The leftmost and rightmost amber lamps I connected to the vehicle turn signal circuits.
Works well, but at nightoo bright for drivers stopping behind me.
They operate on 12VDC.
Anyvay to electronically dim them?
The LEDs are mounted on circuit boards containing sophisticated circuitry containing microelectronicomponents. I am not even able to discern the circuitraces.
Thank you.
You might be able to put a potentiameter into the power that supplies the bulbs,
LEDs do not respond well to dimming. Your LEDs probably work for voltages between 6-30 volts with little difference in brightness.
Is this the OEM light bar or something you added? If it is not OEM, thne you need to remove it, it isn’t legal.
If it is OEM, then it shouldn’t be too bright. But one way to dim it is to lightly spray black paint over it. You have to clean the plastic cover and then spray a special bonding agent on it. The you get a black spray paint that is OK for plastic and vary lightly spray over the lights. Keep it even and VERY light coats until the desired light transmission is achieved.
I would get some tinted gel, like for DIY tinted windows.
Multiple layers will make it dimmer if one layer isn’t enough.
Easily reversible.
You vary the brightness by adjusting the current. That can be done by changing the source current limiting resistor or by using a pwm source. It’s done all the time. I even put a potentiometer on my kid’s nightlight as it was far too bright. Same with my bedroom clock although the varying number of led segments was causing variations in brightness so I redesigned the supply to constant current source and viola!
That can be true of light assemblies with a built in driver/regulator.
That’s true of “raw” LED devices.
So you guys are both right, but in different context.
(Back from a 9-houround trip bloodelivery and must sleep.)
These are the amber lamps in law enforcement light bars which sequentially directraffic left or right.
Not needed so I connected the left and right end lamps to turn signal circuits.
Ideally at night a DPDT switch could send turnsignal 12 VDC through current-limiting resistors. But I do not knowhat resistance is needed to limito what current.
Was thinking of making a circuit which would flash the LEDs at a high frequency of 25% ON, 75% OFF. But what would that do to their circuit board behind each lamp? Have no idea of why such sophisticated circuitry. (Maybe I can attach a photo.)
Thank you.
Most volunteers don’t have the need to tell about their activities all the time .
Depends on how much bulk capacitance it has on the input. You can try pulse width modulating the supply to see if it can be done without removing some input capacitance. I have some add on LED lights on my snowblower that were blinding bright. They have built in regulation. I made a little circuit to modify the input duty cycle so I have a 50% mode I can switch on… YMMV.
'Splains why so late responding to comments in the topic I had justarted.
@Robert_Gift, if you have been authorized to have these lights on your vehicle, then you have a public trust to use them as designed and only for the purpose they are authorized for. Any other use or modification is a violation of public trust and it can carry a very heavy penalty. I suggest you rethink this idea of using them for turn signals.
I had light bars installed on my work vehicles, yellow only. Would not think it a danger to risk police intervention to install yellw light bars on my personal vehicle. @Robert_Gift what colors are yours?
In my state light bar’s can be yellow or white on a work vehicle with a yearly permit from the DOT for 3$ a year for each vehicle.
But does you state allow them to be modified for a different use than intended?
Yellow flashing lights I have used driving around to make sure sewers are not surcharging. Not sure what you are asking.
@Robert_Gift wants to modify the yellow lights on his vehicle to be turn signals. I don’t know why he would want to do that but that is not their intended or authorized use. I think he is breaking the law by doing this and I was trying to warn him so he doesn’t find himself in trouble. He does seem to me to be a very good citizen, volunteering to transport blood at his own expense, niot the kind of guy I want to see in court at the wrong table.
The only thing that can be changed it the pattern of strobe light’s
The yellow lamps in the light bar may emit several different patterns to the rear.
Sequentially Lefto Right, Righto Left, starting in the middle and diverging out.
All flashing On and Off, maybe others.
Since themergencyehicle does not stop on a road or athe side of a road, none of these patterns are needed. Though the light bar controller has buttons for different patterns, I would never operate any.
The twoutmost amber lamps are now connected as turn signals. (They match the vehicle’s yellow tail turn signals.)
After midnight last night, coming upon a herd of deer on a mountaihighway, I turned on the four-way-flashers. The amber lights worked well at warning the semi rigs following well behind.
When emergency transports (red, white, blue lamps flashing) the amber turn signals arespecially useful for changing lanes or entering or exiting Interstate highways.
They are legal, but I wanto find a way to electronically dim them at night so notoo bright
in theyes of driverstopping behind.