e-cigarette inside Scalextric car, high(ish) current switching from tilt switch?

Discussion in 'The Projects Forum' started by garethj, Mar 28, 2015.

  1. garethj

    Thread Starter New Member

    Mar 28, 2015
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    Hi from a newbie, I've got a reasonable understanding of simple DC electrics but I'm stuck with this bit of electronics.

    I want to run an electronic cigarette inside a Scalextric car so that when it goes around corners it switches on and smoke comes out from the back tyres. Not exactly the solution to world peace, but it keeps me and the kids amused.

    The Scalextric car gets anywhere between 0V and 15V from the rails, the voltage varies depending on whether you've got the throttle fully open, fully closed or somewhere in between. The hand controller has a simple variable resistor inside it. The motor takes (at an educated guess) 1.5A maximum.

    The electronic cigarette has a coil of resistance wire which is about 1 ohm and what I thought was that with a tilt switch inside the car I can use it to switch the cigarette's coil on. A quick look around shows me that a tilt switch can switch about 20mA but I believe the usual power is 3.7V and 800mA.

    First, what do I need (a modern version of a relay) to switch the coil from a tilt switch? Second, is there a better way to do this instead of having a heavy battery inside the car? Maybe use a smaller battery and take power from the rails to top it up?

    I don't think I can directly switch the coil from the rails because I know if you put two cars on one track they slow down a lot, so if I power the coil on it will probably slow down the motor. The Scalextric's power supply isn't very high current.

    Thanks for any help on this, I know it's a little odd.
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    368
    Run it from the motor supply via a voltage regulator (Google LM317) as the extra weight of a battery in the car would have a more detrimental effect than the extra current draw, which is probably quite small.

    I'm not sure how you would switch it on, though. A tilt switch would, in practice, give very erratic operation. Perhaps some kind of voltage detector circuit so that it's triggered at a particular "throttle" position; this could be as simple as a miniature 12V relay.

    I wonder if this counts as an automotive modification?
     
    Last edited: Mar 28, 2015
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Can you supply any more specs on e-cig battery, best I can find is 3.7 V LiI, 2000 mA hr & coil .1 ohm to 3 ohms.
    Tilt SW come in several forms, one built like a pendlum looks promising- just from memory
     
  4. garethj

    Thread Starter New Member

    Mar 28, 2015
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    Thanks, blocco. I might run it with a battery to start with and then try with a voltage regulator once I've got a better idea of current draw. You're right about the tilt switch, perhaps something like a reed switch (or hall sensor might be more resilient?) close to the rear axle - when the back of the car slides it's no longer seeing the rails down the middle of the car so that could trigger the smoke. Is it possible to find a regulator or transistor with a timer built in, so I can run the smoke for 1 second after actuation?

    Bernard, I believe the coil is 1 ohm but that can be changed as I can wind fewer or more turns around the wick. Some use around 2 ohms but the lower resistance gives more smoke which is probably what I'll need. As for the battery, bigger will last longer and I've seen 500-1500mA hr. As a non-smoker I've got no idea how long it will last, and it would be a very heavy smoker that would mimic the smoke coming out from a car around a twisty circuit. I'm not afraid of some trial and error.

    Thanks for your help so far!
     
  5. garethj

    Thread Starter New Member

    Mar 28, 2015
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    0
    I'm just looking at packaging one of these 18350 cells inside the car - they're quite big! Am I wrong to look at mobile phone batteries which are flat?
     
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