Light flashing unit for car

Thread Starter

gchq

Joined Dec 27, 2023
69
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 :)
CB_01.pngCB_02.pngCB_03.pngCB_04.png
 

Ya’akov

Joined Jan 27, 2019
9,170
Welcome to AAC.

The device is pretty simple.

It’s using a 5V regulator to get power for the electronics.
It was once fused but someone “cleverly“ bypassed that “unnecessary“ feature.
It uses a 555 timer for… timing, so several of the passive components will be in support of that chip.
It uses three Darlington pair power transistors (very old school, you’ll probably want MOSFETs now)
and that’s about it.

But, your task is going to be to carefully trace the circuit on the PCB and create a schematic. Being a single-sided PCB it will be relatively easy. I realize this is probably a stretch for you, but I‘m confident you can manage it.

You will need to get parts numbers off the transistors, and decode the resistor color codes. It will probably take a few revisions to convert an initial rat’s nest of connections into something readable. As you work, you can ask about component ID, symbols to use, and the like.

WIth the schematic in hand, you can move on to the next step of designing a modern version based on this one. Or, you can carefully describe the except behavior of this one and have a go at designing a modern version that provides the functionality.

Frankly, with a cheap and cheerful MCU (Microcontroller Unit), something Arduino compatible, for the same amount of effort as tracing the PCB and recreating the board you could have a far more capable device, with fewer components, that can be revised with code changes not needing a new PCB. It could be flexible in how it controls the light, expandable (add “channels” trivially), and would give you a chance to add new skills that would open up unlimited opportunities for other projects.

How you proceed is up to you, I would suggest first writing a clear, concise, and complete description of exactly what the board did. This will be useful no matter what path you select.

Good luck, ask any questions you have.
 

Thread Starter

gchq

Joined Dec 27, 2023
69
Hi Ya’akov

Thank you for your reply. Upgrading to something better will be a lot more useful. The MJ2501 Darlington Transistors are out of production, although some suppliers still have a few in stock.

Reading the 'AH694' on the side of the PCB made me think it was repurposed from an old Philips 22AH694 tuner made in the eighties.

As I have never seen the result of the existing board it is more challenging to create something similar. I did notice the fuse - but was told that an inline fuse from the car's positive (switched) was used instead. Basically, from what I have been told, the pos and neg are connected with pos outlets attached to indicators, brake lights and such like to display a pattern when switched on. The brake lights must be on the same circuit so they would flash together, and the indicators could flash independently.

I did think the same could be achieved with just some heavy-duty flasher units, but the effect needs to be a lot faster.

MCU seems to be the way to go, and the fact that it is programmable would be an advantage (I write business application software so that should not be too difficult).

If you have any suggestions as to what I am looking for with an MCU it would be very helpful until the proverbial drops.

Thanks again for the reply :)
 

Ya’akov

Joined Jan 27, 2019
9,170
Hi Ya’akov

Thank you for your reply. Upgrading to something better will be a lot more useful. The MJ2501 Darlington Transistors are out of production, although some suppliers still have a few in stock.

Reading the 'AH694' on the side of the PCB made me think it was repurposed from an old Philips 22AH694 tuner made in the eighties.

As I have never seen the result of the existing board it is more challenging to create something similar. I did notice the fuse - but was told that an inline fuse from the car's positive (switched) was used instead. Basically, from what I have been told, the pos and neg are connected with pos outlets attached to indicators, brake lights and such like to display a pattern when switched on. The brake lights must be on the same circuit so they would flash together, and the indicators could flash independently.

I did think the same could be achieved with just some heavy-duty flasher units, but the effect needs to be a lot faster.

MCU seems to be the way to go, and the fact that it is programmable would be an advantage (I write business application software so that should not be too difficult).

If you have any suggestions as to what I am looking for with an MCU it would be very helpful until the proverbial drops.

Thanks again for the reply :)
Happy to help.

I am glad you are open to the MCU route. It is the “right way” to do things at this point, offering a lot of flexibility and simplicity in terms of the circuitry buy pushing off the messy bits to code.

As far as a recommendation for a particular MCU/dev board—there is an embarrassment of riches problem. If you haven’t used the Arduino platform before, I would suggest starting with that. What I mean is, get a starter kit and familiarize yourself with the parts and process.

Making a few small learning projects, and modifying them to do new things you think of, will set you up for a much smoother transition to real applications. The board you use for learning is not likely to be the best choice for your application—but they are very inexpensive and if you get an Arduino-designed board to start the friction of getting rolling with it will be greatly reduced.

Briefly, because there is so much confusion, let’s work out what an “Arduino” is. You will hear things like “I used an Arduino to do X”. This is fine for informal speech but it leads to great confusion when practical work needs doing. Here’s the key points:

  • Arduino is first and foremost an ecosystem that includes a variety of APIs to support various processor architectures and describe development boards (e.g.: pin definitions, programming requirements, &c.) This allows a great range of chips and boards to be programmed in a simple, messy details hidden, IDE which is part of the ecosystem. (If you are a VS Code user, there is also Platform.IO which is an Arduino-compatible environment for VS Code. It has both advantages and disadvantages over the official IDE)

  • The Arduino IDE is a reasonably good IDE offering the necessary features to write programs, upload code to the MCUs, and debug. It uses a variant of C++, close enough to the language to make a C++ programmer quickly capable of using it. Simplifications make the neophyte C++ programmer able to learn pretty easily.

  • Arduino is an organization that produces the official parts of the Arduino environment, though there is a great deal of contribution in terms of libraries, cores (processor support files), and board definitions. Some comes from manufacturers, some from the community. The result is a rich collection of possibilities for MCU deployment.

  • Arduino designs development boards, so there are some boards that can reasonably called “Arduinos”. But at this point, popular as the Arduino-designed and manufactured boards, and there clones (it is all open source), are there are so many other choices there is no reason to assume an “Arduino” is what you want or need. I use them, but as exceptions rather than the rule.

So, ”I used an Ardunio“ may be right, but usually not. And, you are unlikely to “use an Arduino” for this project, though you are very likely to use the Arduino environment. But to get started, “using an Arduino“ makes some sense—that is, using an Arduino-designed board which will have the most tutorial and reference content, and direct support from a vanilla installation of the environment.

(The links below are from Amazon US, usually Amazon UK has the same products but if not, you can use them as a guide and ask about ambiguities of other possibilities.)

That said, I would recommend a starter kit like this one. But let me quickly add this one is pricey—for a reason. This is the official Arduino starter kit. It features the ubiquitous Arduino R3 development board, and a bunch of passives and sensors, as well as a breadboard. The reason I recommend this one is that the sale will benefit the Arduino organization that drives this whole thing, and that produces the Arduino IDE. If you can afford it, it is making a donation to support the work and getting the kit you need to get started.

Alternatively, you can find other options like this Elegoo kit for about half the price. I have purchased these as gifts for people wanting to learn, and they are fine. It’s not identical to the Arduino version but has plenty of tutorial content and parts to do. lot of things.

Even cheaper kits with fewer components are available and would “work” to get you started, but while this Elegoo kit at about half of the other one is OK, I would recommend the previous one.

As far as the flasher board, there are two manufacturers of MCUs popular in the Arduinoverse I generally (but not exclusively) default to: ESPRESSIF with their ESP series and Mircrochip and the AVR processors. ESPRESSIF is focused on amazing SoC (System on a Chip) products with wireless technologies on board (Wi-Fi, BT, &c.) while Microchip has simple, robust, and very inexpensive options like the 8-pin ATTiny85 that, once programmed, only needs two additional passive components in addition to the chip to be fully functional.

So, I would say: get a kit and have fun learning this stuff. It will put you in a much better position for success and help you understand design choices.
 

Thread Starter

gchq

Joined Dec 27, 2023
69
Thanks again for your prompt response.

I have just checked out the Arduino IDE for VS 2022 and I guess that would be the way to go. Never been a fan of C++, or even C# preferring VB.net, although anything web based now needs a lot of jQuery which is kinda similar. It looks like all their templates are C++ and, unless I misread something, they say 'free trial' but no indication of the cost after that.

Will hop over to their site and have a read in depth.
 

Ya’akov

Joined Jan 27, 2019
9,170
Thanks again for your prompt response.

I have just checked out the Arduino IDE for VS 2022 and I guess that would be the way to go. Never been a fan of C++, or even C# preferring VB.net, although anything web based now needs a lot of jQuery which is kinda similar. It looks like all their templates are C++ and, unless I misread something, they say 'free trial' but no indication of the cost after that.

Will hop over to their site and have a read in depth.
Platfom.IO on VS Code is completely free. You might want to look at that.’

As for as C++ goes, it’s not my favorite either but in this context it’s not terrible.

You can also program a lot of the MCUs in MicroPython, which has its own environment and is fairly popular. I don’t have a lot of information about it because I don’t use it, but Arduino do offer an “experimental” MicroPython environment with a code editor for their boards as one option for trying it.

I don’t otherwise use Python, and the Arduino IDE and ecosystem are so well supported I, and do what I want so adequately, I haven’t much incentive to explore it.
 

Thread Starter

gchq

Joined Dec 27, 2023
69
Platfom.IO on VS Code is completely free. You might want to look at that.’
I did finally find some pricing at their site - a perpetual licence is based on the version of VS and since MS bring out a new version every couple of years it does look to be something of a pain to keep up with.

I will check out Platform.IO and give that a good coat of looking at.
 

Thread Starter

gchq

Joined Dec 27, 2023
69
It is illegal to tamper with vehicle external lighting.
It's more for the interest in recreating something from an old circuit board. What that person does with it - well shall we say I am not on a moral crusade. Technically it's not tampering with external lighting as that will still be OEM - putting addition LED lights on the back would certainly be a grey area, and laws do vary from country to country and the will to enforce some of them.

There are a host of off the shelf flashing systems, but they only work up to a maximum of 5 amps.
 

MisterBill2

Joined Jan 23, 2018
18,595
Tampering with a car's wiring" IS NOT ILLEGAL in the USA, unless one is a member of certain minority groups. Or live in some states under certain local governments. . Impairing the function of the systems is a different thing. Having to constantly live in fear of "The Man" is a separate issue completely. In a few otherwise civilized parts of the world there are rules about the credentials one must have to service a vehicle. I visited that country a couple of times, decent place to visit I would never choose to live there.

As for flashing lights on the rear of a car, I suggest that attracting attention except when avoiding collisions or impacts is a poor choice. "Bad Actors" have an inclination to remove parts and property from cars that attract attention. Even an engine or drive system, modified to deliver much more power than needed, is best not shown off, to avoid others removing parts and assemblies without my consent. Using that unannounced power when needed is quite adequate.

For tracing out that PC board schematic, a bright light behind the board will make the connections adquately visible to greatly reduce the effort to trace it out. But understanding the actual results on the lighting, and being able to describe it with common words will allow many folks here to come up with schemes to implement the effects in software quite well.
 
Last edited:

Audioguru again

Joined Oct 21, 2019
6,708
External lights on a motor vehicle have spec's for brightness, color and lighting angles. Turn signals have a spec for the rate of flashing. Brake lights do not flash but some new sports cars have the 3rd brake light flash. Police pull vehicles off the road until their external lighting is original.
Here in Canada teen's cars with blue lights are pulled off the road because only snow plows can have blue lights.
 

Ya’akov

Joined Jan 27, 2019
9,170
External lights on a motor vehicle have spec's for brightness, color and lighting angles. Turn signals have a spec for the rate of flashing. Brake lights do not flash but some new sports cars have the 3rd brake light flash. Police pull vehicles off the road until their external lighting is original.
Here in Canada teen's cars with blue lights are pulled off the road because only snow plows can have blue lights.
If the circuit is only used when parked, as extended hazard lighting, but never when the vehicle is moving, there should be no problem at all. That’s easily enough accomplished and it would have literally no effect at all on the specifications of the in-motion lighting.
 

Ya’akov

Joined Jan 27, 2019
9,170
I did try that - even propping it up with a light behind to get a pic.
This can be helpful but with a single sided board as trivial as that one it doesn’t take too much to trace anyway.

You can take two photos one of the obverse and one reverse, the flip the reverse one to it lines up with the obverse properly. Then you can overlay them with transparency, or, print them and use colored markers to indicate the hidden traces on the obverse photo.

Overall, it shouldn’t take too long if you still want to bother with it—even just flipping the board back and forth and, if needed, toning out any ambiguous connections.
 

Thread Starter

gchq

Joined Dec 27, 2023
69
Police pull vehicles off the road until their external lighting is original.
Upon what law, act or statute does that come under? There is certainly nothing like that in the US or UK.

Even with this, the external lighting is still original. It's just an override that may prove useful in an emergency situation.

Apologies if this thread is going sideways and away from circuits or general electronics.
 

Ya’akov

Joined Jan 27, 2019
9,170
Upon what law, act or statute does that come under? There is certainly nothing like that in the US or UK.

Even with this, the external lighting is still original. It's just an override that may prove useful in an emergency situation.

Apologies if this thread is going sideways and away from circuits or general electronics.
No need to apologize. The policy of AAC is that to the extent possible, the TS (Thread Starter, like “OP”) “owns” their thread. I calculating the off-topic phase angle for a thread, the bias of the TS is one of the terms.

So, if you are happy with the thread, and it isn’t in flames, or so far off from the original topic that the phase angle exceeds a ~180°, all is good.

By the way, I made up that phase angle biznatch oh the spot, we don’t actually do that—as far as anyone knows…
 

Reloadron

Joined Jan 15, 2015
7,523
Canada, Look under section 6 of the HTA (62.14 to be exact) you cannot use any red lamp that flashes other than for the purpose of a "four-way" flasher. This gets amusing as if decelerating which I see as braking and you are intermittently applying brake the end result is flashing brake lights. Approaching a stop and pumping the brakes the brake lights are going to be flashing. That is apparently acceptable.

Now here in the US my summer time ride is a '92 Harley Davidson Electra-Glide. Most of my lighting is now LED including brake lights. When I apply brake I have the brake lights flash five times in rapid sequence followed by constant on. Release brake and brake again the process repeats. This is perfectly legal here in the SE Cleveland, Ohio suburbs USA. I figure it to also be legal anywhere in the US. The idea being to get anyone behind you to be aware that you are braking / decelerating. Hopefully this gets them off their phone and texting. :) Seriously, it's an attention getter and on a bike you want motorist to know you are there. :)

Every time the subject of automotive lighting arises we have this exercise. Matter of fact when discussion of automotive lighting was a prohibited topic here in AAC.

Ron
 

Thread Starter

gchq

Joined Dec 27, 2023
69
Approaching a stop and pumping the brakes the brake lights are going to be flashing. That is apparently acceptable.
Before the advent of ABS, cadence braking was the only way to control a vehicle on ice. With Canada getting a lot of that slick stuff I would hope it is acceptable
 
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