Tuesday, September 05, 2006

Cruise control project complete...

Just got back from the final final shakedown cruise. The first time, it wouldn't maintain a speed higher than 71mph. So I got back home, and realized: hey, a motorcycle revs higher than a car. So I looked at the DIP switch settings, and they were set at 4000ppm (pulses per minute) like the manual had told me to set them for a manual transmission car. Well, at 4000rpm, my motorcycle is barely going 60mph. So I set it at the next higher, 5000ppm, and not only will the cruise now set all the way up to 85mph (woo!), but it got rid of the last of the jerkiness when engaging the cruise (setting the switches to 'high powered vehicle' made the jerkiness acceptable, but now it's about as smooth as you'll get with a high-revin' motorcycle engine).

For the brake light -- I'm leaving the stock bulb in there now,. The problem is that the low resistance to ground thingy is a critical safety feature. If I put a relay in there and the relay failed in a closed position, I'd have hard ground to the cruise control brake sensor all the time and it would never disengage. Right now, if the wire breaks to the cruise control sensor, it loses its hard ground through the brake light bulb (which is about 3 ohms) and disengages. This avoids the situation of hitting the brakes to disengage the cruise and it won't disengage!

So I need that 3 ohm resister called a "light bulb" in the circuit, or it won't work (at least, not safely). The LED module has about a 1K ohm resistance with the low voltage that the cruise puts out, which is too much. I could of course add a 3 ohm power resister, but if I'm going to convert power to heat, I might as well make light with it too! Which brings up the *real* solution: add an additional (non-LED) brake light to the rear of my bike. That way I can put the flashing LED module back in, because I'll have a new 3 ohm resister (the additional brake light) to ground the cruise control!

Now for my next project...

-Badtux the Mechanic Penguin

5 comments:

  1. Can you use both lights?

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  2. Of course. All I have to do is fabricate a vampire tap under the rear fender where the blue wire from the brake switches comes in via a push-together connector, waterproof the shit out of it (this is under the rear fender after all!) and bring the new wire out to wherever I mount the new brake light. Then when I put the brakes on, both lights will come on -- the flashing VERY bright LED one, and the one above it. That should leave little doubt that I'm stopping!

    The next question is where I should mount the new light. I think I'll mount it on my topbox, which lives on my bike pretty much 100% of the time (only time I take it off is when I'm working on my bike, because I can't get my seat off with it on because the seat has to slide back to get its tongue out from under the frame and with that big box behind the seat, it can't slide back). That'll also put it up high where it can shine right into the eyes of the cell-phone-talkin' makeup-smearin' moron who's about to rear-end me...

    - Badtux the Lighting Penguin

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  3. So when God said "Let there be light", you where the electrian?

    ReplyDelete
  4. I'm glad you got it working OK. Check this out.

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  5. Yeah, I've seen that before. But I need an incandescent brake light in the circuit. I bought one at Kragen's last time I was there, I just need time to install it, my boss just assigned me a major new project...

    -BT

    ReplyDelete

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