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  1. hevans1944

    Volts to ohms for fuel sender

    @Gryd3: I think the Arduino is "overkill" for an embedded microprocessor project as simple as this one, but it is (1) what the OP has; (2) is fairly easy to get up and running; (3) is "supported" by zillions of sketches available for free download to help point the way; and (4) has plenty of...
  2. hevans1944

    eMOSFET and common emitter amplifier

    My point exactly! Except I would call them tools instead of the more pejorative term crutches. Gee, Colin, did you really download that PDF and squint at the schematic and comments?! I am impressed. Pretty good explanation, too, and not one mention of beta or alpha or anything else irrelevant...
  3. hevans1944

    help with a basic 5 LED circuit

    Yep, sure it will. Two relaxation oscillators running independently should do the trick. Stick in whatever color LEDs you want: red, yellow, green, blue, even white. Elegant solution, Colin.
  4. hevans1944

    help with a basic 5 LED circuit

    Nice circuit, Colin, for powering up white or blue LEDs, but the problem we are considering is how to make the red and yellow LEDs flicker like a lit candle.
  5. hevans1944

    Volts to ohms for fuel sender

    The Arduino is a good platform for testing "proof of concept," but after you get it programmed and working you may want to port it to a PIC for compactness of size. This could be a profitable after-market item you could sell to the Harley-Davidson community. Won't get rich doing that (most...
  6. hevans1944

    help with a basic 5 LED circuit

    @duke37 The 555 was my first thought too, but it doesn't provide the pseudo-randomness of a flickering rocket exhaust so I discarded the idea. A long ring counter (maybe sixty-four bits long) made with discrete integraded circuits, with taps located at "random" locations, the taps driving the...
  7. hevans1944

    eMOSFET and common emitter amplifier

    Well, maybe hate is too strong a word. My first encounter with simulation was in a college class in the 1970s where we were required to solve differential equations representing circuits using the Runge-Kutta method of approximation... which algorithms we had to program on Hollerith punched...
  8. hevans1944

    Has anyone used an aurora (Honeywell) motion sensor (PIR) with arduino?

    Haven't used one, but check out the installation notes here. Looks like two wires are for 12 V DC power and two wires are for the alarm. Some models have two more wires for an anti-tamper circuit.
  9. hevans1944

    Volts to ohms for fuel sender

    @Calabashmc The smallest value you can get for the digital potentiometer in your link is 10,000 ohms, which is incompatible with a 90 ohm sender the panel display wants to see. But your thinking is in the right direction: a voltage-controlled variable resistance. There is a fairly simple...
  10. hevans1944

    Measuring the speed of a Frisbee & Boomerang

    Think of the video images of astronaut trainees in the centrifuge, how the acceleration distorts their faces. Just substitute an accelerometer for the faces. Of course that doesn't provide rotation speed directly, but it does allow you to calculate it (probably). Anyone up for calculating the...
  11. hevans1944

    what am I

    The Kelvin-Varley's main claim to fame as a precision voltage divider is unequaled., I think its best feature is constant input resistance, because each decade is switched in such that it always presents the same impedance to the previous decade. Very handy when used with precision voltage...
  12. hevans1944

    HELP! Wireless Keyfinder Project

    Have you looked here?
  13. hevans1944

    eMOSFET and common emitter amplifier

    Okay, i hate to say this... but this is one instance where an analog simulation program, such as LTSpice (free), will shed some light on the subject. And you can use it to draw and upload decent schematics too.
  14. hevans1944

    Circuit Help Request

    That looks like it will work.
  15. hevans1944

    help with a basic 5 LED circuit

    Well, you have the resistors in all the right places. I agree with @Gryd3 that two AA cells probably won't hack it for long. Three (4.5 V) or four (6 V) would be my minimum, sizing the resistors accordingly. I would scale those up to at least "D" size if you expect the display to run very long...
  16. hevans1944

    Measuring the speed of a Frisbee & Boomerang

    No, @LazyBoy, use my method! It's a lot more complicated and requires sophisticated electronics and software processing. Where's the fun in doing it @BobK's eminently practical way?!
  17. hevans1944

    Flyback joule

    I do "social networking" here and in other forums. Facebook... not so much. Post your questions here so the entire community can see and help you. I suspect you are trying to build a classic "joule thief" circuit and you should Google that phrase for background information. A fly-back...
  18. hevans1944

    what am I

    Only if dinos shed their teeth in old age.:p
  19. hevans1944

    ECG Circuit Problem

    Ah! And yet another "instructable" bites the unwary novice. Looks to me like you are seeing the power-line radiating into your rig from wiring in the walls and whatever mains wiring that happens to be nearby. My heartbeat is regulated by an implanted device to be about 72 beats per minute, so...
  20. hevans1944

    Flyback joule

    I don't see a light bulb on your schematic. Where are you connecting the bulb? If you are trying to operate the light bulb from the secondary winding, you will need a neon lamp and a large-values current-limiting resistor in series with the lamp... perhaps ten to a hundred meg-ohms or greater...
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