Welcome to the NavList Message Boards.


A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

Add Images & Files
    FW: Lights etc.
    From: Doug Royer
    Date: 2003 Oct 10, 14:41 -0700

    Jared,this is good stuff.I'm going to FW it to the group.I do hope that is
    ok with you.Thanks for the info.I'll write Mon. about what I find out
    reguarding these.
    -----Original Message-----
    From: Jared Sherman [mailto:jared.sherman@verizon.net]
    Sent: Friday, October 10, 2003 14:32
    To: Royer, Doug
    Subject: Re: Lights etc.
    That's the theory, somewhere between 32 and 60 cycles and the eye thinks
    they are always on. There's more of a debate about subjective/objective
    brightness, but also apparently a real time factor that an LED takes a mucj
    longer fraction of a second to come to full brightness. That is, it is "on"
    right away, but it doesn't reach full brightness for something like 1/10th
    second--way longer than the blink.
    I don't know, I've just heard "he said she said" on this.
    The main spike that gets thrwon in a boat is from the starter motor. When
    you stop cranking the starter, it continues to spin for a short time and in
    that time it is acting as a generator, so it can add +14V to the 14V on the
    power lines, spiking 28VDC for less than a second--but that's eternity for
    some solid state devices. Those caps &tc you have are good protection. I'd
    batted this around with some ham operators and electronics techs and there
    was some debate, especially since a boat may be running 10VDC (low battery
    limping home and hoping the lights are still on) to 12.8V (full battery) and
    13.8-14.4 when the alt/generator is running. In order to get optimum light
    from the LED's they want a specific voltage, not a range. So...
    The jury was out on whether to use a single-chip DC regulator at the LED's
    (more expensive, best controller), or just spike protection (zener diode or
    other simple device) with resistors to limit current. I was cleaning up the
    instrumentation power lead on a boat last year and wound up building a small
    box with a circuit board in it. One external fuse for the instrument power,
    two sets of overvolt protection (fast spike protection + zener diodes since
    no one would swear which one was best, and the spike protectors DO wear out
    over the years) and then a tiny buzzer that should only sound if there is an
    overvoltage, allowing us to shut the instruments manually if the electronics
    all go out or the alternator goes berserk.
    Unfortunately I could only find an aluminum mounting box, and LORD! does
    that shop-grade aluminum get pitted fast in a salty atmosphere.

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site