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You're correct. I will just use them for HB, they are bright for driving at nite. I got LEDs for the parking lights and they seem to work, it is annoying with all the brite LEDs running around everywhere tho.
 

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Not exactly- as HaloRuler said before, Spyders use a lower voltage for DRL rather than PWM. I haven’t confirmed this myself but it makes sense.(It’s also possible something else is going on, I’d have to scope it.)From my read on it, this voltage must be close to the threshold for the LED to operate, and the flickering is due to fluctuation in the voltage due to nonlinear effects in the circuit, quite possibly just non-ideal performance of the rectifier. LED and other diodes tend to continue conducting at a lower voltage once they are conducting, so that’s why once they are on in a steady state it will stay on.
The capacitor is still smoothing things out, but not smoothing a PWM just smoothing fluctuations enough to keep it conducting.
 

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Anyway, this is possibly a solvable and doable thing. It is pretty damn cheap to put together a small component, just look at the magic Marc has worked on his much more complicated problem. You just have to do it hobby style and not be paying yourself EE salary!
 

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Not exactly- as HaloRuler said before, Spyders use a lower voltage for DRL rather than PWM. I haven’t confirmed this myself but it makes sense.(It’s also possible something else is going on, I’d have to scope it.)From my read on it, this voltage must be close to the threshold for the LED to operate, and the flickering is due to fluctuation in the voltage due to nonlinear effects in the circuit, quite possibly just non-ideal performance of the rectifier. LED and other diodes tend to continue conducting at a lower voltage once they are conducting, so that’s why once they are on in a steady state it will stay on.
The capacitor is still smoothing things out, but not smoothing a PWM just smoothing fluctuations enough to keep it conducting.
@Biomed&Barolo: Can you explain a bit more? I'm assuming the pulse wave is a square wave going from zero to +12? I'm trying to figure out exactly what's going on with the cap. I know tied with a resistor it becomes a timing circuit and in an analog circuit it will pass a frequency and block DC. But how does it function here to smooth the pulse?
 

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From this wiring diagram, it does not look like the Spyder uses PWM.
I would draw the opposite conclusion. The alternate ground for the headlights just disappears into the control module. If there were a voltage dropping resistor, then it should be outside of the module since it is a significant heat source. The only alternative is that there is a switching transistor inside the module. There could also be a complete switching regulator in the module, which would be a switching transistor combined with an inductive filter. That would produce a DC output, but there would be no reason to do so because the incandescent lamp is a perfectly good filter for this purpose.
 

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... LED and other diodes tend to continue conducting at a lower voltage once they are conducting, so that’s why once they are on in a steady state it will stay on...

...The capacitor is still smoothing things out, but not smoothing a PWM just smoothing fluctuations enough to keep it conducting...
You are thinking of arc lamps. They have an ignition voltage, and a much lower conduction voltage. Diodes have a fixed threshold for conduction that does not change.

The characteristics of a diode in a circuit depend entirely on what kind of ballasting that it has. If the diode is a plug in substitute, then the ballast is incorporated in the unit, and there is no point in speculating about its behavior in a pulsed or low voltage circuit until the ballast circuit is known.
 

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I did not realize such a dumb idea of mine has generated some considerably advanced discussion of EE. I am impressed with all the responses, regarding this subject of which am of great interest. I'm just a regular construction dude and as they say in the Army, carry on.
 

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I would draw the opposite conclusion. The alternate ground for the headlights just disappears into the control module. If there were a voltage dropping resistor, then it should be outside of the module since it is a significant heat source. The only alternative is that there is a switching transistor inside the module. There could also be a complete switching regulator in the module, which would be a switching transistor combined with an inductive filter. That would produce a DC output, but there would be no reason to do so because the incandescent lamp is a perfectly good filter for this purpose.
What am I missing? Looks to me like it's just 12 volts going through the relays and switches to light the lamps. Can you reference the diagram on the control module you're referring to? Keep in mind I'm an old guy and it's been a lot of years since I've followed wiring/circuit diagrams.
 

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I would draw the opposite conclusion. The alternate ground for the headlights just disappears into the control module. If there were a voltage dropping resistor, then it should be outside of the module since it is a significant heat source. The only alternative is that there is a switching transistor inside the module. There could also be a complete switching regulator in the module, which would be a switching transistor combined with an inductive filter. That would produce a DC output, but there would be no reason to do so because the incandescent lamp is a perfectly good filter for this purpose.
That’s why I’m not totally sold on the truth of using a constant lower voltage– a resistor is inefficient and a buck converter is unnecessarily complicated when PWM would suffice.
I’ll have to glance at that diagram when I’m home.
I think I mentioned before but I’m pretty rusty on EE because it’s not my discipline. One of these days I’ll have to do some refreshing.
 

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What am I missing? Looks to me like it's just 12 volts going through the relays and switches to light the lamps....
The DRL function requires running the standard headlamps at reduced power. That can be done in two ways: Either by including a series resistor to reduce the voltage, or by the PWM method which is switching the circuit on and off rapidly to reduce the average power. Since no resistor is visible on the schematic, I am assuming that it does not exist. It would generate significant heat, and it would be poor engineering to put it inside another module unnecessarily. That leaves the PWM method. There would be a switching transistor inside the module, but would not produce the same heat because the transistor is always either full on or full off, and hence in principle does not use any power.

Of course, these are just assumptions about the cheapest and most efficient way to solve the design problem. Who knows what Toyota actually decided to do.
 

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The DRL function requires running the standard headlamps at reduced power. That can be done in two ways: Either by including a series resistor to reduce the voltage, or by the PWM method which is switching the circuit on and off rapidly to reduce the average power. Since no resistor is visible on the schematic, I am assuming that it does not exist. It would generate significant heat, and it would be poor engineering to put it inside another module unnecessarily. That leaves the PWM method. There would be a switching transistor inside the module, but would not produce the same heat because the transistor is always either full on or full off, and hence in principle does not use any power.

Of course, these are just assumptions about the cheapest and most efficient way to solve the design problem. Who knows what Toyota actually decided to do.
So on an 00-02 the pulse duty cycle would change when going from DRLs to full on? I mean that does make sense.

I'd love to change my (new to me) '01 to projection (even with halogens) but I don't drive enough at night to justify the cost.
 

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Over my morning coffee I noticed something... page two of the diagram! DUH! Now I see the control module and also ICs in the diagram. Yeah, I bet it's PWM.
 

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So on an 00-02 the pulse duty cycle would change when going from DRLs to full on? I mean that does make sense.

I'd love to change my (new to me) '01 to projection (even with halogens) but I don't drive enough at night to justify the cost.
Yes, that makes sense. The diagram indicates that with headlights full on, the lamps get a hard ground through a relay, which is effectively 100% duty cycle. With the headlights off, the lamps ground through the control module, which does whatever mysterious things that it does inside the black box.

Keep in mind that in the 00-02 cars the DRL uses the low beams, but in the 03+ cars the DRL uses the high beams, since the lows have been replaced by projectors.
 

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Thank you all for the most interesting discourse on this subject and your contributions to this thread. Altho I am not an engineer by trade I love and enjoyed every bit of this discussion.
 

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Being in the construction biz, I used to look at parking lot light fixtures and they would have photometric data on how the light is distributed and lumens. If only there was a way to do a similar test and have real world data on different ambient light conditions and measure "glare" the LEDs emit would be useful. Just a thought. But I think we beat this horse quiet thoroughly here.
 
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