Speedlimiter circuit using lm2917

Discussion in 'The Projects Forum' started by Manthi, Nov 13, 2010.

  1. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    Hi.

    I am building on my scooter yamaha aerox speedlimiter.
    Rpm-limiter won´t work in this case becos going up the hill would bee a problem and the ruptrure.(?)

    I tought use reed-switch and lm2917 and the output i put a reley, potenteometer and condensator.
    I don´t have enought experience. so where i wuold start :)

    -How i get reed-switch swing bouth sides of 0V
    -wheel sise is 15.22 so onthe 55km/h (34.4MPH)
    so the frequency is about 9.17
    -multiplying would make it accurate?
    -and whic condensator and resitor rates i start?


    And makin it controlled c1 and c2 i put potenteometer before condensator.

    Any ideas?



    (new in forums and bad english) :D
     
  2. tom66

    Senior Member

    May 9, 2009
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    How do you plan to limit the speed of the vehicle itself?

    The LM2917 converts RPM to voltage. You will need to calibrate the RPM to convert it into MPH. Then, you could use an LM339 to compare the speed. You might want to add some hysteresis to prevent it switching on and off rapidly at the target speed.
     
  3. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    My scooter is using cdi ignition so when target speed is overed the relay start cutting(some frequency) the impulse coil. And the ignition get some delay and motor won´t get full power.

    So lm2917 work like that you put some relay which is 5v and you have set on condensator and resitor the value rpm and when value is overet you get on output 5v?
     
  4. tom66

    Senior Member

    May 9, 2009
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    No, that won't work. The LM2917 won't be able to drive a relay, and the relay may switch on at any point below 5V (it could switch on at 3V, for example.) You need an LM339 or similar comparator IC and a transistor to drive the relay. How are you powering this circuit? Straight off the 12V battery?
     
  5. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    Ok. I take the power scooters battery( 12v) 5v was a example to relay

    So can you draw me the circuit and lets thinks the resistor and condensator values lately?

    and will the potenteometer and condensator work if i wan´t it controlled (it easier find the right value)
     
  6. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    http://www.national.com/ds/LM/LM2907.pdf
    Page 8 have ready circuit.
    So will i need still the comparator drive to relay

    R1- Potenteometer 10kOhm
    C1 500µf
    C2 5nf

    And how i get the reed switch to jumpping both side 0V (+-)

    Can i use same reed-switch whit my sigma speed meter?
     
  7. tom66

    Senior Member

    May 9, 2009
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    Sorry, I'm a bit busy at the moment. I've been doing some things.

    First thing you will need to solve is the 12V supply. You can't use that as it will have high voltage spikes on it due to the engine and lighting. If there's an ECU module or similar, see if you can get a stabilised voltage out of it, like 5V or something.

    If not, I can draw up a surge protected regulator circuit.

    The speedometer circuit can connect to a LM339 comparator. You could use a potentiometer to adjust the trip speed.
     
  8. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    I will open the sigma and look at the circuit.
    And its a digital and using 7segment display type.
    And-gate(if nothing another way can found) this wuold work and i still need power to control to relay.
    There is a voltege-regulator on my scooter but i dont know how stabil is it.
     
  9. tom66

    Senior Member

    May 9, 2009
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    The regulator is probably only for the lights and not suitable for this project.

    I don't understand how an AND gate would work.

    The power from the relay can be taken from the 12V battery. It's not crucial that the relay have surge protection as they are usually resilient devices.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    What are you planning to use to create the LM2917 input? A reed switch driven by a magnet on the wheel?

    That won't work very well, as the input frequency will be very low.

    Does the scooter have a chain drive, or shaft drive?

    If it's a chain drive, you might use a Hall-effect sensor to detect the passing of teeth on the chain sprocket. You would need to construct a suitable bracket to hold the Hall-effect sensor and wiring in the correct position for reliable operation.

    How many teeth does the sprocket have, and what is the outside diameter of the rear wheel?

    We don't know where in the world you are. It will help us to help you if we know your approximate location; such as country and state or province. You can add the information to your profile by clicking on the "User CP" link on the menu bar, typing the information in the "Location" box (about 2/3 of the way down the page), and then clicking the "Save" button at the bottom.
     
  11. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    Yea, my scooter is using variator.
    I am from finland and law say our scooters max speed can be only 45km/h
    And how they are throttled that way you cannot get up any hill....
    So the eletronic limiter is way beter.

    The frequency will be about 10hz

    I will post a picture on my speedometer circuit and u guys can tell me where i stuck the comparator :)
     
  12. tom66

    Senior Member

    May 9, 2009
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    I am curious, why not just limit yourself to 45 km/h? Watch the speedo and make sure you don't go over...
     
  13. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    But but... The nice police man will test scooters(and its a legal to test) i and if they get over 65 u lose your license and you get lots of money lose.

    I don´t have today time to work on whit sigma.
     
  14. SgtWookie

    Expert

    Jul 17, 2007
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    Let's go back to the 1st post for a bit.

    According to this page:
    http://bikez.com/motorcycles/yamaha_aerox_r_2008.php
    Front tyre dimensions: 130/60-13
    Rear tyre dimensions: 140/60-13

    Are you planning on taking the speed from the front or the rear tire/tyre?

    According to this page:
    http://www.avonmoto.com/products/high-perf-scooter/viper-stryke
    ... their 130/60-13 tire does 681 revolutions per km; at 45km/hr, that would be a frequency of 8.5125 Hz.
    Their 140/60-13 tire does 665 revolutions per km; at 45km/hr, that would be a frequency of 8.3125 Hz.

    Well, in this case, an LM2917 probably would not be your best bet, as 8.3Hz-8.5Hz is a very low frequency. It might be easier (and cheaper) to make a "too-frequent pulse detector" circuit using a couple of 555 timers, or one 556 timer. This is basically the reverse function of a "missing pulse detector" circuit.

    This is easier than you might think; just use a capacitor between the switch and the input, and a 10k or so resistor to ground on both sides of the capacitor.
    I'm not certain how you obtained the dimension(s) of your wheel/tire.
    I don't know if the site(s) that I found accurately represent your scooter and your particular tire sizes.

    Not necessarily.
    As I already mentioned, at such a low input frequency, the LM2917 may prove a bit too troublesome for your purposes.

    On the other hand, a too-frequent pulse detector should be fairly easy to build out of common components.
     
  15. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    55(-60)km/h is much beter, becos all roads speed limit is a 60-80 so Imagine you driving 45km/h and all car´s are passing by...
    So i just let my speedometer be alone but can i still use same reed-switch??

    We are using meteric-system

    Can i draw me and i start building it then :)
    My school have circuit maker(?)
     
  16. SgtWookie

    Expert

    Jul 17, 2007
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    OK, so which tire/tyre are you going to use to get the speed measurement?

    Are the numbers I came up with accurate/correct for your scooter?
     
  17. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    The front feel is 13" but the rubber comes there to
    So when wheel spins ones the scooter goes 1.53..m forward
    build it that way (if posible) that it can be controled 7-11hz And relay and i put rest ones on that?
     
  18. tom66

    Senior Member

    May 9, 2009
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    Really, I didn't know that. Are you sure they'd accept a home-made solution or would they require a properly certified solution?
     
  19. Manthi

    Thread Starter New Member

    Nov 13, 2010
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    They are only interest what is max speed. Inspection(?) is more interested about limiters.(yea i don´t have to never ever go to there)
     
  20. SgtWookie

    Expert

    Jul 17, 2007
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    See the attached schematic.

    SW1 is actually your reed switch; it's normally open and closes for a brief moment when a magnet on a wheel passes by. I used a relay and signal source so that I could simulate it.

    R2 is where you set the speed limit. Once you find the correct setting, you should really remove the pot, measure it, and replace it with a fixed resistor, as pots are not as reliable as fixed resistors.

    U1 has a time-out of about 95mS when R2 is adjusted properly. If triggers from the reed switch occur too often, U1 does not time out, and it's output never goes low. This causes U2 to time out a short time later, and its' output goes low, energizing the relay.

    As shown, the output to "points" would be connected to the high (coil) side of the points, but that might result in the coil getting overheated. I don't know what arrangement you have for your ignition, but a relay could be wired up in whatever arrangement that's appropriate for your ignition - perhaps to disconnect power from it.

    [eta]
    If your scooter is fuel injected, it would be preferable to interrupt the injector circuit. Otherwise, when the ignition system is disabled, you will be dumping a raw air/fuel mixture into the exhaust system that is extremely flammable, and will likely ignite with a loud "BANG!" when the ignition is again enabled.
     
    Last edited: Nov 16, 2010
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