The best bad idea I've had today

[Oakwright]

I just had a flash of inspiration that is a horribly terrible awesome idea!

So, it's simple really. It is based on three simple facts, that when combined, are terrible and awesome:

Drilling holes in the sides of motors makes them vent better, helps them dry out.
Hall sensors inside the motor make three different signal wires turn on and off as the wheel spins.
LED lights can be run at very low voltage.

I mean think about this for a second... Stick a few LEDs inside of a hub, wired to the hall signal wires. As the wheel spins, it will turn them on and off. They would be visible through the holes in the motor plates. Not only would this increase your visibility by having some nice strobing LEDs on the side of your bike, but it would also just look pretty awesome. And gaudy.

Right now my motor is torn apart since I'm doing some repairs on it, so it would be a perfect time to add this horribly gaudy addition... I just might do this.

 

[liveforphysics]

It should work. Neat idea. Make sure to have a current limiting resistor inline or it might clamp the hall output too low.

 

[spinningmagnets]

Also, if the bike starts running odd, you could check if all three LEDs are firing, as part of the diagnostics process? (I don't know if that would work, but theres gotta be a way, right? like the LED is on the leg leaving the hall so it wouldn't light up if it had shorted?)...

 

[Oakwright]

I know right? It's like having a built in hall tester too!

 

[Philistine]

You would have to have a subwoofer attached to the bike to put out a beat in conjunction with each or every other switching hall. If you took enough pingers and attached a smoke machine you could become a mobile DJ....

 

[Oakwright]

Okay, my wife made me stop and think about this rationally. She's the logical one in the relationship.

There are 46 magnets (assuming my counting skills are functioning today), so there should be 23 blinks per rotation (one magnet turns the light on, the next magnet turns it off).

Referencing this other thread about RPM of a 26 inch tire: http://endless-sphere.com/forums/viewtopic.php?f=28&t=16114

So, 1 mph = 12.93 rpm. That would equate to 297 blinks per minute, or nearly 5 blinks per second.

Depending on who you are arguing with, the human eye can detect between 24 and 100 frames per second. So somewhere between 4 mph and 20 mph you won't be able to tell one blink from another. Since people won't be staring at your wheel intently, I'm guessing the blink rate has to be much slower to be detectable.

If you have three LEDs rigged (one to each hall), then there will be three times as much blinking in there, which will basically mud the blink pattern up even more. Also, one LED will be on at all times since at any given time one of the halls will always be "lit". So it won't even be turning off and on, it will just be rising and falling in intensity (or if using different colors it will just color shift instead of strobing).

Keep in mind also that there is a rise and fall time involved with LEDs, so that will also mud up the blinking a bit more too.


But... there is still hope. If you have holes drilled in your plate, and an LED on the stator inside, then each time a hole passes in front of the LED it will basically strobe it. So you don't really need to hook it to the halls at all. Just stick an always on LED in there and it will strobe or as fast as you want depending on how many holes you drilled in your plate. If one hole, 1 blink per rotation. if 6, then 6 blinks per rotation. At 1 mph with one hole, that's .2 blinks per second. at 20 mph with 6 holes, you have 48 blinks per second.

So bad news is it isn't really worthwhile to rig up LED's to your hall sensors. Good news is that sticking an LED inside the motor would still look cool, since you could vary it between .2 and 48 blinks per second depending on amount of holes and and speed.

 

[ZOMGVTEK]

While we are talking about bad ideas...

Is there any reason why nobody runs a wireless temp probe in the motor? Most of the senders run off button cells, typically 3-6V, so I would imagine the controller can drive that. With some ventilation holes in the motor, it should probably work the 2' it needs to go, right?

Anything serious wrong with this logic? Running little wires through the axle is a hassle, and little wires are prone to breaking. As long as it updates every 10 seconds or so, it sounds like a superior option to me.

http://www.ebay.com/itm/140593510533?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_693wt_1180

Something like this will probably get the job done... Just need to crack it open and jam the PCB in the motor.

 

[Oakwright]

I can't see why you couldn't hook up a temperature sensor inside the motor. I think you would have to wire it so the transmitter is outside of the hub though, since I'm not sure how it would behave with a ring of magnets spinning around it. But still, I can't see why you can't put a sensor in there with a wire coming out the axle (besides the fact that running wires through the axle looks like a pain).

 

[John in CR]

I know right? It's like having a built in hall tester too!

True, but it's also like installing a bunch of new points of failure. Properly placed and size ventilation holes would put the LEDs viewable from only very narrow angles anyway. It would be cool to see, so go ahead an go for it, but forgive me if I'd have to pass even if someone else did the work.

John

 

[Oakwright]

True, but it's also like installing a bunch of new points of failure.

True...

Properly placed and size ventilation holes would put the LEDs viewable from only very narrow angles anyway.

Unless you shined up the inside of the hub enough to function as a mirror... or put mirrors inside... like an inside out disco ball! Yeah okay maybe not.

 

[sn0wchyld]

I've just done similar, putting leds inside the hub but running off 12v dc rather than strobing. the silvery metal of the side cover works well enough as a mirror, and the motor glows red out of the holes!! Ill post a pic/vid asap. It'd be interesting to set up a strobe that turns the leds on in time with the speed of rotation, to make it look like the holes aren't moving at all, or are even rotating slowly backwards!!

 

[dnmun]

the 5V from the controller would provide enuff current to run some leds inside the hub. you could not take power off the hall sensor lines, but you could use the 5V to supply current for an op amp that would be able to detect the state of the hall sensor and switch the mosfet to turn the led on and off, but then the led would be switching really fast too.

 

[amberwolf]

If you used a counter chip instead of an op-amp, clocked by a hall signal, then the counter could be used as a frequency divider. There's a number of 4000-series chips and 74xx-series chips that would work well for this, whose outputs could directly sink the LED current from 5V, with a small current-limiting resistor in series with the LED.

 

[Lessss]

I wonder if there are any leds that change colour depending on their operating environment.

 

[MattyCiii]

I wonder if there are any leds that change colour depending on their operating environment.

Just use an RGB LED: http://www.adafruit.com/products/315

 

[MattyCiii]

True, but it's also like installing a bunch of new points of failure.

Notwithstanding any results we see from sn0wchyld's efforts, I think it's simply not worthwhile to put the LEDs inside the hub motor unless they pull double-duty as both bling and as hall diagnostics.

Otherwise, use something like http://www.monkeylectric.com/ and run it independently off its own batteries. I have/use one, like it a lot, it's built real tough and draws low power.

Edit: An arduino (one of the mini ones, like Ardweeny, $10) plus temp probe plus RGB LEDs can diagnose & display several things... like maybe make the motor glow a gradient from cool blue to red hot, instead of or in addition to monitoring halls.

 

[amberwolf]

Edit: An arduino (one of the mini ones, like Ardweeny, $10) plus temp probe plus RGB LEDs can diagnose & display several things... like maybe make the motor glow a gradient from cool blue to red hot, instead of or in addition to monitoring halls.

So you could take something like the SpokePOV from Adafruit and wire it up to do that double duty, with a little reprogramming.

Heck, if you install it outside the motor like normal, and use wireless transmission to it (which was discussed on the Adafruit forums, IIRC), you could use it to display the motor temperature in the wheel, if you liked, though you yourself coudln't read it while riding. :lol: Alternately have it display the temperature as a brightness thing, where you light up more LEDs the hotter it gets. Could do that for more power applied, too--"rev" the throttle and it lights more LEDs like an audio power meter bargraph--not for more RPM but for more current (or more wattage).

 

[BATFINK]

It might attract unwanted attention to your motor.

Sent using Endless-Sphere Mobile app

 

[kfong]

Yep, I think the LEDs would look like they were on all the time and the added load to the signals might not be so good. Your other idea of a temp sensor does have a good use. Look up POV spokes. Power can be supplied by the hall wires and temps can be displayed by 8 LEDs turning on a set intervals. Cool for those who have vent holes, just like those virtual clocks you see on a stick. Makes me want to pull out my POV project, but I haven't gone to vented covers yet.

Just notice AW mentioning the same idea.

 

[dnmun]

i repeat. you cannot drive the leds from the hall sensor wires. you can use an op amp with a high input resistance to detect the state, but if you put an led on the hall sensor wire, it will just sink current into the led and controller would think all three phase were turned on. but the red wire, the 5V, would provide enuff current for the leds without affecting the function of the hall sensors.
if there were holes in the cover then the led would appear to flash on and off, but at a high rate depending on the number of holes.

 

[sn0wchyld]

True, but it's also like installing a bunch of new points of failure.

Notwithstanding any results we see from sn0wchyld's efforts, I think it's simply not worthwhile to put the LEDs inside the hub motor unless they pull double-duty as both bling and as hall diagnostics.

Otherwise, use something like http://www.monkeylectric.com/ and run it independently off its own batteries. I have/use one, like it a lot, it's built real tough and draws low power.

Edit: An arduino (one of the mini ones, like Ardweeny, $10) plus temp probe plus RGB LEDs can diagnose & display several things... like maybe make the motor glow a gradient from cool blue to red hot, instead of or in addition to monitoring halls.

yea mine really serve no other purpose other than bling and the ability to check the state of my added internals (fans and the like). They handle the heat fine though.

Now that I think about it I could quite easily wire it up to the LED output of my temp probe (that lights up when in 'alarm' state), so if the probes allarm goes off, it will light up the hub with a flashing red LED. You could mount everything internally too, as the temp monitor can run of 5v and is about the size of a box of matches. It also has an audible alarm.

I remember reading somewhere that this unit draws 500ma in its alarm state, can the hall +5v line handle this without affecting the halls function?

 

[kfong]

The 5 volt line usually comes off of the same supply that powers up the rest of the 5 volt system. This is usually a linear regulator not being pushed too hard. .5amp seems a lot too ask of it. Maybe you could find a more efficient buzzer to use.

 

[chuckufarley]

I have a Blue LED fan cooling my contoller.....dude.....I may just try this.

 

[sn0wchyld]

lighting coming out of the motor does look pretty sweet, I tried getting some video on the gopro but it came out shit, ill try again soon. blue would look rather 'cool' too 8) .

 

[shock]

Just run some 24g magnet wire through the axle and attach a couple LED's to it if you want lights in there. Personally I would not start messing with items necessary for the motor to run properly-- that's just asking for trouble. I'm not sure how much a controller is going to like seeing a bunch of diodes on the hall sensor circuit. To each their own, but I'm leaning on this is a bad idea.