OK guys,
Too much time on my hands of late, so additional thoughts of somewhat radical modifications to the FrankenVette are dancing in my head. I have always thought the fiber optic system on the pre 72 C3s were way cool and also provided a practical solution of knowing if a bulb is out. I guess the straight forward way to modify my 72 to acquire this feature is to accumulate the stock components and install. However would there be an “easier” way by possibly using LEDs for the indicators, and some way of wiring to get the proper signal for illumination? My OHMs law facts are almost null and void, but it seems there must be a way? Additionally as I believe the stock system supplies illumination when all is well, I would like illumination when a particular bulb is out. In my remedial reading brain, it seems a few LEDs, some light wire runs, and a couple of relays seems a lot less expensive than duplicating or modifying original. Any ideas?
Thanks

 

The fiber optic system collects photons from the stock lights, sends them through fiber optic cables, and then displays them for the driver in the cockpit. You could easily rig up an LED display that mirrors what the lights should be doing, but that doesn't show if the bulb is burned out. Some Modern cars have CAN Bus enabled bulbs that talk to a computer, but I doubt you want to do that.

So you need to measure photons from your bulbs to trigger the LEDs. Here's a $0.65 circuit that should measure light, and return a voltage if it above an adjustable threshold. The return signal should be sufficient to power an LED directly. You'd need one board per light to be sensed. There are other boards that return an analog signal as well, that could be used with an Arduino.
https://www.aliexpress.com/item/32764113833.html

The "easiest" way to do this without a helper is to put a few mirrors or cameras in your garage. I'm sure @Richard454 will now show a working system from his car.

 

Thank you Bikespace! Could this arrangement be configured to show a light out situation? Your probably right, we should just wait for Richard’s finished result

 

You could also contrive some sort of open circuit detection by putting some resistance in line with each bulb. The annoying part of any scheme is running wires back to the console. So this putative open circuit detector might want to include a little logic to determine exactly which bulb was out. Going a little further, you could bluetooth your way to the console LED's. There's another wireless standard called ZigBee. Possibilities abound.

As my old boss used to disparagingly say when I'd propose something like this: "sounds like a science experiment to me!". With enough time on my hands I might actually have wanted to try this, except, my car already has working fiber.

 

I should think that the light detector I linked would do what you want. I am speculating, though.

At night, and without the sun, a streetlight, or someone else's headlights shining into your housing, you would be able to adjust the trimpot to send back a signal if it sees your headlight lit, and no signal if it is off. You may even be able to trim it to work during the daytime, at least for the headlights that are hidden in the closed position. Like the fiber system, you will get false positives. Unlike the fiber system, you may notice LEDs turning on and off during the daytime. Also, you will need to mount the photoresistor facing the bulb element, and keep the electronics dry, problems the fiber solution can easily avoid.

I usually check my headlight reflection off of the car in front of me.

 

Bikespace thanks for your follow up. I can see your understanding of the black art of OHM’s law clearly exceeds my own in spades. I would think the system would be more useable, at least for me, if it’s feasable, to have a bulb illuminate when the light that is monitoring is out. I am less concerned about headlamps as tail or brake lights more important for my use. I have noticed when my brakes or turn signals are on, my voltmeter shows a reaction( replaced ammeter a while ago). Could not something be put in the circuits that detects a change in voltage/ current that could provide a source for illumination?
Thanks again for allowing me to scratch your brain. Then again, you could be merciful, put me out of my misery, and tell me to forget it Much appreciated.
Dave

 

Ignatz thanks. When you find the time could you please elaborate a little further on this solution? As stated, myself and electron management don’t usually speak the same language. Could you explain it to me as you would a 12 year old. I think ultimately, I would like the bulb out indication if within my realm of understanding and competence.
Thanks again!

 

You could certainly design another circuit that reverses the signal to power LEDs when the bulbs are not lit, but should be (the opposite of how the fiber optics work). This could be a normally closed relay, with the main feed powered by the IGN (or even the brake/headlight circuit itself) to your LED, The signal from the light detector circuit powers the coil, and keeps the contacts open when light is detected. If light is not detected, the coil is not energized, the contactors close, and power flows to your LED indicator.

That's way too much work. You'd simply go to an Arduino board instead to read the signals, and save needing two circuits for each bulb detection. The Arduino could then display on an array of LEDs, or even on a screen, if any bulbs are out. Neopixels work great for this, as an Arduino can control tens or hundreds of RGB LEDs from a single output. For example: https://www.adafruit.com/product/2868

Your circuit monitoring method sounds much simpler. To detect the current on each line, I'd use a shunt, and an Arduino. You'd need to measure the expected voltage drop across the shunt, and program the Arduino to alert you if it falls out of that range. You'd have to reprogram the range(s) if you changed the bulbs, but I think it is doable. Just thinking about doing this much work for a brake light is making my head hurt, but most of it is programming, and adding some shunts to circuits.

If you are looking for a fun lockdown project, teaching yourself how to program Arduinos can be fun. Pick the right kit, and you'll learn some electronics, too. This is as far as I've gotten with my Corvette dash replacement, but in the picture you can see two Arduinos, one for a GPS-based digital speedometer (my dining room table is moving at zero mph, but it is working), and a second Arduino to display a startup image for a monitoring display screen, as if GM had continued C3 production into the 2000s. Everything is powered from the 5V USB battery.

 

 

Anything is always possible and as long as you're doing it and doing it for yourself the cost/return is fairly irrelevant




If you want to drill into the light housings then adding some phototransistors and running a bunch of wires back to the console, then either use some discrete components or a small microcontroller it's fairly simple to get some LEDs to light or use a display.
You could also tie into the circuit inside the car and check for an open / closed loop as mentioned above by ignatz, you should at least be able to "see" what corner is out but maybe not if it's the side or front light and it does some weird reversing when the parking lights are one but I'm sure it's doable

It's these little projects that make the winter go by
M

 

If all else gives you a headache, buy a roll of optic cable in the diameter you need on eeeeebay and run it to the console

 

I'm going to totally ignore this thread...as an old engineer once told me ( OK many times!!!) you can't hit a moving target...As I want to eventually finish my car AND the original fiber optics work fine!!

Here's a thread a while back-
https://www.corvetteforum.com/forums...to-a-79-a.html

Just sayin- for about $50 you can by enough fiberoptic cable to do the whole car. (32 -55 cents/ foot)

http://www.fiberopticproducts.com/

http://www.fiberopticproducts.com/Fiber_optic_items.htm


Here's some ends- $5/each

http://shop.fiberopticproducts.com/i...roduct_id=1253





https://www.superbrightleds.com/more...mount-red/301/

And for 32 cents each - get some LED lens mount

 

Thanks everyone for their continued help. I have a caveat to confess. I have modified my taillights with LED rings for lights only.Additionally I have incandescent bulbs in all 4 now for brakes and turn signals as I have changed over the back up lights to brake/ signal lights, so now two brake/signal lights instead of one on each side.
Whereas ordinarily it would seem much easier to quasi duplicate a fiber optic system, because I have two separate light sources for each tail light, any photo sensing or fiber optic solution would not work. ie taillights work but brake/ signal light burned out. Additionally, if the design group has their way, I would only like to have illumination if a bulb is out, not when it is
on. I believe an electric solution is possible, but I have very limited knowledge of circuit design and virtually zero understanding of can bus. Wrestled with those systems in Jags previous, and forced me to drink. Please keep the ideas coming. Very much appreciated!

 

Would it be possible to wire into each light circuit and have it power a relay that powers an LED if the circuit opens (burned out bulb?) That may seem cumbersome, but intuitively it seems doable. What say you OHM’s law grads?

 

I can't think of any way to do it cheaper than what @Richard454 suggested with new runs of fiber. You could absolutely do it with an Arduino and some current sense circuits, but you'd have to do it yourself, and it would need to be your new favorite hobby. You'd be breaking circuits to put in shunts (or use crazy-expensive DC current probes), so you'd be just as likely to cause a wiring failure than detect an LED bulb failure.

Glib suggestion: It would be cheaper to hire an Uber driver to follow you for a mile once a month and tell you if your lights are out.

Serious suggestion: Put an Amazon Blink camera in your garage.

 

I saw this after I posted my previous reply.

I found some example circuit diagrams online that do this. They seem to rely on a single bulb element failure. Since you have LED arrays wired in parallel, a failure of one array element, or even of one "bulb", would not trigger these circuits. You would need once circuit, and LED, per "bulb", or you would still need to detect the current drop. My taillights are wired the same way (68 or C5 style), but use 1157 LED bulbs in parallel (left turn signal active below).

 

Someone probably already said this: Ground EACH light independently to the frame.
Splice into each ground wire and run the spliced wire to the center console.
Install a One Way diode into the Ground wire for EACH light.
Connect a $5 relay (NO or NC depending on your taste) to EACH independent Ground wire from each light so that the appropriate console warning light either turns ON or OFF, depending on how you wire EACH relay.
Theory is: A Light burns out...the One Way diode causes the Ground wire that runs to the console warning light is either turned ON or OFF (depending, again, on your taste) when the relay is grounded.

WAIT.....I just confused myself

 

Being an electronics engineer I can think of a few circuits that will indicate if a bulb is burnt out. Wouldn't be that hard. With that said I think the easiest way is to just source the original stuff or buy a '68-'71....

 

 

I have to agree. It wouldn't be hard to find a burnt out bulb and maybe make something blink on the console to show which one it is. That would be useful of course, but who wants useful? I think the cool factor is that you are actually seeing light from from an illuminated bulb with the optical path through the fiber. After imagining various ways that could be simulated, the reality is there is no better way than to run the fiber lines. And that very nicely, is completely passive. No messy "OHMs law facts"