# Suggestions for an easy way make a headlight modulator?

#### Steve Natt

Joined Nov 20, 2015
8
Anyone have any suggestions for an easy way make a headlight modulator on a motorcycle?
12v system, standard 3 wire h4 sealed beam headlight.
Looking for something TINY that can fit inside the headlight bucket with the rat's nest of wires already there, and that won't generate heat.
It would be great if I could have an onboard way to control the speed of the modulation (pulse is the wrong word to use here electronically, but that's what it looks like), for how many on/off events per minute... etc.

There are a couple of companies making these devices... one in the US here charges like $75 for it and it seems to me to be a rather simple device. There's some evidence that these enhance on-road safety by doing a better job of attracting the attention of distracted drivers... Thanks for any suggestions or advice. s #### shortbus Joined Sep 30, 2009 8,428 #### Alec_t Joined Sep 17, 2013 11,972 Welcome to AAC! 1) Assuming the common terminal of the twin-filament light is presently grounded, can you isolate it from ground? This would enable an easily-obtainable N-channel MOSFET to be used for switching both filaments. 2) Are you prepared to accept a reduced life for the light? Filaments don't take kindly to being repeatedly switched on and off. 3) Be aware that flash rates of about 7Hz can trigger epileptic seizures in susceptible people. #### crutschow Joined Mar 14, 2008 26,718 ................... 2) Are you prepared to accept a reduced life for the light? Filaments don't take kindly to being repeatedly switched on and off. ............................ I've had a headlight modulator connected to the two headlights on my cycle for well over 10,000 miles of driving and neither bulb has failed. I think the saving grace is that the filament is not completely turned off between flashes. The cycle is dim and bright, not on and off. #### #12 Joined Nov 30, 2010 18,217 There's some evidence that these enhance on-road safety by doing a better job of attracting the attention of distracted drivers... I saw one today and I told the driver, "Thanks for the blinky headlight. It's a lot easier for me to see where you are." ps, I'm not all that distracted when I'm driving. #### crutschow Joined Mar 14, 2008 26,718 I saw one today and I told the driver, "Thanks for the blinky headlight. It's a lot easier for me to see where you are." ps, I'm not all that distracted when I'm driving. Perhaps I'm dense but is the meaning of your sentence in quotes intended to be sarcastic? If so then you've never been on a motorcycle when someone coming at you makes a left turn right in front of you because they "didn't see you". #### JoeJester Joined Apr 26, 2005 4,390 I saw one today and I told the driver, "Thanks for the blinky headlight. It's a lot easier for me to see where you are. I can remember when motorcycles didn't have headlights energized during the day. The government regulations were changed to allow the headlights to be energized to make it easier to "see" the motorcycles, and it worked. Then true to form, it migrated over to all vehicles and the motorcycles disappeared into the sea of daytime lights. Now, some are "pulsing" their high beams for safety, and it's working. How long will it be before all vehicles are pulsing for safety? #12 #### #12 Joined Nov 30, 2010 18,217 Perhaps I'm dense Yeah. I think you are being dense right now. I said exactly what I typed in here today, and I said that to the driver. As for me being on a motorcycle, I am an amputee because of the drunk left turner that couldn't see me because he was distracted by his two previous DUI convictions. Last edited: #### JoeJester Joined Apr 26, 2005 4,390 Don't get me wrong, I think safety is utmost, but, I think transferring a safety for motorcycles idea for all vehicles only places the motorcycle back in an unsafe condition. I felt that way since the four wheel vehicles added daytime driving lights "for safety", pushing the motorcycles back into the shadows of the sea of daytime energized lights. I can remember the Italians in the late 1970s, warning everyone when their vehicle lights were energized during the day. Most thought it was wasting electricity. #12 #### crutschow Joined Mar 14, 2008 26,718 Yeah. I think you are being dense right now. I said exactly what I typed in here today, and I said that to the driver. As for me being on a motorcycle, I am an amputee because of the drunk left turner that couldn't see me because he was distracted by his two previous DUI convictions. So add some egg on my face to the denseness. When you used the term "blinky headlight" I misinterpreted that as sarcasm. Really sorry to hear about that drunk and what happened. I have absolutely no sympathy for repeat DUI offenders and think they should be locked up until they're too feeble to drive since they obviously have no consideration for anyone but themselves and are a menace to the rest of us. #### #12 Joined Nov 30, 2010 18,217 I have a tendency to be a bit too literal, and I assume the regulars notice that. In compensation, when I am trying a different approach I try to always add a smiley or [sarc/off] tag. Maybe this information will help our communication in the future. I do make mistakes, but I am willing to say so and learn from the moment...like when I missed that LM318 op-amp circuit earlier today. If you know Harley numbers, I owned UL3229 until I sold it for the down payment on a house. Yes, it was that cool, but I don't ride any more because I know I couldn't survive another hit like that. Besides, it's difficult to shift when your left leg is made of fiberglass. Everybody has an occasional fender-bender, but when you are on a bike, you're the fender. #### Alec_t Joined Sep 17, 2013 11,972 I think the saving grace is that the filament is not completely turned off between flashes. Ah, that would solve the perceived problem. I envisaged slow pulsing which would allow the filament to cool right down. #### crutschow Joined Mar 14, 2008 26,718 Ah, that would solve the perceived problem. I envisaged slow pulsing which would allow the filament to cool right down. The flash rate and intensity for a modulator in the US as listed here are: • The rate of modulation shall be 240 ±40 cycles per minute. • The headlamp shall be operated at maximum power for 50 to 70 percent of each cycle. • The lowest intensity at any test point shall be not less than 17 percent of the maximum intensity measured at the same point. #### BR-549 Joined Sep 22, 2013 4,938 And, “ The modulator switch shall be wired in the power lead of the beam filament being modulated and not in the ground side of the circuit.” #### crutschow Joined Mar 14, 2008 26,718 And, “ The modulator switch shall be wired in the power lead of the beam filament being modulated and not in the ground side of the circuit.” I don't understand the reason for that requirement. #### Alec_t Joined Sep 17, 2013 11,972 Perhaps the legislators didn't either . #### JoeJester Joined Apr 26, 2005 4,390 And tested in accordance with this profile: Conformance with the regulations drives the price UP. I suspect the "requirement" to tap into the power side vice the ground side is so you can "modulate" either the high or low beams without modulating the other when both filaments are energized. #### BR-549 Joined Sep 22, 2013 4,938 Do you feel safer now? That's the excuse for this intrusion. 10th Amendment is ignored. #### JoeJester Joined Apr 26, 2005 4,390 There are a couple of companies making these devices... one in the US here charges like$75 for it and it seems to me to be a rather simple device.
The devices are never as "simple" as we imagine.

In addition to the "requirements" stated by crutchow in post #13, there are theses additional requirements.

d.The modulator switch shall be wired in the power lead of the beam filament being modulated and not in the ground side of the circuit.
e.Means shall be provided so that both the lower beam and upper beam remain operable in the event of a modulator failure.
f.The system shall include a sensor mounted with the axis of its sensing element perpendicular to a horizontal plane. Headlamp modulation shall cease whenever the level of light emitted by a tungsten filament light operating at 3000 deg. Kelvin is either less than 270 lux (25 foot-candles) of direct light for upward pointing sensors or less than 60 lux (5.6 foot-candles) of reflected light for downward pointing sensors. The light is measured by a silicon cell type light meter that is located at the sensor and pointing in the same direction as the sensor. A Kodak Gray Card (Kodak R-27) is placed at ground level to simulate the road surface in testing downward pointing sensors.
g.When tested in accordance with the test profile shown in Figure 9, the voltage drop across the modulator when the lamp is on at all test conditions for 12 volt systems and 6 volt systems shall not be greater than 0.45 volt. The modulator shall meet all the provisions of the standard after completion of the test profile shown in Figure 9.
I wish you luck in your pursuit of this project.

#### JoeJester

Joined Apr 26, 2005
4,390
Do you feel safer now? That's the excuse for this intrusion.

10th Amendment is ignored.
Hate to be the bearer of sad news, but the 10th amendment has been in shambles for a very long time now. The requisite due diligence wasn't there when it was being trampled on. We federalize too much stuff. The object of being a collection of independent states is no more.