PWM isn't hard to understand, its just switching it off and on very
fast.

 

I got a bag of em somewhere, PWM is a simple project that will fit in a
match box. Maplin even sell a little kit.
Although I would just cut the resistance wire to the correct length then it
would be fine. When I made heated grips from stainless mig wire the only
oddity I did was have a parallel to series switch so I could have 2 setting.
I also used cheep plumbers tape 'PTFE' to bind as its heat proof, so it
didn't melt my little pinky's

 

Heh, remember designing and building simple ATE rigs using those,
logic gates and LM741 op amps.

<thinks> Shit! that was 25 years ago.

 

There's various versions of CMOS types that will run to about 2MHz, very low
current and no switching spikes on the supply rail now.

The original bipolar transistor 555 is still readily available and dirt
cheap.