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school project idea needs help — Parallax Forums

school project idea needs help

science_geekscience_geek Posts: 247
edited 2009-01-09 05:49 in Propeller 1
ok, i have to give a demonstration speech at school, and i thought an ion lifter would be really cool, my first question is, is an ion lifter a good topic, or is there another one you guys you can think of that would incorporate the prop with, my second question is, if i were to pulse a transistor on and off with the prop at a very high speed and then hook a transformer up to it, and then a second tranformer hooked up to that and so on till i got·a high enough volts

Comments

  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-01-08 02:17
    I'll just beat everyone to the punch - Be careful with the high voltage, man! It's really nasty stuff even when you're being careful. I was messing around with my railgun capacitor bank(forgetting it was charged), touched both leads, woke up on the ground with half my face not working... 2kv is dangerous, and what you're talking about with the lifters, is in excess of 30kv.

    Regardless, cool project!
  • P!-RoP!-Ro Posts: 1,189
    edited 2009-01-08 05:05
    Depends on the amperage, philldapill [noparse]:)[/noparse]

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    PG
  • RubrChickenRubrChicken Posts: 39
    edited 2009-01-08 16:40
    You could make a coilgun! The prop would allow you to have a whole bunch of coils and allow you to trigger them in sequence. And use relays! Transistors are good, but if they break, there goes your prop. Make sure they are fast triggering relays, though.
  • J. A. StreichJ. A. Streich Posts: 158
    edited 2009-01-08 17:11
    Building up large voltage is only dangerous if amperage is high also. The a Tesla coil, for example, can output high voltage arcs that are very high voltage and low amperage. Cool looking lighting that you can touch, and power light bulbs with. Now, touching the coil itself, however, can be very dangerous. That said, the high EMF can cause problem with other electronics in the area including pace makers.

    Just pulsing a pin to build a large charge seems like a waste of a prop.... unless it's doing other things as well.

    Class project ideas using the prop that come to mind:
    1. Servo bot similar to BOE (but able to process multiple "stimuli" at once)
    2. Coil gun (though still no need for so much smarts)
    3. Audio Oscilloscope
    4. Game and/or Game System (think Hydra)
  • StefanL38StefanL38 Posts: 2,292
    edited 2009-01-08 19:41
    Hello,

    great effects with the sugestions above.
    If somebody get hurt by that you are in really big trouble

    I have a complete different idea
    I call it "walking a function"

    This means there is a carpet 1x5 meters long. It has marks at every meter. At the 0m-end there is a monitor placed on a pillar showing a text start at X meters. Then a countdown of 10 seconds.
    and then you see a X-Y-diagram and a function is drawed with f.e. color yellow into the X-Y-diagram
    and a white cursor starts moving forward the person should walk forward and backward
    to adjust the Y-value in that way that the white cursor fits the yellow line.
    The software measures the distance of the person from the monitor with an ultrasonic sensor
    and draws a white line according to the distance

    By this way the person "walks" the function. A new experience what it means if the Y-value of a function y := f(x) goes up and down with X-value
    or the y-value stays the same for 1 < X < 3 or what ever

    I saw this in a mathematical museum.

    The TV or VGA-Output of the propeller should be good enough to show this on a screen

    So this would even be didactic and I think your teacher would like it

    best regards

    Stefan
  • science_geekscience_geek Posts: 247
    edited 2009-01-08 23:27
    actually, i just talked to my teacher today and she said a coil gun would be fine,(we are going to call it an electromagnetic pulse steel sphere emitter)
    i plan on showing how to build one out of several cameras, quick question though, is there any solution to getting it to fire from the prop, like an scr(it think thats what there called) and im going to at the end pull out a turret and mount the barrel to it
  • kwinnkwinn Posts: 8,697
    edited 2009-01-09 00:48
    No problem having the prop fire it. And yes, an SCR can be used to fire it. So can a bipolar or FET transistor. Just make sure they are able to handle the current and voltage, and that the prop pin(s) are isolated from the high voltages.
  • jmgjmg Posts: 15,172
    edited 2009-01-09 00:52
    Power MOSFETS would be the best to drive the coils, as you need to remove the drive
    as soon as the ball has advanced.
    Use as high a voltage as you feel safe with
    (maybe 30V) on the coils, and to allow a fast decay, a zener clamp rather than a
    clamp diode. Plenty of energy storage cap will be needed, as this will draw amps.
    Sensing the location of the ball will be interesting [noparse]:)[/noparse]
    I see Slot Opto interrupter devices come up to 8mm wide ?

    Fire at a target or perhaps make a nut-cracker ?
  • jmgjmg Posts: 15,172
    edited 2009-01-09 01:09
    Digikey search finds OR524-ND as an 8mm slotted opto sensor, Logic output.

    Add a large power resistor to fire supply, before the storage caps, to give some
    safety should things stay on longer than you intend ! [noparse]:)[/noparse]
  • science_geekscience_geek Posts: 247
    edited 2009-01-09 02:58
    actually i was going to use a bunch of cameras(i already have a 9 cap bank built) thats why is asked about an scr, and if i end up frying something on the scr and i use an optoisolator, is there any chance at all even a small one that i could fry the prop,

    actually i really like the nut cracker idea, maybe i will work on seeing if that will work
  • jmgjmg Posts: 15,172
    edited 2009-01-09 03:07
    SCRs are not ideal to drive inductors, as they cannot be turned off easily.

    Power MOSFETS are easier to get, and work better.
    You could fry-protect the prop, with a series gate resistor, and a clamp Zener.
    Usually tho, a low milli-ohm mosfet will just sag the supply.
    I would start with a current limited supply (not a car battery....)

    Cameras could be tricky to interface to, and have a shutter and scan delay, plus
    will find it hard to see the ball inside the coils.. ?

    Put a LED on the coils, so everyone can see them fire. LEDs are visible, even with
    very short current pulses.
    A display of ball speed on exit could be good too ...
  • grasshoppergrasshopper Posts: 438
    edited 2009-01-09 03:14
    Why not keep it safer and cooler by levitating a magnetic sphere using a electromagnet, the propeller, and a light sensor. Programing the propeller using a PID would be a great challenge and the cool factor is there.
  • TJHJTJHJ Posts: 243
    edited 2009-01-09 04:01
    If yolur looking for help on the actuall design,



    Nuts and Volts Vol 29 No 3

    March 2008



    http://www.nutsvolts.com/index.php?/magazine/issue/2008/03



    Just might help you not wake up on the floor drooling... But my CDI igniton has done it to me a few times now... Good Luck



    TJ
  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-01-09 05:49
    I can vouche for that. [noparse]:)[/noparse]
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