Bit O/T, but the heaters for the mirrors on both mine have failed and are
NLA - although plain glasses are still available. Anyone think of a source
for the elements only?

--
*The statement above is false

Dave Plowman London SW
To e-mail, change noise into sound.

Bit O/T, but the heaters for the mirrors on both mine have failed and are
NLA - although plain glasses are still available. Anyone think of a source
for the elements only?

Many wing mirrors are used across a range of other vehicles - sometimes
for other manufacturers... perhaps its a fairly standard bit of kit ?

(IIRC some Porsches use bog standard VW wing mirrors)

In article ,
"Dave Plowman (News)" writes:
Bit O/T, but the heaters for the mirrors on both mine have failed and are
NLA - although plain glasses are still available. Anyone think of a source
for the elements only?

Oh, what a shame. After some stoned youths came past and kicked
my wing mirror off, the heater pad was the only part still intact.
I didn't try taking all the broken glass off it though -- it was
chucked out. I did go along to the court hearings though...

--
Andrew Gabriel

In article ,
Colin Wilson wrote:
Bit O/T, but the heaters for the mirrors on both mine have failed and
are NLA - although plain glasses are still available. Anyone think of
a source for the elements only?

Many wing mirrors are used across a range of other vehicles - sometimes
for other manufacturers... perhaps its a fairly standard bit of kit ?

(IIRC some Porsches use bog standard VW wing mirrors)

It's possible, but I'd guess someone would have found this out already if
so. The option is obviously to get a vaguely similar glass and remove the
element. Checking on some prices for cars which have both, the heated ones
seem to be about 10 quid more.

--
*All those who believe in psychokinesis, raise my hand *

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
Bit O/T, but the heaters for the mirrors on both mine have failed and are
NLA - although plain glasses are still available. Anyone think of a source
for the elements only?


I am very surprised that they are NLA. Scrapyard?
You could experiment with e.g. bits of nichrome wire epoxied to that back.

In article ,
The Natural Philosopher wrote:
Bit O/T, but the heaters for the mirrors on both mine have failed and
are NLA - although plain glasses are still available. Anyone think of
a source for the elements only?


I am very surprised that they are NLA. Scrapyard?

Likely to be fooked too.

You could experiment with e.g. bits of nichrome wire epoxied to that
back.

Yes. The original is a sort of fibre pad with wide tracks on it - rather
like a PCB using something other than copper, and is just glued on. Seems
modern mirrors have the element built in like a heated rear window.

--
*Atheism is a non-prophet organization.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
"Dave Plowman (News)" writes:
Yes. The original is a sort of fibre pad with wide tracks on it - rather
like a PCB using something other than copper, and is just glued on. Seems
modern mirrors have the element built in like a heated rear window.

In a similar situation where I wanted to heat a panel, I
epoxied a chain of resistors on the back. Each one is quite
low power. You will have to be careful of water ingress and
electrolosis thought.

--
Andrew Gabriel

In article ,
Andrew Gabriel wrote:
Yes. The original is a sort of fibre pad with wide tracks on it -
rather like a PCB using something other than copper, and is just glued
on. Seems modern mirrors have the element built in like a heated rear
window.

In a similar situation where I wanted to heat a panel, I
epoxied a chain of resistors on the back. Each one is quite
low power. You will have to be careful of water ingress and
electrolosis thought.

I'm now considering using fibreglass sheet as used on PCBs with nichrome
wire in parallel runs secured by holes at either end of the run, and the
whole lot covered and secured by fibreglass resin. Any obvious problems
with this approach? I have spare glasses so can experiment.

--
*Taxation WITH representation ain't much fun, either.

Dave Plowman London SW
To e-mail, change noise into sound.

Dave Plowman (News) wrote:
In article ,
Andrew Gabriel wrote:
Yes. The original is a sort of fibre pad with wide tracks on it -
rather like a PCB using something other than copper, and is just glued
on. Seems modern mirrors have the element built in like a heated rear
window.

In a similar situation where I wanted to heat a panel, I
epoxied a chain of resistors on the back. Each one is quite
low power. You will have to be careful of water ingress and
electrolosis thought.

I'm now considering using fibreglass sheet as used on PCBs with nichrome
wire in parallel runs secured by holes at either end of the run, and the
whole lot covered and secured by fibreglass resin. Any obvious problems
with this approach? I have spare glasses so can experiment.

None, as long as you don't let the temperature get too hot.

An old acquaintance of mine was a VERY junior engineer during the
commissioning of a large fiberglass radar dish that had a petal of
nichrome inside it to de-ice it in winter..on being ordered to 'show how
the de-icer works' he duly switched it on, and, receiving no further
instructions, left it on. Only the smell of burning and the brown flower
petal shaped pattern emerging from the £100k dish eventually alerted them..

...well fortunately its polar pattern was unaffected, so they toned down
the heater voltage, repainted it and filled the cracks, and of course he
took the blame for the whole design cockup. We both left the company at
similar times. My crime had been to criticize the 'wire girl' who was
supposed to wire up prototype board for us, but who usually spent her
time knitting, and sunbathing on the roof where we tested the dishes. I
learnt after my resignation that she was the section heads mistress.

This has very little to do with car mirrors I am afraid, but it might
lighten up a dull Monday.

On Mon, 25 Sep 2006 01:23:20 +0100, "Dave Plowman (News)"
wrote:

In article ,
The Natural Philosopher wrote:
Bit O/T, but the heaters for the mirrors on both mine have failed and
are NLA - although plain glasses are still available. Anyone think of
a source for the elements only?


I am very surprised that they are NLA. Scrapyard?

Likely to be fooked too.

You could experiment with e.g. bits of nichrome wire epoxied to that
back.

Yes. The original is a sort of fibre pad with wide tracks on it - rather
like a PCB using something other than copper, and is just glued on. Seems
modern mirrors have the element built in like a heated rear window.

It can be done with copper direct onto a pcb - preferably on thin
(0.8mm) laminate.

Assume you want to raise the temperature to around 30 deg above
ambient while consuming around 2.5A Using standard tables @ 2.5A 70u
FR4 copper requires a minimum track width of around 0.7mm to avoid
exceeding thermal limits. Typical mirror heater current consumption of
2.5A @ a nominal car battery voltage means a heater element resistance
of around 5.5 ohms is required.

0.7mm copper track on 70u copper requires 16000mm of track to provide
circa 5.5 ohms. Assume a minimum 0.2mm gap between tracks. Therefore
0.9mm is needed "per track run"

Assume the mirror is 150mm wide

The mirror needs to accommodate:

16000mm/150mm = 106 tracks

106 tracks @0.9mm = 95mm minimum height - probably less than the space
that is available.

Conveniently the arrangement will fit on a standard Eurocard PCB which
could then be routed to size. Termination would probably be best with
soldered and bolted connection with bolt through lucar 0.25" tabs You
could probably knock up a layout in an hour or so with a freeware pcb
cad package. The one off cost will be about 25 quid from one of the
many online pcb manufacturers dropping to about 2 or 3 quid for 100
off quantities.

Bond the pcb copper side directly to the back of the mirror using an
appropriate adhesive. Normal slow setting epoxy would probably
suffice.


--

Matt wrote:
On Mon, 25 Sep 2006 01:23:20 +0100, "Dave Plowman (News)"
wrote:

In article ,
The Natural Philosopher wrote:
Bit O/T, but the heaters for the mirrors on both mine have failed and
are NLA - although plain glasses are still available. Anyone think of
a source for the elements only?


I am very surprised that they are NLA. Scrapyard?

Likely to be fooked too.

You could experiment with e.g. bits of nichrome wire epoxied to that
back.

Yes. The original is a sort of fibre pad with wide tracks on it - rather
like a PCB using something other than copper, and is just glued on. Seems
modern mirrors have the element built in like a heated rear window.

It can be done with copper direct onto a pcb - preferably on thin
(0.8mm) laminate.

Assume you want to raise the temperature to around 30 deg above
ambient while consuming around 2.5A Using standard tables @ 2.5A 70u
FR4 copper requires a minimum track width of around 0.7mm to avoid
exceeding thermal limits. Typical mirror heater current consumption of
2.5A @ a nominal car battery voltage means a heater element resistance
of around 5.5 ohms is required.

0.7mm copper track on 70u copper requires 16000mm of track to provide
circa 5.5 ohms. Assume a minimum 0.2mm gap between tracks. Therefore
0.9mm is needed "per track run"

Assume the mirror is 150mm wide

The mirror needs to accommodate:

16000mm/150mm = 106 tracks

106 tracks @0.9mm = 95mm minimum height - probably less than the space
that is available.

Conveniently the arrangement will fit on a standard Eurocard PCB which
could then be routed to size. Termination would probably be best with
soldered and bolted connection with bolt through lucar 0.25" tabs You
could probably knock up a layout in an hour or so with a freeware pcb
cad package. The one off cost will be about 25 quid from one of the

I thgink you'll find it's more than that when you include the
photo-plotting and other tooling costs. If you can find one that is
£25 then I'd dearly like to know.

many online pcb manufacturers dropping to about 2 or 3 quid for 100
off quantities.

Bond the pcb copper side directly to the back of the mirror using an
appropriate adhesive. Normal slow setting epoxy would probably
suffice.

I would use a piece of thermally conductive pad such as silpad but it
ain't cheap (Farnell sell it).

MBQ

On 25 Sep 2006 07:35:19 -0700, wrote:

Matt wrote:
The one off cost will be about 25 quid from one of the

I thgink you'll find it's more than that when you include the
photo-plotting and other tooling costs. If you can find one that is
£25 then I'd dearly like to know.

It's been a while since I knocked some pcbs up and my "local" supplier
plus an alternative have since gone to the wall. pcbpool.com who I've
used a few times in the recent past are 39 euros on 8 day delivery for
single sided eurocards including vat and tooling - 39 euros = 26 quid
Postage is a couple of quid extra though.

Doublesided one off price is 49 Euros = 33 quid

Bond the pcb copper side directly to the back of the mirror using an
appropriate adhesive. Normal slow setting epoxy would probably
suffice.

I would use a piece of thermally conductive pad such as silpad but it
ain't cheap (Farnell sell it).

I remember buying some about 10 years ago rather than using messy heat
sink compound on a processor heatsink. A piece slightly larger than
the size of an A4 sheet of paper was about 15 quid which I though a
bit expensive then - i just checked and it's now 43 quid for a 300mm x
300mm sheet! The problem with using this in the heated mirror
application is it needs to be clamped which might not be too easy to
achieve. I reckon an epoxy adhesive would work much better.

--