quick question

[bowser22]

do headlights on cars flicker or dim at all from the dc ripple?is this a linear ripple if so?
Thanks

 

[stevez]

It's possible that the ripple from the alternator results in a subtle flicker -one fast enough that your eyes can't sense it. It's also possible that the thermal mass of the filament dampens the flicker to a certain extent. At one time I fashioned a "light listener" from a Cds photocell, a 741 op amp followed by an LM386 audio amp. That revealed flicker in a lot of things and might do the same in this case.

 

[RCinFLA]

The alternator provides a pretty constant regulated voltage of about 13.8 vdc.

There is a little ripple associated with the three phase, full wave rectified alternator output but this is relatively high frequency (if you have ever heard alternator whine in a car radio) which is much higher in frequency then the headlights would be effected by.

 

[bowser22]

i had an idea that if i could figure out the flickering in the headlights that i could know what kind of alternator was in the car and since police use different higher power alternators i could therefore detect police cars through headlights

 

[ke5frf]

Like an alternative to radar detection?

Even if this were possible, you'd have to be awfully close before your detector even sensed the headlights.

I believe the "flickering" that you see when a vehicle approaches is more related to atmospheric "filtering" at a distance (heat distortions, water vapor and condensation) as well as shock absorber bouncing and vibration between the two converging vehicles than any alternator ripple.

 

[bowser22]

i was only panning on using this on vehicles within close proximity in the night time anyways

 

[Pommie]

It would be much easier to detect the blue flashing lights.

Besides, high power alternators don't cause any more flicker than low power ones. In fact, probably the opposite.

Mike.

 

[KMoffett]

do headlights on cars flicker or dim at all from the dc ripple?is this a linear ripple if so?
Thanks

If your question is related to observing headlights coming toward you flickering, it's most likely a bad/loose headlight mount. The headlight holder is just rocking up and down with road vibration. Dimming can be caused by corroded wiring harness contacts, usually at the lamp base.

Ken

 

[bowser22]

i understand that though, ive seen them flicker from other things and i know regular headlights dont. i was wondering if regular headlights flickered at a rate faster then what i could comprehend because of the ripple then i thot about how it could be applied to identify cars.

 

[smanches]

Since newer cars are have the HID headlights, that would throw the whole system off too.

Would probably be easier to write software to do image analysis and determine the type of car from the light profile.

 

[bowser22]

aha i actually thot of that as well but i cant write software at all