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Modify Velleman Kit - Transistor Assisited Ignition, kit no. K2543

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by sign216, Jan 12, 2017.

  1. sign216

    sign216 Member

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    How can you get rid of the voltage regulator? Even a 12v system needs one, doesn't it?
    Or does your new schematic include an electronic regulator?

    As for the emergency starting, I'm still dealing with the orig. 6v generator coil. It's the only part of the wiring system that cannot easily be replaced (aside from the whole wiring harness). So I'm fearful that in an emergency the generator coil wouldn't provide sufficient spark for a 12v ignition coil. Particularly since the generator coil is marginal for the 6v coil (i.e. the bike must be push-started instead of just kick started).
     
  2. spec

    spec Well-Known Member Most Helpful Member

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    It uses a voltage limiter. The specific voltage from the dynamo does not matter.
    What is the generator coil? It is not shown on the schematics, or have I missed it.

    As far as I can tell the generator has three connections: chassis (earth), field, and rotor (output). I there something else. Are you referring to the resistor in the generator field circuit?
    This would need to be tested, but it is quite likely that the FT3R coil would give a better spark for emergency starting.:)

    spec
     
  3. sign216

    sign216 Member

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    I'm a rube, and a little unclear as to the difference between a voltage limiter and a regulator. Am I right that the limiter is a "cheap and easy" version of the regulator?


    By "generator coil" I meant the generator itself, since the generator is comprised of coils of wire + magnets. I'm worried that this particular 6v generator won't have sufficient output to fire a 12v ignition coil, especially since this 6v generator isn't designed to provide a starting current, like a starting magneto is.

    What are you referring to by "FT3R coil?" Is that part of your proposed system?
     
  4. dave

    Dave New Member

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  5. spec

    spec Well-Known Member Most Helpful Member

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    The voltage limiter looks exactly the same as a voltage regulator. But it just prevents the generator voltage from rising above a predefined voltage to protect the generator and the rest of the bike electrical system.

    The critical difference is that all of the energy produced by the generator, even at low RPM, can be used by the next circuit, which charges the battery at exactly 14.1V, an ideal voltage for charging a 12V lead acid battery. This would be a better accuracy than achieved by the existing mechanical regulator, which is still liable to be good as it is made by Bosch.

    As far as I can tell the generator is perfectly standard with a field and rotor connections.

    Like I said, it is quite likely that the emergency starting will be improved with the FTR3R coil

    'FT3R coil' is shorthand for 'Flame Thrower coil, (3 OHM primary), 12V, 40KV output voltage.

    Yes, the FTR3 coil is part of the outline system and would probably be appropriate for ant 12V system, but that is still to be discussed.

    spec
     
    Last edited: Jan 23, 2017
  6. sign216

    sign216 Member

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    I'll keep the system at 6v.

    Last night I researched the topic of converting cycles from 6v to 12v while keeping the 6v generator. An issue is that at low engine speeds the 6v generator won't put out enough to run the 12v system. It'll sap the battery, until you start riding faster.

    Reportedly the generator an be re-wound for 12v, but that'll be a project for another day. I'll keep th system at 6v.
     
  7. spec

    spec Well-Known Member Most Helpful Member

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    The low voltage when the generator is spinning slowly can be taken care of by the SMPS. It is a better approach than rewinding the generator.

    But as you say, a 12V system is probably a bridge too far.

    spec
     
  8. sign216

    sign216 Member

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    I'll order the 6v 1.5 ohm Flame-Thrower coil.
    When I return from my trip, I'll measure the bike and get the largest 6v battery that'll fit.
    Then I can test the coil to see how hot it gets.
     
  9. sign216

    sign216 Member

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    Wards/Benelli Motorcycle group on Yahoo yielded an alternative; a complete replacement of the charging and ignition system by Powerdynamo of Germany. It's 12v, battery-less, with electronic ignition.
    It is 400 Euro.
    Sounds great, but I didn't want to replace the whole system, and didn't want to pay nearly that much.
    Let me calculate what the Velleman kit will be, incl. the new coil, battery, etc.

    Attached is the wire diagram and a link to the system.
    http://www.powerdynamo.biz/eng/systems/7127/7127main.htm
     

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  10. shortbus=

    shortbus= Well-Known Member

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    The question was asked to find out if the bike has a separate 'generator'. Many of those era bikes used an extra coil on the magneto as a generator. I got that maybe this is how this bike is from sign saying that the generator had magnets in it. The bikes that I'm used to working with that have magnets to generate the electricity are alternators not generators. Now he's talking about field coils in the generator. Hard to keep up with this thread.
     
  11. sign216

    sign216 Member

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    SB,
    It does not have a separate coil for ignition.
    It has a DC generator which charges the battery, and the battery supplies power for the standard coil + battery ignition system.

    The complete 12v system from Powerdynamo (above post 108) sounds great, but I'm not looking to change everything, or spend that kind of $. I simply want to improve on the existing 6v points system. Hence the Velleman transistor assisted igntion, and the high performance coil. I'm hoping to use those to improve the current ignition, without the $$$ and "black box" solution of Powerdynamo.

    I'd prefer to do it myself. But...I recognize you are the experts, so I call on your advice.
     
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  12. sign216

    sign216 Member

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    Ballast Resistor - I learned of two options in cars that could work here to keep the coil from overheating.

    1. Switched resistor - The ballast resistor is switched out during starting, so that the coil gets full voltage. After start up the resistor is switched in, so the coil doesn't heat up. In cars the switch is tied to the starter solenoid, but I could it manually.

    2. Temperature sensistive resistor - I quote from an article: "The ballast resistor ... is a temperature sensitive, variable resistance unit. A ballast resistor is designed to heat up at low engine speed as more current attempts to flow through the coil. As it Heats up, its resistance value increases, causing lower voltage to pass into the coil. As engine speed increases, the duration of current flow lessens. This causes a lowering of temperature. As the temperature drops, the resistor allows the voltage to the coil to increase." From http://newautoaa.blogspot.com/p/primary-circuit-of-ignition-system.html

    These options look like they would do the trick. Do either seem viable?
     
  13. sign216

    sign216 Member

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    I am happy to report that I've bought a replacement ignition coil and battery.

    Coil: MSD 8222 high vibration coil
    Inductance 8 mH
    Maximum voltage 45,000 Volts
    Peak current 140 mA
    Primary resistance .7 OHMs
    Secondary resistance 4.5K OHMs
    Spark duration 350 uS
    Turns ratio 100:1

    Battery:
    11 amp hr 6 volt, standard lead-acid


    I've added acid to the battery, and it's charging now. I think the next step is to test the coil + ballast resistor on the battery current, to see if it overheats.
    What ohm ballast resistor should I get?
     
  14. spec

    spec Well-Known Member Most Helpful Member

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    Hi Sign,

    How are you going to drive the coil- directly from the points?

    I would start with 3.3 Ohms, 10W to give a current of 1.5A and a coil dissipation of 1.6W

    Then 2.2 Ohms, 10W to give 2A, and a coil dissipation of 2.8W

    Then 1.8 Ohms, 10W to give 2.5A and a coil dissipation of 4.4W

    Then a finally, 1.2 Ohms 25W to give 3A and a coil dissipation of 6.3W

    But please remember that I am not advising that you do this as the coil is at risk.

    Good luck all the same.:)

    spec
     
    Last edited: Feb 3, 2017
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  15. sign216

    sign216 Member

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    I was going to use the Velleman kit modified to take greater than it's usual 4 amp limit.
    Because the high performance coil uses over 4 amps, I wanted to make use of it's potential.
    Recall that just the standard points has a 4 amp limit too, but a modified transistor kit might be capable of more, and would enable the high performance ignition coil too.

    Although your questions raises a new possibility. If the starting circuit shunts off the ballast resistor so it's not in the circuit, then that's plenty of extra performance by itself. After starting I could switch the resistor back in, to protect the coil. This might be possible with the standard points set up, so I don't have to use the transistor assisted ignition.

    I am thinking correctly?

    I.e. the high performance coil, with only 0.7 ohms, would give better starting. With a ballast resistor, when running, the coil might not overheat and still give above average results.
     
  16. spec

    spec Well-Known Member Most Helpful Member

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    What I am suggesting is to take a gently gently approach and gradually increase the current.

    At this stage we do not know what current the coil needs to be fully charged with energy.

    I would also suggest using the points with a 220nF, 500V, min capacitor across the points and take the Vellerman ignition out of the frame at this stage.

    But don't let me influence you- these are just my thoughts.:)

    spec
     
  17. sign216

    sign216 Member

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    Recall that the issue probably isn't insufficient current, but overheating the coil. The coil manufacturer said that the coil wasn't suitable for single cylinder engines because of the long dwell.

    I'm hoping that a ballast resistor would protect the coil, and allow its use.
     
  18. spec

    spec Well-Known Member Most Helpful Member

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    OK :)

    spec
     
  19. alec_t

    alec_t Well-Known Member Most Helpful Member

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    I'm trying to figure how that enters the equation. Primary current or secondary? If primary, then is it the maximum allowable prolonged current without coil damage? If secondary, it seems to conflict with the output voltage and secondary DC resistance.
     
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  20. sign216

    sign216 Member

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    I think: peak current 140mA

    Is part of the inductance calculation. I've never had more than a passing study of inductance, but the web yields this formula:

    [​IMG]

    W is energy in Joules
    L is inductance in Heneries
    I is current in amps, squared

    I got the formula from this site; http://www.rfcafe.com/references/electrical/inductance.htm
     
  21. sign216

    sign216 Member

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    I am a neophyte, so any specifics on the test?

    I.e. is this correct; I attach battery leads to the + and - terminals on the coil, with the resistor in series, and measure how hot the coil gets.

    Over what time period?
     

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