Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading up.
Later Mercs have got LED lighting which does fade in and out OK - but it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to modify it.

--
*To be intoxicated is to feel sophisticated, but not be able to say it.

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

On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading up.
Later Mercs have got LED lighting which does fade in and out OK - but it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to modify it.


Why don't you replace the traic ;-)

On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading up.
Later Mercs have got LED lighting which does fade in and out OK - but it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to modify it.

Probably. I can't imagine it being worth doing. Tungstens have zero output at near half power, LEDs have zero output near zero power, hence the behaviour you see.


NT

This sounds like a simple circuit charging up a capacitor to bias on a
transistor. The problem probably is that the settings used assume a lower
resistance load than the led. It depends if its using someform of feedback
to achieve the more smooth gradual illumination.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Dave Plowman (News)" wrote in message
...
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading up.
Later Mercs have got LED lighting which does fade in and out OK - but it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to modify
it.

--
*To be intoxicated is to feel sophisticated, but not be able to say it.

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

In article ,
whisky-dave wrote:
On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in
and fade out when switched on and off. On a Merc. Owner wanted some
slightly brighter lights so changed from tungsten to LED. The auto
system still does a graceful fade out - but sort of leaps to on, rather
than fading up. Later Mercs have got LED lighting which does fade in
and out OK - but it's not just a case of changing the module which on
the later cars is part of other things too.

On this model the module is stand alone, so would be possible to modify
it.


Why don't you replace the traic ;-)

'cos car electrics are dc

--
from KT24 in Surrey, England

On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:

Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in
and fade out when switched on and off. On a Merc. Owner wanted some
slightly brighter lights so changed from tungsten to LED. The auto
system still does a graceful fade out - but sort of leaps to on, rather
than fading up. Later Mercs have got LED lighting which does fade in
and out OK - but it's not just a case of changing the module which on
the later cars is part of other things too.

On this model the module is stand alone, so would be possible to modify
it.


Why don't you replace the traic ;-)

'cos car electrics are dc

Except for Ford model T.


NT

wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics were
DC and not AC?

On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.


--
Truth welcomes investigation because truth knows investigation will lead
to converts. It is deception that uses all the other techniques.

In article ,
wrote:
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
In article ,
whisky-dave wrote:
On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News)
wrote:

Asking here in the hope someone has come across this and may have
an answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade
in and fade out when switched on and off. On a Merc. Owner wanted
some slightly brighter lights so changed from tungsten to LED. The
auto system still does a graceful fade out - but sort of leaps to
on, rather than fading up. Later Mercs have got LED lighting which
does fade in and out OK - but it's not just a case of changing the
module which on the later cars is part of other things too.

On this model the module is stand alone, so would be possible to
modify it.


Why don't you replace the traic ;-)

'cos car electrics are dc

Except for Ford model T.

not very relevant in the contexct of a Merc's interior lights.

--
from KT24 in Surrey, England

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

--
from KT24 in Surrey, England

On Thursday, 17 November 2016 19:06:31 UTC, charles wrote:
In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:
tabbypurr wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

Quite so. The Ford T had nothing powered by the battery bar the trembler coil, and its ac system was unable to charge the battery. In fairness with no electric starter, and no load bar briefly the trembler coils at start time, it didn't need much charging, so plugging it in on occasion was workable.


NT

"charles" wrote in message
...
In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

True, although early cars had no starter motor (and therefore needed no
battery). Were there any other pre-starter-motor cars that had AC electrics?

charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

--

Roger Hayter

Brian Gaff wrote:

This sounds like a simple circuit charging up a capacitor to bias on a
transistor. The problem probably is that the settings used assume a lower
resistance load than the led. It depends if its using someform of feedback
to achieve the more smooth gradual illumination.
Brian

Nowadays such things are more often done with a microprocessor. It is
probably actually cheaper than the high value stable capacitor you would
need tor the analogue timer. My bathroom fan does its timer this way,
making modifying its behaviour a work in progress.


--

Roger Hayter

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto


--
"Socialist governments traditionally do make a financial mess. They
always run out of other people's money. It's quite a characteristic of them"

Margaret Thatcher

"Roger Hayter" wrote in message
...
charles wrote:
to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

On cars that used a magneto and which therefore generated alternating
current at HT voltage, was the phase of the magneto "hard-wired" to that of
the crankshaft (eg by gear/chain/toothed belt drive), so each pulse of the
magneto corresponded to the instant when a spark was required in one of the
cylinders, or was it totally asynchronous, with it being a matter of luck
whether the magneto was outputting maximum voltage at the instant when a
spark was required? Or did they rectify the magneto output and smooth it
slightly with a capacitor to keep the HT at a high voltage irrespective of
the phase of the magneto?

The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually wasn't.

--

Roger Hayter

On Thursday, 17 November 2016 19:40:17 UTC, Roger Hayter wrote:
charles wrote:
In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:
tabbypurr wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:

'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

The T was handle start, carbide lights, magneto ignition & no electrical accessories. But it still needed a battery, the magneto couldn't generate a spark at crankhandle speed.

Start sequence:
Switch to trembler coil ignition
Crank
Switch to magneto ignition
- Or shout for assistance if it just ran you over.


NT

On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is debatable.


--
You can get much farther with a kind word and a gun than you can with a
kind word alone.

Al Capone

On Thursday, 17 November 2016 19:59:45 UTC, NY wrote:
"Roger Hayter" wrote in message
...
charles wrote:

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

On cars that used a magneto and which therefore generated alternating
current at HT voltage, was the phase of the magneto "hard-wired" to that of
the crankshaft (eg by gear/chain/toothed belt drive), so each pulse of the
magneto corresponded to the instant when a spark was required in one of the
cylinders, or was it totally asynchronous, with it being a matter of luck
whether the magneto was outputting maximum voltage at the instant when a
spark was required? Or did they rectify the magneto output and smooth it
slightly with a capacitor to keep the HT at a high voltage irrespective of
the phase of the magneto?

Magnetos have the magnet in the edge of the engine flywheel, producing one timed spark per rev.

Trembler coil ignition ran all the time, resulting in very ropey spark timing & rough running. Hence it was just used for starting.


NT

On Thursday, 17 November 2016 20:32:04 UTC, The Natural Philosopher wrote:
On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:
On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:
In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:
tabbypurr wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:

'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is debatable.

Theoretically ac could have been connected to a stepup transformer for long enough to ensure a spark happened. But an LT sliding metal contact timing switch would have worn, oxidised & pitted badly. IIRC reliable distributors came later.


NT

On Thu, 17 Nov 2016 12:33:17 -0800 (PST), wrote:


On cars that used a magneto and which therefore generated alternating
current at HT voltage, was the phase of the magneto "hard-wired" to that of
the crankshaft (eg by gear/chain/toothed belt drive), so each pulse of the
magneto corresponded to the instant when a spark was required in one of the
cylinders, or was it totally asynchronous, with it being a matter of luck
whether the magneto was outputting maximum voltage at the instant when a
spark was required? Or did they rectify the magneto output and smooth it
slightly with a capacitor to keep the HT at a high voltage irrespective of
the phase of the magneto?

Magnetos have the magnet in the edge of the engine flywheel, producing one timed spark per rev.

Not on our Fordson N type tractor , Separate unit just driven from
the engine.

Trembler coil ignition ran all the time, resulting in very ropey spark timing & rough running. Hence it was just used for starting.

Not a coil in sight.

It's nearly 50 years ago but on starting which unless you were built
like Charles Atlas was done by winding the starting handle one
cylinder movement at a time the magneto had a spring mechanism which
wound up and the flipped the rotor fast enough to create the spark.
Once the engine fired this was mechanism was disengaged and the rotor
run directly. Heck easier to read the Manual
http://www.sky-net.org.uk/kelvin/tec...as/rf4_manual/


Could get a good spark just by turning the end of an unmounted unit by
hand, Dad did not appreciate this when we connected the output to a
wire taped very carefully to the seat of the outside loo where just a
couple of strands poked above unseen.

G.Harman

NY wrote
wrote
charles wrote

'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic
car electrics were DC and not AC?

Yes, the battery. No way of powering
the lights with the engine not running.

On Thursday, 17 November 2016 22:45:49 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote
charles wrote

'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic
car electrics were DC and not AC?

Yes, the battery. No way of powering
the lights with the engine not running.

early cars had acetylene lights.


NT

wrote in message
...
On Thursday, 17 November 2016 22:45:49 UTC, Rod Speed wrote:
NY wrote
tabbypurr wrote
charles wrote

'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic
car electrics were DC and not AC?

Yes, the battery. No way of powering
the lights with the engine not running.

early cars had acetylene lights.

He was asking about pre-electronic car electrics.

The Natural Philosopher wrote:

On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is debatable.

You just use a high enough frequency.

--

Roger Hayter

In article ,
wrote:
On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in
and fade out when switched on and off. On a Merc. Owner wanted some
slightly brighter lights so changed from tungsten to LED. The auto
system still does a graceful fade out - but sort of leaps to on,
rather than fading up. Later Mercs have got LED lighting which does
fade in and out OK - but it's not just a case of changing the module
which on the later cars is part of other things too.

On this model the module is stand alone, so would be possible to
modify it.

Probably. I can't imagine it being worth doing.

Not up to you - or me, come to that. It's something the owner wants.

Tungstens have zero output at near half power, LEDs have zero output
near zero power, hence the behaviour you see.

Did you miss the bit where newer cars manage it with LEDs?

--
*Sleep with a photographer and watch things develop

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

In article ,
charles wrote:
Why don't you replace the traic ;-)

'cos car electrics are dc

Doubt our Dave knows the difference between a triac and SCR. ;-)

--
*You're just jealous because the voices only talk to me *

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

In article ,
Roger Hayter wrote:
Brian Gaff wrote:

This sounds like a simple circuit charging up a capacitor to bias on a
transistor. The problem probably is that the settings used assume a
lower resistance load than the led. It depends if its using someform
of feedback to achieve the more smooth gradual illumination.
Brian

Nowadays such things are more often done with a microprocessor. It is
probably actually cheaper than the high value stable capacitor you would
need tor the analogue timer. My bathroom fan does its timer this way,
making modifying its behaviour a work in progress.

Could well be. Have looked to see if there are any dedicated chips for
this job - but so far no luck.

--
*If we weren't meant to eat animals, why are they made of meat?

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

On Friday, 18 November 2016 00:21:33 UTC, Dave Plowman (News) wrote:
In article ,
tabbypurr wrote:
On Thursday, 17 November 2016 15:24:55 UTC, Dave Plowman (News) wrote:

Car interior lights have an auto 'dimmer'. They do a graceful fade in
and fade out when switched on and off. On a Merc. Owner wanted some
slightly brighter lights so changed from tungsten to LED. The auto
system still does a graceful fade out - but sort of leaps to on,
rather than fading up. Later Mercs have got LED lighting which does
fade in and out OK - but it's not just a case of changing the module
which on the later cars is part of other things too.

On this model the module is stand alone, so would be possible to
modify it.

Probably. I can't imagine it being worth doing.

Not up to you - or me, come to that. It's something the owner wants.

Tungstens have zero output at near half power, LEDs have zero output
near zero power, hence the behaviour you see.

Did you miss the bit where newer cars manage it with LEDs?

No. At the risk of stating the obvious if an analogue fade circuit starts & stops at half power there's a good chance it can be modded by changing a set point.

There isn't really any useful answer to your question unless you can find a stand alone retrofit module or you post the schematic.


NT

On 17/11/16 23:48, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly a DC
device.

They need not rely on a battery. If, for example, you have a starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is debatable.

You just use a high enough frequency.


Which the technology of the day wouldn't have been able to generate.

A magneto is AC at crank speed synched to the crank, if that's what you
want to see it as. But its not AC as we understand it today.

And magnetos still had contacts for timing the spark.


My point being that the magneto was at the a time a well used fairly
cheap reliable and well understood beast, and there was no point in
doing it differently until cars came with batteries, and dynamos, which
introduced a whole new level of sophistication. The electric starter,
the electric lights - and the magneto disappeared leaving behind only a
coil, contact breaker and eventually a distributor. And that didn't
really change till the advent of electronic ignition in the 70s.

Note that aircraft engines of WWII used magnetos too IIRC.
Reliable self contained ignition built into the engine was the magneto.

Still used in lawnmowers, and most garden power tools and most motorcycles.


--
Gun Control: The law that ensures that only criminals have guns.

On Fri, 18 Nov 2016 10:15:21 +0000, The Natural Philosopher wrote:

On 17/11/16 23:48, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car
electrics were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this
inherantly a DC device.

They need not rely on a battery. If, for example, you have a
starting handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually
wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is
debatable.

You just use a high enough frequency.


Which the technology of the day wouldn't have been able to generate.

A magneto is AC at crank speed synched to the crank, if that's what you
want to see it as. But its not AC as we understand it today.

And magnetos still had contacts for timing the spark.


My point being that the magneto was at the a time a well used fairly
cheap reliable and well understood beast, and there was no point in
doing it differently until cars came with batteries, and dynamos, which
introduced a whole new level of sophistication. The electric starter,
the electric lights - and the magneto disappeared leaving behind only a
coil, contact breaker and eventually a distributor. And that didn't
really change till the advent of electronic ignition in the 70s.

Note that aircraft engines of WWII used magnetos too IIRC.
Reliable self contained ignition built into the engine was the magneto.

Still used in lawnmowers, and most garden power tools and most
motorcycles.

And aircraft. OK, it's out of production now, but see the Cessna 152.




--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

In article ,
wrote:
Did you miss the bit where newer cars manage it with LEDs?

No. At the risk of stating the obvious if an analogue fade circuit
starts & stops at half power there's a good chance it can be modded by
changing a set point.

I don't know what the start point is. All I know is it did what looked to
be a perfect fade up and fade down with tungsten.

There isn't really any useful answer to your question unless you can
find a stand alone retrofit module or you post the schematic.

Very unlikely to find a schematic of such a proprietary part. But do have
the connections to it from the car wiring diagram.

I have slung together a lash up using a voltage reg to give a soft start
and a simple RC for the fade out. With a small tungsten, it gives a pretty
good fade in and out. With a LED, it exhibits the effect I noted. It sort
of comes on at about half brightness then fades up to full. It fades out
perfectly. Almost as if the LED had a 'strike' current.

--
*I wish the buck stopped here. I could use a few.

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

On 18/11/2016 00:24, Dave Plowman (News) wrote:
In article ,
Roger Hayter wrote:
Brian Gaff wrote:

This sounds like a simple circuit charging up a capacitor to bias on a
transistor. The problem probably is that the settings used assume a
lower resistance load than the led. It depends if its using someform
of feedback to achieve the more smooth gradual illumination.
Brian

Nowadays such things are more often done with a microprocessor. It is
probably actually cheaper than the high value stable capacitor you would
need tor the analogue timer. My bathroom fan does its timer this way,
making modifying its behaviour a work in progress.

Could well be. Have looked to see if there are any dedicated chips for
this job - but so far no luck.


Our car has this also, had a look at the circuit board and as expected
it's just a COB. The one in ours also has canbus as well as power, so
it's at least possible the dimming is done by the BCM.

I dare say that anyone familiar with a PIC could program one up to do
the job of a basic fade in/out in a few minutes.
Anyone on here want to offer?

On 17/11/2016 15:24, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading up.
Later Mercs have got LED lighting which does fade in and out OK - but it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to modify it.


I wonder if the tungsten module is doing it by varying the voltage
whereas the LED one is PWM/current control?
Should be easy to check and then maybe knock up a voltage controlled
PWM? I note there are a few old school 555 designs for that

On 18/11/2016 11:06, Dave Plowman (News) wrote:

I have slung together a lash up using a voltage reg to give a soft start
and a simple RC for the fade out. With a small tungsten, it gives a pretty
good fade in and out. With a LED, it exhibits the effect I noted. It sort
of comes on at about half brightness then fades up to full. It fades out
perfectly. Almost as if the LED had a 'strike' current.


I still think you need to PWM it to get the effect you want, simple
voltage control is unlikely to achieve that.

On 18/11/16 12:25, Lee wrote:
On 17/11/2016 15:24, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in and
fade out when switched on and off. On a Merc. Owner wanted some slightly
brighter lights so changed from tungsten to LED. The auto system still
does a graceful fade out - but sort of leaps to on, rather than fading
up.
Later Mercs have got LED lighting which does fade in and out OK - but
it's
not just a case of changing the module which on the later cars is part of
other things too.

On this model the module is stand alone, so would be possible to
modify it.


I wonder if the tungsten module is doing it by varying the voltage
whereas the LED one is PWM/current control?
Should be easy to check and then maybe knock up a voltage controlled
PWM? I note there are a few old school 555 designs for that


I could, but I wont. Not after Plow**** claimed I had never designed
anything in my life in practice.

He's such a ****ing expert, he can do it.


--
If you tell a lie big enough and keep repeating it, people will
eventually come to believe it. The lie can be maintained only for such
time as the State can shield the people from the political, economic
and/or military consequences of the lie. It thus becomes vitally
important for the State to use all of its powers to repress dissent, for
the truth is the mortal enemy of the lie, and thus by extension, the
truth is the greatest enemy of the State.

Joseph Goebbels

On 18/11/16 12:29, Lee wrote:
On 18/11/2016 11:06, Dave Plowman (News) wrote:

I have slung together a lash up using a voltage reg to give a soft start
and a simple RC for the fade out. With a small tungsten, it gives a
pretty
good fade in and out. With a LED, it exhibits the effect I noted. It sort
of comes on at about half brightness then fades up to full. It fades out
perfectly. Almost as if the LED had a 'strike' current.


I still think you need to PWM it to get the effect you want, simple
voltage control is unlikely to achieve that.

Simple current control might though.

But even that is beyond the plow****



--
A lie can travel halfway around the world while the truth is putting on
its shoes.

In article ,
Lee wrote:
On 17/11/2016 15:24, Dave Plowman (News) wrote:
Asking here in the hope someone has come across this and may have an
answer.

Car interior lights have an auto 'dimmer'. They do a graceful fade in
and fade out when switched on and off. On a Merc. Owner wanted some
slightly brighter lights so changed from tungsten to LED. The auto
system still does a graceful fade out - but sort of leaps to on,
rather than fading up. Later Mercs have got LED lighting which does
fade in and out OK - but it's not just a case of changing the module
which on the later cars is part of other things too.

On this model the module is stand alone, so would be possible to
modify it.


I wonder if the tungsten module is doing it by varying the voltage
whereas the LED one is PWM/current control?

That's a good guess, I'd say.

Should be easy to check and then maybe knock up a voltage controlled
PWM? I note there are a few old school 555 designs for that

Not seen any that do the fade in fade out when powered up and down, though.

As was said, it might be easier to use a microprocessor for this. Above my
pay grade, sadly.

--
*I wished the buck stopped here, as I could use a few*

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

"The Natural Philosopher" wrote in message
news
On 17/11/16 23:48, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 20:16, Roger Hayter wrote:
The Natural Philosopher wrote:

On 17/11/16 19:40, Roger Hayter wrote:
charles wrote:

In article ,
The Natural Philosopher wrote:
On 17/11/16 18:47, NY wrote:


wrote in message
...
On Thursday, 17 November 2016 18:28:43 UTC, charles wrote:
'cos car electrics are dc

Except for Ford model T.

Is there any fundamental reason why early pre-electronic car
electrics
were DC and not AC?

Yes.

to go further, the car electrics rely on a battery - this inherantly
a DC
device.

They need not rely on a battery. If, for example, you have a
starting
handle and carbide lamps.

You will however need a magneto

AC ignition could easily have been devised. Even if it actually
wasn't.


No, actually it couldn't.

How you gonna time a spark if your AC happens to be zero at that time?

Remember even rectifiers were hard to come by then.

The solution was the magneto. Whether you call that AC or DC is
debatable.

You just use a high enough frequency.


Which the technology of the day wouldn't have been able to generate.

A magneto is AC at crank speed synched to the crank, if that's what you
want to see it as. But its not AC as we understand it today.

And magnetos still had contacts for timing the spark.


My point being that the magneto was at the a time a well used fairly cheap
reliable and well understood beast, and there was no point in doing it
differently until cars came with batteries, and dynamos, which introduced
a whole new level of sophistication. The electric starter, the electric
lights - and the magneto disappeared leaving behind only a coil, contact
breaker and eventually a distributor. And that didn't really change till
the advent of electronic ignition in the 70s.

Note that aircraft engines of WWII used magnetos too IIRC.

Not just of WW2 either, most light aircraft still use magnetos today.

Reliable self contained ignition built into the engine was the magneto.

Still used in lawnmowers, and most garden power tools and most
motorcycles.

And light aircraft.


--
Gun Control: The law that ensures that only criminals have guns.