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Monday, February 16, 2009

Minor Improvements, Still In Progress

Since not enough of it is done yet to see how it works in an image, this is a quick MSPaint of how the chain deflector/guide will work.

The dark blue/purple across the top is the Magna's bottom bracket and chainstays, with the green bar along the bottom edge of that being the kickstand mounting plate on the Magna. The peach ring around the BB is the pedal chainring, and the gray bar diagonal to that is the crank. The white plate is the mounting plate for the CDG, and the red outlined portion is the pivot plate the blue skatewheel is attached thru, via the bottom green axle with bearings. The gray squiggle is a spring, to pull the wheel downward against the orange chain's tension. The top green dot is the pivot bolt for the pivot plate to swivel against. The gray arc is where the green axle can swivel thru. The spring is attached to a pin welded to the main mounting plate in the lower left corner, up to the axle bolt on the inside of the mounting plate (other side from where the wheel is). I have several possible springs to fit in that space, depending on the tension required.

The need for the swivel is caused by this being the primary throttle control. As I pedal, the more tension in the top of the chainline (such as when starting up from a stop, or uphill), the more torque I am having to apply to the system with my legs to do work, and the more the wheel will be forced upwards along the arc, against the spring's pull. The pivot plate will be attached to a throttle control (at this point, a magnet that will affect a Hall-effect sensor), so that as it swings farther upward, it commands more and more power to the motor. If there is no tension on it at all (such as when I am not pedalling, or when the motor or a downhill section is forcing the wheels faster than the pedal chainline), then it swings all the way down and the motor gets no power.

Since there may be a need at some point for me to use the motor either without pedalling or more likely to use it to go faster than I *can* pedal in a particular situation, or for a burst of emergency speed to avoid some situation, the cable from the Honda Spree's throttle assembly will attach to this in a way to pull the pivot plate up just like the chain would when under tension, giving me manual control of the throttle as well, without complicating the electronics by having to merge two different inputs. The Honda throttlegrip is already designed to use a cable to pull a fuel throttle valve in the engine, so all I am doing is using that same cable to pull the pivot plate instead. The original cable should easily reach this point on the frame from the bars, and if for some reason it does not, I have plenty of other cables that will.

This also allows me to not have to rig up an electronic throttle to the mechanical grip on the bars themselves, leaving me a bit less wiring to do up there. There is quite a bit already, with just the built-in Honda grip controls:

  • twin brake-light-switches
  • turn signal switch
  • headlight bright/dim switch
  • run/stop/run knob
  • horn button
plus if I use the Honda's mechanical speedometer/odometer/etc box:
  • backlight
  • turn signal on light
  • highbeam on light
  • oil light
  • fuel gauge
The run/stop/run will likely be used as the kill switch it's intended to be, but in this case to cut power to the relays on the motor controller.

The horn will apply power to a car horn (from the Ford LTD). I'm pretty sure even a closed-window car or truck will be able to hear it, for those situations when someone is creating an unsafe situation I need to call their attention to (not common, but sometimes I wish I had one for them when they do happen). A bell can't be heard at all by most motor-vehicle traffic, and neither the electric scooter horn (pitiful little buzz) nor the Honda scooter horn (quiet beep) have been heard (or at least, not reacted to) by anyone in such a situation so far. If nothing else I can honk back at all those motor vehicles that honk at me as they pass, which they are not allowed to do (at least in AZ, as far as I am aware). Or as they pass me closer than the required 3 feet, which is EXTREMELY common in the daytime, even when they have multiple other lanes to the left that they could be using, and the lane I am in is even wide enough to accomodate two entire cars! It is far less common at night, as many people seem to assume I'm a motorcycle or something, with the marker lights and signals I have on the Columbia upright, and give me a wider berth than they do a known bicycle.

The brake-light switches (one in each brake handle) will be wired in parallel, and run both to the motor controller's brake-input (to stop the motor during braking) and the brake light. It'll need a transistor or other buffer between the switches and those two functions, since the motor controller runs on 24v or 36v, and the lighting on a separate 12v battery.

The turn signal switch has three wires, one for left, right, and common. The common goes to the turn signal flasher module (electronic, in this case, rather than thermal like the Honda used), which provides power to the signal lights when it is then switched to either left or right instead of off (center). At first, I will just be using the Honda lighting and thermal switcher, because I am still building the LED lighting boards to replace the bulbs with. That system only lights the markers and signals when they are being used to signal. The way I will have my LED system work is the same as on my Columbia upright: the markers will be lit all the time and blink when signalling, by alternating the side and front/rear marker LED sets, using transistors within each of the four light modules.

The front markers and signals will both be amber, simplifying the system, because I can keep using the intact signal lenses, and simply install a row or two of side-facing LEDs on the outer portion of the lenses, with the rest of the LEDs facing forward. The rear markers will be similar, but they will require red LEDs for the side-facing rows, and amber for the rear-facing. This means I must cut a section of the lenses out for the red LEDs to shine thru, and replace it with either red or clear plastic, or more likely simply clear silicone (since that works very well to diffuse the rear amber signals on my Columbia upright bike and trailer light).

The taillight and brake light is very easy: Simply replace the bulb and reflector with a board of LEDs, one-third of which will be wired always-on with the taillight, and the other two-thirds of which will be wired to the brake light. The ratio is to give very high contrast to the braking, so it is very noticeable that I am changing states, just as with cars. On the Honda's incandescent lamp system, it is at least that high a ratio, and might be even greater.

I would like to use clear lenses instead of colored ones for the LEDs, but that will have to wait until I can build my own assemblies to go onto the bike. For now, using the existing Honda parts is the quickest and most reliable way to begin using the bike with a safe lighting and signalling system in place (which was even DOT-approved at the time of it's manufacture), and then replace the incandescents with LEDs as I have them ready, then later transitioning to a custom-made system if I find the need.

I *do* need to transition to LEDs as fast as possible, because the taillight uses almost 1A constantly, the brake light uses another 2.5A, and a pair of turn signals uses 3.8A for about 50% duty cycle pulsing of the lamps, meaning about 1.7A constant for the entire time I am signalling. My headlight (the CCFL scanner attachment) uses about 0.8A constantly. So if I am using 1.8A all the time, plus call it an average of another .2A for braking and signalling during a trip (just a guess), then my 12V7Ah battery isnt' going to last for more than *maybe* an hour before the lights are significantly dimmer than starting brightness, and the turn signals probably wont' work at that point, perhaps earlier (they require sufficient voltage to generate the current thru the thermally-controlled relay in the blinker box). So the taillight/brakelight will be my first LED set to work on, which should reduce the entire current down to about 0.4A during max usage, probably a lot less, depending on how many LEDs in series, plus how many parallel sets I use.

One lesson I learned on the Columbia's lights was that I need to use 3 or less LEDs in series for braking or signalling units. This gives a 6V drop, plus any transistors or diodes I have to use, up to 8V or so I could drop the 12V battery to before I get no lighting out of it. On the Columbia, it's 4-LED strings, so I have about 10V as the lower limit--if I forget to recharge it enough times, or (as happened once) the charger connection or jack fails and I *think* it's charged but it's not (because the charger LED shows full-charge if it's not connected the same as if it's connected to a full battery!), I end up losing all but headlighting completely once it drops below that point. The CCFL runs, dimly, down to about 6 or 7V, and is still bright enough to easily see that I'm there at 8-9V. The taillights on this new bike can still be 4-LED strings, as they have no other drops besides their limiting resistors.

I would *like* to transition to using LED-driver chips that do a buck/boost conversion to run them, so that they will work much more efficiently with less power wastage in the dropping resistors, and will work longer at lower voltage levels with no change in brightness. But that is going to require PCBs and surface-mount chips, which I currently don't have a way to create and solder reliably. I can get the PCBs made but the cost would be about $30 on up, which I don't have to spend right now. The chips I already acquired for developing the safety-bike lighting and control system that I am still stalled on due to total lack of programming skills, and very little electronics-engineering skill (sure, some of what I do might *seem* impressive at first, but it's all hack-and-slash re-purposing, not actual engineering and design). The passive components can come out of all the salvaged junk electronics I have laying around.

On the Honda speedometer/gauge box, I am working out ideas in my head to use the mechanical speedometer, which I'd have to calibrate for the bike. It goes up to 35MPH, which I doubt I would be coming anywhere near, except downhill on the long stretches of 7th Street or Cave Creek Road that run thru the "mountains" here, but I don't even need to pedal to reach those speeds on some parts of that, much less run a motor. :-) Most places are flat, and I expect that with the motor assist, I should be doing 15-20MPH most anywhere that allows those speeds.

It's fuel-gauge I have to work out how exactly it works. It appears to be a position-servo, powered by some separate electronics that match it's position with the float in the gas tank. I won't need that sensor, but I might be able to use the electronics by finding out what input gets me what output (manually moving the float, which I already have entirely out of the tank). Then I just build a battery monitor sensor that measures the voltage across my pack and converts it to whatever that electronics module is expecting, and I can use the fuel-gauge. It appears to take about 80mA to run that box and gauge along with the fueltank float sensor. That's a bit more than one string of LEDs, so no big deal power-wise.

It's a lot easier to read than a bargraph LED display, because it's backlit for darkness, and it's easily read in externally-lit conditions. The LED bargraph displays are nearly impossible to read in sunlight conditions, even in the shadow of a building or tree, unless you stop and cup your hands around it to your eyes, unless you use high-brightness LEDs, and then you'd be blinded at night, unless you add an automatic brightness control to it (which eventually I will have for the bike as a whole anyway, but for now, I don't need the extra complication for just one display).

That said, I may use some type of light sensor to enable/disable the backlight in the module, though more likely I'll just use some fairly dim green LEDs (the original bulb isn't even there, just part of it's socket, and no remains floating around inside).

The "high beam" light I don't have a particular use for, so it will become a functioning indicator light later on.

Turn-signal on light I don't really need, as I can clearly see the signals blinking in front of me, but I will probably still wire it in, since the blinker module will be right there anyway. However, once converted to LED, it won't go in series with the blinker, it will instead have a diode from both L & R sides of the turn signal switch, so that using either of them will engage it, then a dropping resistor and an LED, which doesn't have to be very bright.

The bright/dim headlight switch again won't be used for this, but instead will probably be used to turn the headlight on when on highbeam, but only taillight, running lights and signals when on
low beam. The headlight itself, because it is a wide-angle diffused CCFL, is not very visible in the daytime anyway, so it would be nice to just turn it off to save power (it's the major consumer of my lighting battery) in daylight conditions. I *always* use the lights if I am riding the bike, even in daytime, for the markers and turn signals make me more visible than without them, based on traffic reactions to me with and without them since I built and installed them last year. Thus, no actual "lights off" position, just "no headlight".

Since I have no key for the Honda ignition/lock/etc switch, I'm not using that at all. But I have a weather-resistant Briggs & Stratton electric keyswitch from my junkbox (no idea of it's original source), with two good keys, that will be used to enable main power for both lights and motor. It only has two wires to it, so it will probably be used to engage a relay that switches motor controller power on one set of contacts, and lighting power on the other. I don't really like the keyswitch from the old ScootNGo (currently on the Columbia for motor only, when I had a motor on it), as it has a really cheap key and mechanism, even though it has a separate set of contacts to turn on the lights with, so it'll stay where it is. I have other keyswitches from PC cases and the like, but none of them are weatherproofed in the slightest, so aren't really appropriate for this purpose.

I guess that's enough rambling for this post. ;-)

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