ATV project (need a little help)

[MrTodds]

Re: ATV project

I think the NiMH pack might work better than an electrolytic capacitor (I assume that’s what you are using) at damping the high spikes. The NiMH pack will exponentially increase the load on the system when it sees voltages above 14v. The cap damps the voltage more linearly within its operating voltage.

If you get a GPS, don't get a Magellan they can't take the vibration. I turned two of them into baby rattles! A Garmin eTrex can take the punishment.

I ride in the Sierra’s, Baja, Owens Valley (dual sport) and a local riding park. From the pics it looks like you enjoy the dunes. I have put on the paddle tire and ridden Pismo, lots of fun!

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
MrTodds said:
I think the NiMH pack might work better than an electrolytic capacitor (I assume that’s what you are using) at damping the high spikes. The NiMH pack will exponentially increase the load on the system when it sees voltages above 14v. The cap damps the voltage more linearly within its operating voltage.

If you get a GPS, don't get a Magellan they can't take the vibration. I turned two of them into baby rattles! A Garmin eTrex can take the punishment.

I ride in the Sierra’s, Baja, Owens Valley (dual sport) and a local riding park. From the pics it looks like you enjoy the dunes. I have put on the paddle tire and ridden Pismo, lots of fun!

[/ QUOTE ]

The only thing that gets me about a voltage spike is that I had run the Cyan LED's for a few rides before and these shorted out right away and my friend has been using them fine on his 3 wheeler ever since. I'm now thinking about simply re-creating the circuit and trying again. I don't see how an LM317T would not be tuff enough for this job. Perhaps the LM317HVT reacts differently? I guess I'll just give it another shot since it worked before.

I had an EE engineer help me plan this in the first place. it's not an automotive grade part but the circuit is not the primary regulator either, I already bought an expensive one to do that so I could run my headlights tailllight etc and have never blow anything. See what I'm saying? Then again I don't know much, im a comp sci major not an electrical engineer.

But the NIMH idea seems like it would get more complex, switches needed etc, although I would eventualy like to move to something like this as a next step (so I can leave it on as a saftey light at teh top of a dune or a competition hill at night). but someone correct me if im wrong? Im not relying on the LM317T to regulate raw voltage, there is a voltage regulator (large one) that regulates my headlights etc, and from that it is run into my circuit, thats why I say the 14.4V is pretty constant peak voltage, even if it peakes over that should not get past 30 some odd volts that the circuit should be able to handle...Does this sound right to anyone?

Im guessing instead that it was a freak incident or a short in my circuit as suggested. Im going to rebuild it from ground up I guess /ubbthreads/images/graemlins/frown.gif The guy with all the equipment did not want to test it for me.

 

[IsaacHayes]

Re: ATV project

which luxeons fried?
Keep in mind red luxeons have a positive heatsink slug. So they have to be isolated from neg connection on the heatsink. Also they have a lower voltage forward... ~2.xx volts or so...

 

[B@rt]

Re: ATV project

Nice pics, but could you shrink them down a bit? They make it necessary to scroll...

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
IsaacHayes said:
which luxeons fried?
Keep in mind red luxeons have a positive heatsink slug. So they have to be isolated from neg connection on the heatsink. Also they have a lower voltage forward... ~2.xx volts or so...

[/ QUOTE ]

Now thats usefull stuff! so if the HS grounded into the frame of the bike it would toast the LED?

The pics look small on my screen heh. I can try to shrink them later if I have time...Right now everything is a rush...

So you think the HS grounded into the fame would have toasted the LED? The Red one fried, and it was the second one in the series too.

I was just about to junk my circuit for parts so if you could verify that I would really appreciate it! Might save me the time and money of rebuilding a perfectly good circuit!

Also is there a way I could test this current limiting circuit without using a start-O to compleat the circuit? if so please let me know! Thanks!

The Reds are the Star-O's I just epoxied HS's to the back of them, aren't they automatically isolated by the PCB they come on?

I tested it on my volt meter and the HS is definately Positive,so if this HS contacts the frame on the bike and becomes grounded would the LED fry or just not light up? This could be the entire problem. When I first tested the HS it was not mounted to the frame...Let me know!

THANKS SO MUCH!

 

[Lucien]

Re: ATV project

AFIK all 1W Luxeon stars have their slugs electrically isolated from the aluminium star by the PCB they're sitting on.
I'd think that if your bike frame forms ground, and there was no electrical isolation of the slug, there would have been a short from the positive output of the 317 regulator to ground via the LS. I have no idea what this would do to the LS however...

About the DownBoy vs the 317 regulator circuit:

The DownBoy (DB) falls under the category of switching regulators - it converts power in to power out (minus the efficiency loss). Given power = voltage across device x current through it, it is possible to take in high voltage and low current, and output lower voltage at higher current.
The 317 acts as a linear regulator - it draws in the same amount of current as it puts out. Whatever voltage that doesn't fall across your load device (in this case the LS) falls across the 317, and the resultant power is dissapated as heat.

For a very high input voltage compared to the output, this would be quite inefficient. eg if your input voltage was twice what the load device needed, the entire circuit would only be 50% efficient.

Sorry for the slow reply, but I've been busy with work...

 

[Justintoxicated]

Re: ATV project

yea but tis an unlimited power source so I don't need to be efficient. The LM317's never heated up much, but I heatsinksed them anyways.

My main concern now is wether or not to re-build the circuit. I'd have to use a couple different downboys so Im talking an extra $50 or so...thats 5x more expensive, and there is no need for me to worry about efficient.

I need to find out if grounding the HS would have fried the star (but im very doubtful), or if there was just a short on my circuit. Or if it was due to using an LM317HVT instead of an LM317T. Sounds to me like Im just going to end up trial and error untill the starts stop frying. /ubbthreads/images/graemlins/frown.gif This sucks


which one of these 2 fried my star..How can I put a load on the circuit so i can measure the amps without attaching a star?

Thanks for your replies.

How do the 3 watt blues differ? I have the HS mounted to the frame also?

 

[gadget_lover]

Re: ATV project

I think that IsaacHayes may have pointed to a problem. The red luxeon has a Vf in the 2 volt area. If you have set the LM317HVT output above that it will cause the LED to burn out. Thsi would account for the one LED burning out while the other (a different color) was OK. I scanned this thread quickly, but did not see where you were limiting the voltage to the LED.

It would be a good idea to check the voltage drop across the LED to make sure it's within the manufacturer's specs.

Wire wound resistors of the same resistance as your LED would be appropriate for testing your circuit. They DO get hot.

Daniel

 

[IsaacHayes]

Re: ATV project

Download the Lumileds .pdf's on luxeons and check out the vF's of the different colors.

The Red, Red-Orange, & Amber luxeons have a much lower Vf than the blue/cyan/royalblue/green luxeons do. So if you feed them the same voltage as a blue luxeon takes, then they will draw a lot more current and fry.

The docs say you must isolate the heatsink slug from voltage as they aren't neutral. From experience here people find the blues/greens/etc are neg slug, and the reds/ambers/r/o/etc are postive on the slug...

 

[Justintoxicated]

Re: ATV project

For sure im not over feeding voltage to them.

The Vf should be PERFECT for each LED im NOT limiting voltage, I am limiting current. The blues are being fed 1 amp, the reds are being fed 350ma. The Vf of the lights vary slightly from what I hear but this should allow them to run at their proper Vf reguardless (if you give a light 350ma it will run at its proper Vf even if the 2 LEDs have slightly different Vfs as long as they are both designed for 350ma)...That is not the problem, this shoudl allow them to run PERFECT.

What concerns me now is that the HS's are epoxied to the back of the Luxeons with Artic Silver. Im not sure atric alumina would be a good solution either as the HS may still touch the PCB backing ithe luxeon stars.

The trouble is this, im using aluminum brackets to attach the Heatsinks to the frame, the frame of the bike is gound. This would indicate that there is a direct short right? I tested it at low voltage with just the reds and noticed the voltage from the back of the luxeons HS continues into the frame.

So basicaly im leaking voltage into the Frame of the bike, which is also the bikes gound. I have no ability to make the mounts out of plastic either...So now Im kinda stuck as to how to insulate the Brackets from the frame when theya re metal... Any ideas? Or do you guys think should not be problem anyways?

Also in order to check the current the circuit is producing I need to run something off it, what can I use to simulate a star-O? so I can check the current to make sure its 350ma?

The slug is what part on the Star-O? the bottem? I do not give them any voltage, but they are connected to the frame, so it is sorta like all of the Heatsinks are connected together through the frame on the bike. This is wrong correct?

 

[IsaacHayes]

Re: ATV project

get some teflon or plastic or whatever washer spacers or rubber washer spacers to stand off the brackets from the bolts/frame. You can measure current the LS are drawing (assuming they are working) by putting a multi meter in series with them and measuring current draw...

 

[gadget_lover]

Re: ATV project

[ QUOTE ]
Justintoxicated said:
For sure im not over feeding voltage to them.

The Vf should be PERFECT for each LED im NOT limiting voltage, I am limiting current. The blues are being fed 1 amp, the reds are being fed 350ma. The Vf of the lights vary slightly from what I hear but this should allow them to run at their proper Vf reguardless (if you give a light 350ma it will run at its proper Vf even if the 2 LEDs have slightly different Vfs as long as they are both designed for 350ma)...That is not the problem, this shoudl allow them to run PERFECT.



[/ QUOTE ]

Someone will correct me if I'm wrong. /ubbthreads/images/graemlins/smile.gif You can check the voltage at the LED easily enough with a volt meter. If the current is constant at 350ma but the voltage is above the correct range, it's using a lot more power than at would at the correct voltage. A zener diode will shunt the extra voltage away from the LED.

An LED is a semiconductor. If the voltage is too high it will break down the junction.

I could be wrong, but don't think so.

Daniel

 

[Justintoxicated]

Re: ATV project

well the LED's should handle any voltage from a source if the current is regulated, they can only produce so much of a Vf. I have read this by others. As long as the CURRENT is never above 350ma the LED can only produce its proper Vf. Or the other way around to say it is that the LEDs can be run on a battery of any current as long as the voltage is regulated; if you regulate the voltage, the LED can only draw 350ma...

Basicaly you will be fine if you regulate the current or the voltage, as long as one is regulated the other will be a resultant.

Im jsut curious about the damages of linking the HS's together through the bikes frame allt he LEd's are mounted by the HeatSink, and they are therefor connected through the frame. I like the idea of plastic spacers, but at this point I am not sure how it would be possible.

I mean, If I put a spacer in the hole where the bolt goes through the bracket then how do I sung the spacer to the bracket? Just curios if you had something in mind.

Thanks again,
JI

 

[gadget_lover]

Re: ATV project

There are plastic standoffs designed for just such applications. The standoff looks like a thinwall plastic tube. An insulating washer is frequently used on both ends of the standoff. The tube is the same length as the thickness of the metal it penetrates.

The washers keep the nut and the body of your light from touching the mounting surface. The tube keeps the screw (or stud) from touching the mounting surface.

The Electronics Forum. Batteries Included is a good place for information regarding power supplies.

Daniel

 

[IsaacHayes]

Re: ATV project

Ok, like this:
bolt= ------l, spacer= ||, braket= +++,
ATV frame------||-+++-||-l

Not sure if that helps at all, but basicly the bolt will screw into the ATV frame with a washer on each side of the braket. So the bolt won't touch the braket, as it will be centered in the hole of the bracket by the spacers. The head of the bolt will push down on one washer, and the bracket will push down on the washer on the other side onto the atv frame.

Perhaps imagine using plastic pipe as an example insetad of washers. Some stiff plastic tubing would work if cut in a short length. You might have to drill out the holes of the brakets larger so the bolt doesn't touch the braket.

EDIT: I see Daniel is thinking along the same lines.

Here is another idea that would be even easier. Get some rubber gromments, like what you'd use to install in a hole after you drilled a hole in the firewall of a car to run a wire through. Drill out a hole to fit the gromment in the braket, install it, and then put the bolt through and tighten down. EASY! /ubbthreads/images/graemlins/thumbsup.gif

a gromment looks like this where the middle is smaller and the fatter top and bottom sticks out the sides of the braket after you push it in:
+++++
.----.
+++++

 

[Justintoxicated]

Re: ATV project

thanks guys, i think ill look for some standoffs or some gromits tomarrow or soon at least at home depot.

I apreciate all the help..

I ripped the circuit to pieces after it fried my cyan..Burned it to hell too with my solder gun /ubbthreads/images/graemlins/smile.gif

Managed to spare the Capacitor and the heatsinks on the LM317T and HVT and also my bullet connectors and wire...I broke the rest of the compnents apart to see what was in them lol. + I was angry at them anyways /ubbthreads/images/graemlins/smile.gif

 

[IsaacHayes]

Re: ATV project

It's fun to break stuff /ubbthreads/images/graemlins/smile.gif
If it fried then something might be wrong with the design. Or a voltage spike might have killed it?

Also, if they are all hooked up in series, then won't that end up needing a voltage higher than what the atv can supply? Not sure how many luxeons you had on there...

 

[Justintoxicated]

Re: ATV project

yea it was fun. Its not fun re-buildign them though..The design is fine. As I said I have run one before without any issues jsut using a different resistor value (1 watt 3.9 OHM) this time I felt more confident and used 4 1/2 watt 3.7 OHMS to create a 1 watt 3.7 OHM resistor to give it a little more juice, but not and extra 500ma worth! It seems the voltage regulator was defective and fried my lights /ubbthreads/images/graemlins/frown.gif I got it out of the package from an electronics surplus and it looked pretty old...It also did not measure out as 1.25 ohm but I had never tested my other ones in this way so I thoguht it might be working anyways...

no more getting discount components!

Since im only running 2 lights on each LM317 there will be plenty of power for them. I could probably run 4 at almost full power (1 watts) the 2 3 watts is pushing it but it works fine since I have 14.4 Volts...

I need to find those rubber gromits, then all the problems will be solved. I may just use a 3.9 ohm 1 watt resistor this time to save board space, I just wanted my Reds to appear nearly as bright as my friends Cyans.. they are rated 3 lumens less, so I figured I could make some of the difference up by driving these a little brighter...

I don't think the isolation is what friend my lights but I guess I'll try to isolate them anyways, even though it will be one of the most difficult parts of the project.

I already have a new project in mind. I need a nice bright side emitter for my whip light, one that can run on batteries that recharge as I ride. It sounds really complext to me so I'll save it for another post, but I need to be able to turn on an LED high above my head so people do not run me over with there big giant dune Buggys. When my bike is off and your out in the middle of the desert with no moon its quite dark (especially on the side of a dune) no1 can see you and there are accidnets every year. ATVs and bikes always loose to duen buggies and trucks.. Also might come in handy when I stop to let the bike cool down and drink a beer /ubbthreads/images/graemlins/smile.gif

I'll post again later, im not really sure how bad I need to isolate the blues, im getting impatient on waiting for bio degradable coolant (engine Ice)..

 

[IsaacHayes]

Re: ATV project

Reds don't do good overdriven. 350-400ma is what you should shoot for. Why? because as heat goes up, their output drops signifacantly. They put out a ton of lumens anyways from the start for what little power they get.

The blues and cyans will need to be driven harder usualy to match the reds. If you have LuxIII's I'd drive them at like 600-700ma and you should be good. See the other thread I posted there too..

 

[Justintoxicated]

Re: ATV project

[ QUOTE ]
IsaacHayes said:
Reds don't do good overdriven. 350-400ma is what you should shoot for. Why? because as heat goes up, their output drops signifacantly. They put out a ton of lumens anyways from the start for what little power they get.

The blues and cyans will need to be driven harder usualy to match the reds. If you have LuxIII's I'd drive them at like 600-700ma and you should be good. See the other thread I posted there too..

[/ QUOTE ]

Im driving the 3 watt blues at 1 amp, they are heatsunk and usualy the bike will be moving and thus blowing air over them also. The reds I was plannign to run at spec or close to 350ma...My friends Cyans were driven at 320ma and people riding behind me were already complaining /ubbthreads/images/graemlins/smile.gif

The Cyans I beleive are still actually brighter than the Reds (low domes) the high domes are supposed to be brighter 40 something lumens vs 27 for the low domes and cyans are 30.