LED Brake Lights

[Porsche 2]

Voltage test results:
Test 1: 3.0 V LED's off.
Test 2: 2.5 V LED's off.
Test 3: 2.0 V LED's off.
test 4: 1.5 V LED's off.
Test 5: Slightly below 1.0V LED's off.
My voltmeter is analogue, pigtail was inserted into third brake light socket.

[spoke]

Excellent measurements Keith. Understood about the analogue voltmeter. You can only do generalizations of a value although your data is good.

There is one more test to finish this out and that is driving the car and checking if the CC still works. I would like to see this tested with the GND tap wire connected between resistors R2 and R3 such that 300 ohms are in series.

I'm fitting the brake boards including 3rd brake boards with 300 ohms each. With 2 brake PCBs the resultant resistance is 150 ohms. If the CC works with 300 ohm, there will be plenty of margin with 150 ohm.

Disclaimer: I'm asking you to drive your car w/o a 3rd brake light for this test. Feel free to decline to do the test as your safety will be somewhat compromised w/o a 3rd brake light.

[spoke]

Would like to determine the CC control wire input impedance.

With these measurements, the input current measured at the 3rd brake light is:

Ohms Volts Amps
100 1V .01
200 1.5V .0075
300 2V .0067
400 2.5 .00625
500 3V .006

If we assume the input impedance looking into the CC control wire is resistive to VBAT = 14V, we should be able to apply these voltages to the input and get the same current.

Assume the input resistance is 1750 ohms; current therefore is in parens():

Ohms Volts Amps
100 1V .01 (.0075)
200 1.5V .0075 (.0071)
300 2V .0067 (.0068)
400 2.5 .00625 (.0066)
500 3V .006 (.0063)

Not a bad correlation; not exact but close enough for this analysis.

[Porsche 2]

With GND wire connected between R2 and R3, CC works well!

[froggert]

Will this change have any effect on cars without cruise control?

[spoke]

Originally Posted by froggert

Will this change have any effect on cars without cruise control?

This won't affect cars w/o cruise control.

[Reiver]

Originally Posted by spoke

This won't affect cars w/o cruise control.

I take it this is for 3.2's/ '84 and up cars?

[spoke]

Originally Posted by Reiver

I take it this is for 3.2's/ '84 and up cars?

I'm told the brake housing is the same from model years 69-89. As long as the cruise control unit in whatever year is the same or similar to the unit tested, it should work fine.

[Reiver]

Originally Posted by spoke

I'm told the brake housing is the same from model years 69-89. As long as the cruise control unit in whatever year is the same or similar to the unit tested, it should work fine.

I've an '83 w CC (works) and have checked and have no brake light issue that I can see (in the dark). The 84's and up do have a different electrical system with the motronic etc...if that makes a difference.

Any other SC's out there having this light issue?

[carreradpt]

Pm to you Spoke. DT

[RocketWrench]

Spoke, I realise you are in fire right now, but did you get my PM from last week? Could you ship to the UK, or to my Dad near Seattle?

Also, could you arrange the LEDs to the customer's order?

What is your view on in-car mood lighting?

[spoke]

Originally Posted by RocketWrench

Spoke, I realise you are in fire right now, but did you get my PM from last week? Could you ship to the UK, or to my Dad near Seattle?

Also, could you arrange the LEDs to the customer's order?

What is your view on in-car mood lighting?

I did get your PM. Sorry for overlooking it. I can ship to the UK or to your dad.

Here's a couple of quotes for shipping to the UK that I got for someone else:

USPS: $30, 10 days, no tracking;
USPS: $70, 10 days, w/tracking;
UPS: $95, 5 days, w/tracking.

I can arrange LEDs for certain patterns. That is how the round brake LED came to be.
I'm trying to get the front and rear turnsignals off the ground right now so I don't have time for custom patterns at the moment.

[RocketWrench]

Originally Posted by spoke

I did get your PM. Sorry for overlooking it. I can ship to the UK or to your dad.

Here's a couple of quotes for shipping to the UK that I got for someone else:

USPS: $30, 10 days, no tracking;
USPS: $70, 10 days, w/tracking;
UPS: $95, 5 days, w/tracking.

I can arrange LEDs for certain patterns. That is how the round brake LED came to be.
I'm trying to get the front and rear turnsignals off the ground right now so I don't have time for custom patterns at the moment.

No problem - busy is good, it means its going well! Good luck...

[spoke]

Finally getting caught up with things after my daughter's wedding and the delay for the quest to find a solution compatible with the cruise control units. A pile of boards were shipped today. All boards paid for have been shipped with one exception going to Ireland while we work out shipping.

Here's a couple of pics of my car with the white LED running lights in the turnsignal bucket.



With the headlights on.

[spoke]

Making a frame to hold the 3rd brake light PCB in the inside window mounted fixture. After about 6 attempts, this frame seems to work well. Looks like something out of the new Star Wars movie.



The board and frame fit nicely.



The PCB is moved as close to the rear of the fixture as possible for the light to hit most of the lens.



The lens keeps the frame and PCB in place.

[RocketWrench]

Spoke, I'm loving your work, and I realise you might be finding suggestions tedious by now (?)....

BUT, I have two other ideas that Id like your opinion on:

1. LED brake lights in the roof vents above the rear window

2. Angel-eye LED around the inside of the headlight....

Thoughts?

[spoke]

Originally Posted by RocketWrench

Spoke, I'm loving your work, and I realise you might be finding suggestions tedious by now (?)....

Thanks, we're having fun making these.

I welcome suggestions and observations. That's why I keep posting in this thread. Lots of good ideas out there.

1. LED brake lights in the roof vents above the rear window

This would be a good place for an invisible 3rd brake light. There may be one on the market that would fit although the entire length of the vent is curved with the roof and most aftermarket LED strips are straight.

A board could be made to fit the curve then the challenge would be to find/design an enclosure.

2. Angel-eye LED around the inside of the headlight....

Not sure I'm visualizing this. The headlight on my '86 930 is a sealed beam with chrome ring. Is this for another headlight style?

[RocketWrench]

Originally Posted by spoke

Thanks, we're having fun making these.

I welcome suggestions and observations. That's why I keep posting in this thread. Lots of good ideas out there.



This would be a good place for an invisible 3rd brake light. There may be one on the market that would fit although the entire length of the vent is curved with the roof and most aftermarket LED strips are straight.

A board could be made to fit the curve then the challenge would be to find/design an enclosure.



Not sure I'm visualizing this. The headlight on my '86 930 is a sealed beam with chrome ring. Is this for another headlight style?

Regarding the roof vents, I was thinking more of individual modules per vent, that it would be possible to have one vent showing, or all of them. I even considered having yellow lights on the two ends linked to the indicators....

The angle-eye effect is a loop of LEDs inside the glass of the main headlight like this:

[Canada Kev]

You'd need to have the Euro H4s with the removable lenses to make that possible. Sugar scoops with the standard 7" sealed beams or even replacement H4s wouldn't work for that.

[RocketWrench]

Originally Posted by Canada Kev

You'd need to have the Euro H4s with the removable lenses to make that possible. Sugar scoops with the standard 7" sealed beams or even replacement H4s wouldn't work for that.

Ahhh, ok now I understand. I have the Euro H4s and have disassembled them a few times, so I imagine inserting a ring of LEDs to be reasonably simple.

But, I am no expert by any stretch and like a lot of things I think are simple, I'm often discovering different after considerable swearing..