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post #1 of 24 Old 01-22-2010, 11:36 PM Thread Starter
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PWM in the JK

I've been reading about Pulse Width Modulation (PWM) and was planning to do a write up about PWM and some thoughts on how to run auxiliary lights off the battery consolidating posts here and elsewhere using relay switched by various things - including the high beams.

There are some people posting that putting the plus side of a relay coil on the high beam line may damage the JK. Can someone explain it to me what the concern is and what the electronic issues are? I'm just not getting it.

I have a recording multimeter and a recording USB oscilloscope I use in my work projects (for the fellow computer techies out there, MSO-19 oscilloscope www.linkinstruments.com - $249 is very inexpensive and company is great to deal with).

I've done projects involving PWM motor control so I have some familiarity with it but I'm by no means a degreed electronics engineer.

A simplified explanation of PWM is the voltage is pulse because things like motors and lights don't care. One advantage is the on/off pulse provides a method that a microprocessor can monitor and control the device (because digital logic has two states - 0 (a.k.a. off) and 1 (a.k.a. on). Another advantage is a smaller gauge wire can be used since pulsing uses a lot less energy and produces less heat than "always maximum on".

Here is the JK normal high beam lights. With a multimeter ~11 volts (my JK idles at ~14.3 volts). The amount it pulses high (Duty Cycle on my meter) is 78% of the time. Low beams measure the same. So our stock headlight voltage input is 22% less than it would be without PWM - which might be part of why the stock headlights suck


For our Canadian friends, it was mentioned to me that my AEV Procal will enable the Daytime Running Lights (DRL) that are mandatory for them and I ran some experiments.

Now here is the DRL. With a voltage meter ~2.6V volts and ~18.5% Duty Cycle. The Daytime Running Lights are of course dim compared to the 79% Duty Cycle of turning them on at night.


As you can see - the amount of time the voltage is "on" is far less. I was expecting more towards 6 volts but it measures the same whether DRL is high or low beams.

Now back to my relay question. I have a Radio Shack automotive relay (they likely get it from Bosch or one of the other manufacturers). I run my HID lights directly off the battery - but I have the relay coil connected to the headlight high beam line. So when my high beams are on - my HID used as driving lights come on (yes that is weird - California Law of course).

The relay measured 125ma draw. Variance in your headlight bulbs are more than that - so that can't be an issue. Across the relay coil is 85 ohms but the headlamp bulb is just 0.2 ohms to ground. When the relay trips - don't see the 85 ohms as the electro magnet activates to trip the relay. I ran measurments with relay in and out of the system - can't find anything different.

So - I know there are some tech heads here - can someone explain to me what I am risking tripping the relay off the high beam line? I understand no vendor wants to take on liability concerning the JK network computer so they can't say "do this" - but is there a real electronic theory concern?

(Edit: BTW, I was going to use a PAC TR7 universal trigger module to trip the relay so the relay is electrically isolated - but then wouldn't the TR7 bring the same concerns? I can protect the high beam line from any relay failure instead with a fuse/diode.)

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post #2 of 24 Old 01-23-2010, 03:18 AM
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i have the high and low beam operating two tyco relays, i have no issues. i used to be a mecp installer. if it messes something up from something that trivial i have 3 five gallon gas cans and a match.

i really dont see how using the supply wires as relay triggers can hurt anything, i suppose if you didnt utilize the needed capacitor and diode but ten it wouln't work right anyway

i think with the equipment that you have and the values posted above that you could verify that the capacitor that most of us are using is the correct size andis not under or over sized, thus the bulb still pulsating but to the point we cannot tell by sight. there are many including me that have had bulbs go out prematuraly for no reason and it could be due to slight or extremely fast pulsing.

now if you can figure out where th bck feed is coming from on the hids to where it messes up the fm signal you will make many people happy. i don't see how it leaks in voltage to the radio when the ballast and high voltage wires are way away from each other.
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post #3 of 24 Old 01-23-2010, 05:02 AM Thread Starter
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Quote:
Originally Posted by rob4607 View Post
i have the high and low beam operating two tyco relays, i have no issues. i used to be a mecp installer. if it messes something up from something that trivial i have 3 five gallon gas cans and a match.
ROFL - I feel the same way. Since I have done computer stuff for many years I've been wondering what kind of lame networking implementation is in these things...

Since you were a mecp you probably have messed with the PAC TR7 (or TR4) trigger with audio installs.... I'm going to buy one because I've never messed around with it and I know I'll find a use.

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Originally Posted by rob4607 View Post
i really dont see how using the supply wires as relay triggers can hurt anything, i suppose if you didnt utilize the needed capacitor and diode but ten it wouln't work right anyway.
I don't even get the capacitor diode thing for the pulses. At 78% Duty Cycle it should trigger a relay unless the relay has a very low or very high voltage trip spec. These older style automotive relays don't drop out quickly and you have to have at least 7 to 8 volts. http://www.radioshack.com/product/in...ductId=3020762

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Originally Posted by rob4607 View Post
i think with the equipment that you have and the values posted above that you could verify that the capacitor that most of us are using is the correct size andis not under or over sized, thus the bulb still pulsating but to the point we cannot tell by sight. there are many including me that have had bulbs go out prematuraly for no reason and it could be due to slight or extremely fast pulsing.
When I put the relay in or out of the system with no capacitor- nothing changes. I can try the capacitor - what value are you using, I probably have it. Wouldn't that be a trip if adding a capacitor changes things because it is oversized... tell me the relay part number too so I can check its specs - but as you say, if small resistance/inductance screws these things then its gas/match time.

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Originally Posted by rob4607 View Post
now if you can figure out where th bck feed is coming from on the hids to where it messes up the fm signal you will make many people happy. i don't see how it leaks in voltage to the radio when the ballast and high voltage wires are way away from each other.
Not sure what you mean. I don't get noise with my bumper HIDs wired with the relay by the headlight - I get it AM and FM with my windshield set. It is due to my passenger side HID being next to the antenna - the high voltage is "broadcasting" to it. Do you mean your windshield HIDs or bumper or??? I can probably stop or make it not so noticeable - maybe ferrite bead the ballast leads.... describe for me the problem you mean and I'll run an experiment to try to come up with a fix. My handheld HID does it 14 inches or closer to the antenna.

While it did remind me of harmonics from spark transmitters, Tesla coils, and the beginnings of radio - I'm getting old but not that old!

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post #4 of 24 Old 01-23-2010, 04:40 PM
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Quote:
Originally Posted by Rednroll View Post
can bus
If I'm not mistaken, the shiny vertical metal box in the front driver's side quadrant of the engine bay is called the TIPM (Totally Integrated Power Module) and is essentially a bank of mosfets/SCRs/Transistors connected to the CanBus. When the canbus says "headlights on" this is the box that puts the pulsed DC out to the headlights.

An aside on the relays - When I did my HID kit, the HID relay was connected to the factory headlight connector, but when the motor was running, the HiBeam relay would emit an audible buzz, as a direct result of the pulsed DC being discussed above. I put a capacitor in parallel with the relay, to tank the charge when the pulse is high, and release it when the pulse goes low. This had a side effect of introducing a delay when turning my highbeams off, so I tested with progressively smaller capacitors until I found one with an almost imperceptible delay.
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post #5 of 24 Old 01-23-2010, 09:07 PM Thread Starter
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Rednroll - thank you so much for posting!

Back-EMF with motors I am more familiar with and is a serious concern, After further thought, the 12V relay coil winding is more substantial than at first glance (duh) so I realize now it could store enough energy to cause an issue. So the diode/fuse I mentioned will protect the system from the relay:

- diode, "inverse parallel" connected to the coil pins to absorb the reverse voltage energy on the relay coil when power is pulse/switched off. (NOTE: diode inverse parallel - i.e. the negative/cathode/line side of the diode is connected to the positive 12V supply side of relay coil terminal and the positive/anode side of the diode is connected to the ground side of the relay coil.)

- fuse, series connected to coil positive supply pin (in case of any bizarre relay short scenario).

Some are getting chattering which I assume is partly caused by using a relay that needs very little voltage to activate combined with having a fast drop out. My Radio Shack relays don't have any problem.

Aside from building stuff, in a previous life so long ago I've forgotten everything - I rep'd Aromat (Panasonic) relays and they have a guide at: http://pewa.panasonic.com/pcsd/tech_info/pdf/rti.pdf

Given the inverse parallel diode method increases relay release time - isn't that going to fix the PWM issue?

The way of handling the PWM chattering is described here:
https://www.jkowners.com/forum/showthread.php?t=10665
https://www.jkowners.com/forum/showthread.php?t=10630

The diode is in series with the relay coil positive line and the capacitor goes across the coil pins in parallel. The inline diode is suppose to stop the back EMF, however, I read induction can still cause voltage spikes in adjacent wires.

DSY's diagram says "220pf electrolytic capacitor" but it is 220uf (microfarad not picofarad). Others use 100uf instead. I am wondering - how high is the voltage/current on the back EMF and is it degrading the electrolytic over time - I've seen photographs of spikes blowing holes in aluminum-paper electrolytics. I am not a fan of putting something that will eventually fail shorted there - need to at least add a fuse to that line or risk wiring damage. Electrolytics fail short and catastrophically if voltage is reversed (good firecrackers - I've seen many a PC board with a hole blow clear through it from tantalum electrolytics - also ceramic bypass capacitor failure does it)

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Originally Posted by Rednroll View Post
I think there is something wrong in your O'Scope setup.
Very good - you caught my laziness with the scope interface software! You have the eye for detail, natural curiousness, combined with the ability to explain to lay people - not as common abilities as you may think.

The probe that comes with the scope is a manually switched 1X-10x-ref probe I had in 10x. The software also can autoswitch the probe but I had that tuned off. I should of photochopped off the text since I was just using it for the waveforms and didn't change the headings for my manual messing around - in "Auto" mode it updates everything for you - my bad, just takes a second to fix.

"connected to the CAN Bus" - now you'll hate me. I do research mostly in IP litigation, electronics patents. When an engineer speaks - you spent a lot of time and money learning the language of precision. When legal speaks - precision is a myth. So, courts have ruled in electronic patent claims "connected to" means "directly or indirectly". Doesn't matter if it is electrically isolated through 20 semiconductor components. Engineers that make it into patent litigation as an expert witness get paid $300/hr to $800/hour - a lot of money but few can do it - requires rewiring the brain into mush or another way of looking at it, an exceptional intelligence to learn the fine art of throwing pearls to swine. In your second post you say "directly connected" which works for most people (including me) but of course there is another patent claim legal argument about what that means. In my world, the spark plug is connected to the tires and even "directly connected" is still open to legal argument. Sad.

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Originally Posted by Gavitron View Post
This had a side effect of introducing a delay when turning my highbeams off, so I tested with progressively smaller capacitors until I found one with an almost imperceptible delay.
What value did you settle on?

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post #6 of 24 Old 01-24-2010, 12:34 AM
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Originally Posted by chasinternet View Post
What value did you settle on?
IIRC, it was 220uf, because I had one on hand. (I started @ 4700uf!) I probably could (should) have gone lower, as I can still sense the delay, but it's in the order of microsesconds, so close enough.
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post #7 of 24 Old 01-24-2010, 05:25 AM Thread Starter
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My electronics brain cells are slowly coming back online - Rednroll's high school fun and getting familiar again with the Panasonic relay notes reminded me of Tesla's bifilar coil winding patent to stop Rednroll's "fun". There is a reason relays rarely use bifilar windings, however, and my "inverse parallel" diode solution has a similar problem.

When the coil current is turned off "break bounce" may be a consequence since coil current doesn't necessarily return to zero in a linear way. It goes rapidly down then bounces back up before zero - which sometimes means the contacts get suspended in a partly/nearly closed condition that causes arcing (arcing destroys relay contact surfaces) or pulses completely on then off. I'm not as concerned about contact arc with just 14 volts at 6 amps on a 40 amp relay - but if it pulses the HID ballast as it bounces - not good.

I hate the electrolytic solution - but that is due to my knowing more about capacitors than the PWM drivers and voltage protection in a Jeep. An electrolytic is going to fail - but it may take a few years which is why no one is complaining yet. If it just bursts, no biggie, but if it explodes taking out surrounding wiring - that gets expensive. Blown HID ballasts from constantly pulsing when turning off is expensive too.

Tyco has a couple of good app notes:
"The application of relay coil suppression with DC relays"
http://relays.tycoelectronics.com/ap...fs/13c3311.pdf
"Pulse Width Modulation (PWM) & Relays"
http://relays.tycoelectronics.com/ap...ation_note.pdf

Tyco electronics has it as:
Coil suppression
"For single drivers the best compromise is probably an anti parallel low voltage (3…9V) Z-diode. A Zener diode in parallel to the driver would cause a varying voltage clamp across the relay coil during switch-off due to varying supply voltage."
Tyco's "Relay coil low side driver with coil suppression options":


Here is another good component:
http://www.diodes.com/datasheets/ZVN4206AV.pdf
Automotive Relay Drivers using the ZVN4206AV
http://www.diodes.com.tw/_files/prod...zetex/an10.pdf

The Tyco circuit is going to need more thought for the Canadian JK since don't want the lower duty cycle PWM Daytime Running Lights turning it on.

These things could be soldered on a relay socket - but if I'm going to do all this - why not 100% solid state circuit and get it over with? I've always known the correct answer is solid state switching but I was hoping to find a solution that the lay person can do.

Guess I am still looking for "good enough" rather than perfect. This is going to be a case of choosing the least of the various evils. To examine possible solutions is a harder core electronics engineering problem than I expected. I was hoping to come up with "Occam's razor" with just a diode and a fuse idea - but electricity is weird science sometimes.

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post #8 of 24 Old 01-24-2010, 10:37 AM
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Quote:
Originally Posted by Gavitron View Post
If I'm not mistaken, the shiny vertical metal box in the front driver's side quadrant of the engine bay is called the TIPM (Totally Integrated Power Module) and is essentially a bank of mosfets/SCRs/Transistors connected to the CanBus. When the canbus says "headlights on" this is the box that puts the pulsed DC out to the headlights...
Just to help keep things on track:

The TIPM is the black box directly in front of the battery. It has eight large connectors on the bottom of it to supply power to just about everything in the vehicle.

The metal box on the driver's side is the Powertrain Control Module (a.k.a. the main computer). It has four connectors.

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post #9 of 24 Old 01-24-2010, 12:08 PM
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Just to help keep things on track:

The TIPM is the black box directly in front of the battery. It has eight large connectors on the bottom of it to supply power to just about everything in the vehicle.

The metal box on the driver's side is the Powertrain Control Module (a.k.a. the main computer). It has four connectors.
Thanks for the clarification. But this begs two questions, if the metal box is the main computer, what is the metal box under my seat? And where is the control module for headlights/foglights then?
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post #10 of 24 Old 01-24-2010, 01:16 PM
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Thanks for the clarification. But this begs two questions, if the metal box is the main computer, what is the metal box under my seat? And where is the control module for headlights/foglights then?
The headlights, fog lights, and almost every other circuit in the JK is powered by the TIPM (that's why it has 8 connectors coming off of it).

I have no idea what metal box in under your seat. I have a 2007 and the FSM does not show a controller under the driver's seat. There is one on the 2007's under the passenger seat. It is a occupant classification system to control the passenger air bag. And there is a controller under the center console and it is the main airbag controller.

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post #11 of 24 Old 01-24-2010, 06:35 PM
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Originally Posted by chasinternet View Post
I hate the electrolytic solution - but that is due to my knowing more about capacitors than the PWM drivers and voltage protection in a Jeep. An electrolytic is going to fail - but it may take a few years which is why no one is complaining yet. If it just bursts, no biggie, but if it explodes taking out surrounding wiring - that gets expensive. Blown HID ballasts from constantly pulsing when turning off is expensive too.

[deleted]

"For single drivers the best compromise is probably an anti parallel low voltage (3…9V) Z-diode. A Zener diode in parallel to the driver would cause a varying voltage clamp across the relay coil during switch-off due to varying supply voltage."

[deleted]

These things could be soldered on a relay socket - but if I'm going to do all this - why not 100% solid state circuit and get it over with? I've always known the correct answer is solid state switching but I was hoping to find a solution that the lay person can do.
I basically did all of the above. Since I had the a socketed relay that came with KC Daylighters I added both a diode and capacitor across at the relay socket. I'm not a fan of the electrolytic capacitor either, but if it goes boom there is nothing around that should be damaged. (Although since it is under the hood it is exposed to much more extreme temperatures.) If it fails shorted the headlight circuit itself is fused and designed for high current. Plus my guess is the capacitor will quickly burn itself open after it fails closed.

I also have Zener diode on driver of the relay for the surge.

I lastly I have an additional diode where I tap into the high beam circuit as added protection. Don't know if this will do anything, but it's one more thing to burn through if the capacitor decides to blow up. The KC harness also came with a 1.5A blade fuse on this line as well.

I'll be the first to admit that it's not perfect, but it may be good enough. Given your scope readings the capacitor may not be required, but I decided to put it on since I was soldering the diode on my bench anyhow.

Regards, Tim

Last edited by Timbo2000; 01-24-2010 at 06:53 PM.
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post #12 of 24 Old 01-25-2010, 12:51 AM Thread Starter
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This was hard to find, not perfect for our purposes but getting there. This is probably what OEM manufacturers are using:

NUD3112
Integrated Relay, Inductive Load Driver
This device is used to switch inductive loads such as relays,solenoids incandescent lamps, and small DC motors without the need of a free−wheeling diode. The device integrates all necessary items such as the MOSFET switch, ESD protection, and Zener clamps. It accepts logic level inputs thus allowing it to be driven by a large variety of devices including logic gates, inverters, and microcontrollers.

Features
- Provides a Robust Driver Interface Between D.C. Relay Coil and Sensitive Logic Circuits
- Optimized to Switch Relays of 12 V Rail
- Capable of Driving Relay Coils Rated up to 6.0 W at 12 V
- Internal Zener Eliminates the Need of Free−Wheeling Diode
- Internal Zener Clamp Routes Induced Current to Ground for Quieter Systems Operation
- Low VDS(ON) Reduces System Current Drain

-Meets Load Dump and other Automotive Specs



These switch the low (ground) side of the relay coil. the "gate to source" voltage (what says microprocessor) is 12 volt which is cutting it too close but there are plenty of ways to limit the input voltage - no biggie. Also going to have to think about the Canadian Daytime Running Lights issue.

The 12 volt version is out of stock (3 weeks leadtime) but they have thousands of the 6V, 24V, and 60V at Digikey.com and Newark.com for 60 cents or less. There is a single 3 lead and dual 6 lead version. Unfortunately these are meant for surface mount PC boards but I can make them work.

If I was using the 24 or 60 volt the coil spec is lower (12 V at 150ma or 250ma using 1" sq. copper pcb).
http://www.onsemi.com/pub_link/Collateral/NUD3112-D.PDF
http://www.onsemi.com/pub_link/Collateral/NUD3124-D.PDF
http://www.onsemi.com/pub_link/Collateral/NUD3160-D.PDF

I've used digikey and newark for projects before - they have small pc boards, relay sockets, relays, etc. if I decide to try this.

Sooooo.... how does this idea look?

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post #13 of 24 Old 01-25-2010, 01:17 AM Thread Starter
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Given your scope readings the capacitor may not be required, but I decided to put it on since I was soldering the diode on my bench anyhow.
It may be required, I apparently lucked out with my relay being slow to drop out. Too much variance in relays to say what works for everyone.

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Originally Posted by Rednroll View Post
Now the tough part of using a mosfet is finding one that is easily available that can handle the current requirements of powering lights.
I noticed solid state relays for 12 VDC go up significantly in price after 5 amps but I can find many MOSFETs to handle higher currents reasonably priced. How difficult could it be? Have a car frame to attach a heat sink to and we already have DC.

I've never done a MOSFET switch circuit so I started reading - geesh its another quagmire trying to spec one. Need to have a voltage difference between what is used to switch and the load voltage is. So I thought voltage dividing the supply would work but then there are all these concerns about the usual inductance, resistance, capacitance that give MOSFETs a reputation of being finiky.

I still think its a better way but I'm too ignorant to know how to choose the proper MOSFET design. I notice there are now all sorts of MOSFETs types that I never heard of ten years ago but I didn't see anything that sounded like it was optimized for substituting 12V relays at higher currents.

We need a MOSFET engineer.

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post #14 of 24 Old 01-25-2010, 09:35 AM
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Rednroll, the headlights use dual filiment bulbs. One for high beam , one for low beam. That way the reflector/lens assembly can aim the light at different parts of the road.

A typical auxillary light is rated at 100 watts. Some are 55, some are 130. I have never seen any criteria specified about the voltage that light needed to attain that power. Is it 12, is it 13.8, or is it 14.x? I wonder about this because that will determine what the actual circuit current will be.

Yep, toggle switches to operate the lights.

The preferred load power source would be the battery. The preferred control power should come from a switched source such as the 12 power plug.

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post #15 of 24 Old 01-25-2010, 10:47 AM
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What I was getting at is that the 130 watt light may have been rated at 12 volts which would give it a current of 10.83 amps. Now if you take that same lamp and drive it with 14.4 volts, it will use 13 amps for an output of 187 watts.

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post #16 of 24 Old 01-25-2010, 11:16 AM
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Originally Posted by Rednroll View Post
I'll probably go to an automotive store and pick up a single aux light rated at 100 watts+ to test the circuit out.
Most use an H3 bulb. If you are just going play around on the bench, I'd just buy the lightbulb and save some cash. Of course since I have 130W lights I'd suggest a 130W H3.

But thanks for helping us all out.

Regards, Tim
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post #17 of 24 Old 01-25-2010, 02:45 PM Thread Starter
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Rednroll thanks. I will restate the problem I was attempting to solve which is different than Alter Ego. The 12 volt power plugs in the cab are not PWM.

The traditional way of turning on auxillary lights is a new switch in the cab. New wiring for the lights and relay connected directly to the battery, trip the relay coil using the switch connected to the back of power plug outlet in the cab (or switch the ground side of the relay coil with the plus side of the coil fuse connected to battery/ light supply line). This has no problems with relays that I am aware of - I use it for my windshield mount HID lights. HIDs are typically 35 watts. I have seen the ballast draw 5 amps under a second to start then settle to under 3 amps per light.

Solid state would be more reliable than relays for the traditional method but it is not the problem I am looking at. (EDIT: halogen lamps have an inrush current of 20A to 100A - see http://www.micrel.com/_PDF/App-Notes/an-3.pdf)

Adding driving lights is an issue. The law in some states require that driving lights be switched ONLY by the high beam switch. In California, if I add a separate switch in the cab, it violates the law. This is why I tapped the high beam line going to the stock headlights to activate the relays for my driving lights. The driving lights relay is wired directly to the battery, I just trigger the coil off the stock PWM high beam line.

The Jeep uses PWM voltage which is problematic hooking to a relay coil both for the relay and the system. In California, if you want driving lights, you have to tap the high beams, there is no other legal way. In Canada, they have an additional challenge, Daytime Running Lights are mandatory so the 2.6V, 18.5% DRL is on until you switch on the high beams. This means the solid state switch has to ignore the lower PWM.

Automotive relays I see for sale have 72 to 680 ohm coils - so 200ma would be the high side.

The low/high beam oscilloscope is identical (Jeep headlight connector is 3 pins - low beam, high beam, return). If you want me to send the output or new tests let me know. I also have a variety of lights and equipment here.

EDIT: The On Semiconductor device I posted above is almost perfect for interfacing an electromechanical relay and protecting the Jeep system - the issues I see are it is surface mount instead of leaded (which makes it difficult to use), have to limit the input from the PWM high beam tap, and the power handling specs are a bit too close for comfort but should be ok. The Canadian DRL issue would probably have to be solved by experimentation, maybe a simple filter will limit both the high beam PWM and eliminate the DRL PWM triggering the relay. If doing solid state switching - then the triggering can also be controlled.

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Last edited by chasinternet; 01-25-2010 at 04:25 PM.
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post #18 of 24 Old 01-26-2010, 04:13 PM
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Quote:
Originally Posted by chasinternet View Post
In California, if I add a separate switch in the cab, it violates the law.
As an individual you can wire up switches however you please. If you run more than four filaments in a forward direction (excluding turn signal/marker lamps) at one time it violates the law.

California Vehicle Code States:
24405. (a) Not more than four lamps of the following types showing
to the front of a vehicle may be lighted at any one time:
(1) Headlamps.
(2) Auxiliary driving or passing lamps.
(3) Fog lamps.
(4) Warning lamps.
(5) Spot lamps.
(6) Gaseous discharge lamps specified in Section 25258.
(b) For the purpose of this section each pair of a dual headlamp
system shall be considered as one lamp.
(c) Subdivision (a) does not apply to any authorized emergency
vehicle.

California Vehicle Code further states:
24406. Except as otherwise provided, the headlamps, or other
auxiliary driving lamps, or a combination thereof, on a motor vehicle
during darkness shall be so arranged that the driver may select at
will between distributions of light projected to different
elevations, and the lamps may, in addition, be so arranged that the
selection can be made automatically.
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post #19 of 24 Old 01-26-2010, 05:59 PM Thread Starter
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24402. (a) Any motor vehicle may be equipped with not to exceed two auxiliary driving lamps mounted on the front at a height of not less than 16 inches nor more than 42 inches. Driving lamps are lamps designed for supplementing the upper beam from headlamps and may not be lighted with the lower beam.

Yes, people do get the hassle ticket... since I'm middle aged driving a Jeep I doubt I am going to get hassled.... but if I was 20 something years old again driving a modified vehicle at an excessive rate of speed - well, being in Orange County, you know how my introduction to the CHP went... even the worn windshield wipers...

My son borrows my Jeep sometimes.

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post #20 of 24 Old 01-26-2010, 06:32 PM
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Quote:
Originally Posted by chasinternet View Post
24402. (a) Any motor vehicle may be equipped with not to exceed two auxiliary driving lamps mounted on the front at a height of not less than 16 inches nor more than 42 inches. Driving lamps are lamps designed for supplementing the upper beam from headlamps and may not be lighted with the lower beam.
I'm still not clear why they couldn't still be switched. You'd need the condition of the high beams on AND the cab switch on to illuminate the beams. You still have choice if you want the aux lights on or off with the high beam circuit. That's the way I've wired mine.

Regards, Tim
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post #21 of 24 Old 01-26-2010, 06:38 PM
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Originally Posted by Timbo2000 View Post
I'm still not clear why they couldn't still be switched. You'd need the condition of the high beams on AND the cab switch on to illuminate the beams. You still have choice if you want the aux lights on or off with the high beam circuit. That's the way I've wired mine.

Regards, Tim
I think what he's saying is that he doesn't trust his kid. The law says they may not be lighted. There's no requirement about how they're switched.
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I think what he's saying is that he doesn't trust his kid. The law says they may not be lighted. There's no requirement about how they're switched.
LOL - cop? .... sure, could probably beat the ticket anyway but if a cop wants to hassle then they hassle.... and you get a lot more hassle when you're young was my point with my son... if I didn't trust him a whole bunch he'd never get the Jeep.

I asked a CHP about it after reading about a ticket... he said he wouldn't give it but others have read it as required... I figure its not worth the potential hassle and would be a lot more convenient anyway (especially having to dim for on coming traffic)... what I didn't realize until recently was relays throw high voltage spikes back at PWM system when they are turned off.

EDIT: I just remembered - if it was switched on by a cab switch then it is an off-road light not a driving light and therefore must be covered. He said it was up to the officer and with a cab switch I could not prove it was not an uncovered off-road light, therefore as soon as high beams go off - its illegal. (BTW, "may not be lighted" can be interpreted to mean we don't have the choice)

Seems like it should be simple enough to solve, I think I've found a solution by copying the On Semiconductor circuit if I decide what Zener diodes to get. I have to run it by an electronics engineer.

Thread is getting sidetracked - point was be able to use PWM to provide relay switching originally. People are using capacitors to be able to use PWM for a wide variety of reasons but I haven't taken a survey.

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post #23 of 24 Old 01-27-2010, 01:55 AM Thread Starter
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Originally Posted by Rednroll View Post
Sorry, it's been a busy hectic week this week. So my attention span is a little foggy of what you just wrote....but what I think you said is that you need a circuit that triggers off the PWM from the high beams, and there's a separate wire that connects to the head lights which carries the low beam PWM and I shouldn't have to worry about that. So I'm assuming that when you switch to low beams that the high beam PWM goes to zero volts.
No problem, I have a ton of work to do also but having an attitude problem this last week.... and yes I write too much.

You are correct. High beam goes to zero volts for me, however, some people here have Daytime Running Lights (everyone in Canada also) which use the high beam line at 2.6 Volts (18.5% duty cycle) while the headlights are not in low/high beam.

I can switch the JK to DRL mode using my AEV Procal - that's how I know what the DRL duty cycle is.

The devices I posted schematics of provide protection from electromechanical relays. Since the On Semiconductor device is a tiny surface mount package - I could try to copy the circuit using discrete devices with leads soldered together for a electromechanical relay solution. Thinking about trying bidirectional transient voltage suppression (TVS) diodes instead of the zeners.

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post #24 of 24 Old 01-27-2010, 08:21 PM Thread Starter
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Yup - comparator is what I saw too. For solid state relays I don't know if there is another way, they react fast.

I expect filtering or something might work with the electromechanical relay but the temperature variations in the engine compartment might throw it off. I was thinking about getting the ZVN4206AV leaded fet I mentioned above, some zeners and TVS diodes and see what the DRL does.

My original hope, however, was to find something users could put together without making a printed circuit board. Unless you're planning a cottage industry offering an assembled device (would be fine by me) its going to become something only a select few of us can do.

Maybe best course is figure out a design you are comfortable with and we'll worry about assembly challenges later. Maybe a USA version and then a seperate DRL version.

As far as I know, the reduced duty cycle high beam DRL is a Canada issue and a few USA users run it - if they buy an AEV Procal they can flip the DRL to low beam line instead of high beam line. Don't know if their laws specifiy or not which line. (Jeep fully activates the low beams for the European market DRL.)

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Last edited by chasinternet; 01-27-2010 at 08:28 PM.
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