Both - in normal use they will be what they are, brake, tail, indicator, reverse - but when the magic switch is flipped a pretty pattern. Either way, for a retro fit LED the circuit will have to assume the same current draw as a normal bulb - how that works out for original equipment LEDs is another matter

Well that slightly complicates things... my circuit uses "low-side" drivers, meaning the loads are fed with +Ve volts, and the switch to ground is on the board. What you are going to need is "high-side" drivers, giving volts to the loads that are connected to ground. Having that working as an alternative to the vehicle electrics using a "magic switch" will be a challenge. I need to give it some thought .....

 

This should help tracing out the circuit.
The reference designators are applied as if done by PCB software, so they won't match your schematic.

 

Are these lights going to be turned on and off by the car's electrics ?

No, but they will be joined to the car's circuit. The ECU point being you can't just swap out existing bulbs for LED without adding a resistor, so the load will be the same.

 

Well that slightly complicates things... my circuit uses "low-side" drivers

This one uses old-school Darlington transistors.

 

This should help tracing out the circuit.

Thank you - that is very helpful. With a factory-made PCB it's easy to trace out the circuit, but I am having to meter out every connection just to check.

 

The reference designators are applied as if done by PCB software, so they won't match your schematic.

This is what I originally came up with - some of the footprints are way off and need to be edited, but is it close?

 

If you post your kicad file, I'll unscramble it for you.

 

Running the schematic in the SPICE simulator produces the warnings below. There were a host of errors, mostly resistors the wrong way round and other issues that changing resistor values appeared to resolve. Not really sure about these warnings though. Any ideas?

Note: Starting dynamic gmin stepping
Trying gmin = 1.0000E-03 Note: One successful gmin step
Trying gmin = 1.0000E-04 Note: One successful gmin step
Trying gmin = 1.0000E-05 Note: One successful gmin step
Trying gmin = 1.0000E-06 Note: One successful gmin step
Trying gmin = 1.0000E-07 Note: One successful gmin step
Trying gmin = 1.0000E-08 Note: One successful gmin step
Trying gmin = 1.0000E-09 Note: One successful gmin step
Trying gmin = 1.0000E-10 Note: One successful gmin step
Trying gmin = 1.0000E-11 Note: One successful gmin step
Trying gmin = 1.0000E-12 Note: One successful gmin step
Trying gmin = 1.0000E-12 Note: One successful gmin step
Warning: Dynamic gmin stepping failed
Note: Starting true gmin stepping
Trying gmin = 1.0000E-03 Warning: Further gmin increment
Trying gmin = 5.6234E-03 Warning: Further gmin increment
Trying gmin = 8.6596E-03 Warning: Further gmin increment
Trying gmin = 9.6466E-03 Warning: Further gmin increment
Trying gmin = 9.9105E-03 Warning: Further gmin increment
Trying gmin = 9.9775E-03 Warning: Further gmin increment
Trying gmin = 9.9944E-03 Warning: Further gmin increment
Trying gmin = 9.9986E-03 Warning: Further gmin increment
Trying gmin = 9.9996E-03 Warning: Last gmin step failed
Warning: True gmin stepping failed
Note: Starting source stepping
Supplies reduced to 0.0000% Note: One successful source step
Supplies reduced to 0.1000% Note: One successful source step
Supplies reduced to 0.2000% Note: One successful source step
Supplies reduced to 0.3500% Note: One successful source step
Supplies reduced to 0.5750% Note: One successful source step
Supplies reduced to 0.9125% Note: One successful source step
Supplies reduced to 1.4188% Note: One successful source step
Supplies reduced to 2.1781% Note: One successful source step
Supplies reduced to 3.3172% Note: One successful source step
Supplies reduced to 5.0258% Note: One successful source step
Supplies reduced to 7.5887% Note: One successful source step
Supplies reduced to 11.4330% Note: One successful source step
Supplies reduced to 17.1995% Note: One successful source step
Supplies reduced to 25.8493% Note: One successful source step
Supplies reduced to 34.4990% Note: One successful source step
Supplies reduced to 47.4737% Note: One successful source step
Supplies reduced to 60.4483% Note: One successful source step
Supplies reduced to 73.4229% Note: One successful source step
Supplies reduced to 86.3976% Note: One successful source step
Supplies reduced to 100.0000% Note: One successful source step
Note: Source stepping completed
Initial Transient Solution
--------------------------

 

This is what I originally came up with - some of the footprints are way off and need to be edited, but is it close?

View attachment 312075



View attachment 312076

The circuit seemed to be correct but difficult to follow when wanting to understand the operation. Essentially, it was a "wiring diagram", accurate but inconvenient to read.

 

Running the schematic in the SPICE simulator produces the warnings below. There were a host of errors, mostly resistors the wrong way round and other issues that changing resistor values appeared to resolve. Not really sure about these warnings though. Any ideas?

Note: Starting dynamic gmin stepping
Trying gmin = 1.0000E-03 Note: One successful gmin step
Trying gmin = 1.0000E-04 Note: One successful gmin step
Trying gmin = 1.0000E-05 Note: One successful gmin step
Trying gmin = 1.0000E-06 Note: One successful gmin step
Trying gmin = 1.0000E-07 Note: One successful gmin step
Trying gmin = 1.0000E-08 Note: One successful gmin step
Trying gmin = 1.0000E-09 Note: One successful gmin step
Trying gmin = 1.0000E-10 Note: One successful gmin step
Trying gmin = 1.0000E-11 Note: One successful gmin step
Trying gmin = 1.0000E-12 Note: One successful gmin step
Trying gmin = 1.0000E-12 Note: One successful gmin step
Warning: Dynamic gmin stepping failed
Note: Starting true gmin stepping
Trying gmin = 1.0000E-03 Warning: Further gmin increment
Trying gmin = 5.6234E-03 Warning: Further gmin increment
Trying gmin = 8.6596E-03 Warning: Further gmin increment
Trying gmin = 9.6466E-03 Warning: Further gmin increment
Trying gmin = 9.9105E-03 Warning: Further gmin increment
Trying gmin = 9.9775E-03 Warning: Further gmin increment
Trying gmin = 9.9944E-03 Warning: Further gmin increment
Trying gmin = 9.9986E-03 Warning: Further gmin increment
Trying gmin = 9.9996E-03 Warning: Last gmin step failed
Warning: True gmin stepping failed
Note: Starting source stepping
Supplies reduced to 0.0000% Note: One successful source step
Supplies reduced to 0.1000% Note: One successful source step
Supplies reduced to 0.2000% Note: One successful source step
Supplies reduced to 0.3500% Note: One successful source step
Supplies reduced to 0.5750% Note: One successful source step
Supplies reduced to 0.9125% Note: One successful source step
Supplies reduced to 1.4188% Note: One successful source step
Supplies reduced to 2.1781% Note: One successful source step
Supplies reduced to 3.3172% Note: One successful source step
Supplies reduced to 5.0258% Note: One successful source step
Supplies reduced to 7.5887% Note: One successful source step
Supplies reduced to 11.4330% Note: One successful source step
Supplies reduced to 17.1995% Note: One successful source step
Supplies reduced to 25.8493% Note: One successful source step
Supplies reduced to 34.4990% Note: One successful source step
Supplies reduced to 47.4737% Note: One successful source step
Supplies reduced to 60.4483% Note: One successful source step
Supplies reduced to 73.4229% Note: One successful source step
Supplies reduced to 86.3976% Note: One successful source step
Supplies reduced to 100.0000% Note: One successful source step
Note: Source stepping completed
Initial Transient Solution
--------------------------

honestly….i don’t think the schematic is ready for simulation..

I’ve rearranged the schematic while maintaining the “wiring” shown on your schematic and there are still a few questions that need to be answered.

I will post soon…

 

I will post soon…

 

Hi there
The photos attached are of a board that is used for creating an effect with vehicle back lights (for instance flashing rear brake lights and rear indicators independently every half second to create an effect.)

My project is recreate this for two new units, but as a complete and utter novice need some advice. Always been quite good at repairing electronics that have failed, from food mixers to washing machines but I'm struggling to figure out what the person was doing when this was put together.

Hopefully it will spark a discussion and I can ask the right questions
View attachment 310988View attachment 310989View attachment 310990View attachment 310991

Post a photo of the wire connector so we can identify the wire color vs pin number.

 

Also, Post a good photo of the markings on the BC548 so we can match up the manufacturer to ensure the pins assignments are correct.

BTW-the PNP connections are all wrong.

 

Also, Post a good photo of the markings on the BC548 so we can match up the manufacturer to ensure the pins assignments are correct.

BTW-the PNP connections are all wrong.

OMG, I didn't even know this was a "thing", that manufacturers differed in their pin assignments, that doubles the work for PCB designers, and wiring schedules etc. Even if it's rare, it's still bad....

 

There were a host of errors, mostly resistors the wrong way round

Why would Spice consider a non-polarised device to be "the wrong way round" ?

If it does, it's daft....

 

Why would Spice consider a non-polarised device to be "the wrong way round" ?

If it does, it's daft....

It wouldn't.

 

OMG, I didn't even know this was a "thing", that manufacturers differed in their pin assignments, that doubles the work for PCB designers, and wiring schedules etc. Even if it's rare, it's still bad....

I don't know that they are different, but verification is good.

 

Why would Spice consider a non-polarised device to be "the wrong way round" ?

Got that bit of information from here.

 

Also, Post a good photo of the markings on the BC548

 

Post a photo of the wire connector so we can identify the wire color vs pin number.