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Designed to break?

Discussion in 'Electronic Design' started by Charles, May 29, 2007.

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  1. Charles

    Charles Guest

  2. John Larkin

    John Larkin Guest

    Never. In electronics design, it would actually be difficult;
    electronics doesn't have predictable wearout mechanisms like
    mechanical parts do.

    We design our stuff to be as reliable and as rugged as we reasonably
    We sometimes calculate product MTBF using the Bellcore standards. Our
    actual field-failure rate on most products is a lot better than the
    calculations predict.

    As far as consumer products go, if you buy the cheapest stuff, expect
    it to break sooner. A $29 microwave oven can't be expected to be very
    good. My GE microwave lasted 15 years; my VW threw a gear after 14. My
    Tek scopes, Sony camera, Vaio laptop, home furnace, garage door
    opener, are all 5-15 years old and working fine. I'm looking at an art
    deco electric clock on my desk, made in the 1930's, that still keeps
    perfect time.

    Tektronix did one sampling plugin that used mercury batteries to
    back-bias the schottky sampling diodes. They were special welded-tab
    button cells, very hard to get at, and soldered into the circuit. They
    are very difficult to replace, and last a few years.

  3. Joerg

    Joerg Guest

    Same here. Absolutamente not.
    My old Minolta had a mercury cell. The trick I used was to get a low
    cost modern watch battery and to get down from its 1.55V to the 1.35V of
    a mercury cell I hung a OA91 Ge diode in series. The voltage was dead
    on. Works like a champ again, just in time for when our foxes had their

    "Designed to break" brings up some grief we (and probably lots other
    folks in the US) experience a lot: Malibu Light timers. The last plastic
    gear before the big timing wheel is usually shot after 3 years. I've
    asked them twice how to get spares because it's easy to replace. No
    answer. Silence. So every time this 5c part breaks we have to either buy
    a new timer-transformer for $40 or so or wait until a whole set with
    transformer and ten lights comes up in a sale for around $30. Quite
    wasteful, considering that only the timer-transformer needs to be replaced.
  4. D from BC

    D from BC Guest

    It's designed to break when companies hire designers from
    alt.binaries.electronics.basic. :p
    D from BC
  5. I don't think things are designed to break. Not even MS Windows. Its
    built broken and becomes obsolete when support is discontinued. But I

    Economics dictates a point of diminishing return for an investment in
    additional MTBF. In addition, economics limits the market value of
    designing in maintainability. An example will illustrate my point: Some
    time ago, I did research prior to selecting a flat panel TV set. One
    attribute mentioned in reviews was the expected life of the display.
    Plasma sets were the worst, tending to darken with age. LCD displays
    were better, but their life was determined by the life of the backlight
    source. Huh? In most cases, this is a couple of fluorescent lamps. It
    should be a no brainer for the average consumer to snap in some new
    lamps if the set were designed to make the job simple. But they (the
    manufacturers) figure that after 5 years, the average consumer will be
    willing to pitch the set out anyway. There are too few of us who would
    change our purchase decision based upon this detail, so it isn't worth
    the additional cost.

    I don't think its as much about the possibility of future sales based on
    a shorter product life. After all, the consumer who is in the market for
    a replacement unit probably perceives the quality of their original
    selection to be low, having just experienced a failed unit. This
    customer is more likely to select another brand, so that's a lost sale
    one way or the other.
  6. Joerg

    Joerg Guest

    There is one: Me :)

    Not necessarily. It depends on whether the failure was premature and how
    the manufacturer dealt with it. If it was premature and they let me
    hang, refusing to furnish spare parts and so on, yes, they'll earn a
    pretty much eternal entry on our "Do not purchase anymore" list.
  7. Take the new one and make a mold from it (silastic RTV?). Cast new gears as
    needed from two part epoxy. You could even try a Metal Molder!



  8. Joerg

    Joerg Guest

    Yeah, I just wanted to avoid that mess ;-)

    I mean, what's wrong with offering a simple spare part to their
    customers? Other companies like Bissell (vacuums) do their best to make
    customers happy by sending spares. Often they don't even charge
    anything. Is there a better supplier than Intermatic for these timers?
  9. I have a digital one - starts at sunset and runs for 1, 2, 3 ... hours.
  10. mpm

    mpm Guest

    On May 29, 5:39?pm, John Larkin

    Well, I guess that rules all of us out as being missile defense
    (Technically, I guess you could say those are designed to break!)

  11. mpm

    mpm Guest

  12. Joerg

    Joerg Guest

    We were cured of those. Bought one, ran for 2 hours minus 50% plus a few
    hundred percent. Exchanged it, same thing. Later I peeked into one that
    someone else was throwing away for the same reason. A concoction of
    chips and electrolytics, like many of those ill-fated 555 circuits. Oh
    man. I guess some "engineer" hadn't figured out yet how to do a long
    range timer around a CD4060. What are they teaching them these days?
  13. I've never intentionally done that, but many things created from technology
    will eventually become obsolete. Sometime, parts are no longer made. A
    product I designed, the Ortmaster, uses a parallel port in a special way
    and must have MSDOS to run the software. New computers don't come with
    MSDOS, and even if you could install it, parallel ports are often no longer

    In a way, this is fortunate for me, because I am setting up an upgrade
    option where I will replace the internal PC Board and supply new Windows
    software that can run the system through a serial port or USB. This is a
    device that sells for $3000, and the retrofit will sell for about $1000,
    for a parts cost of about $100.

    This new product contains a PIC, and it would be possible to program
    planned obsolescence into the product. It could have a RTC, so after a
    certain period of time, it could shut down operation. I was considering
    something similar, but not so drastic. The device should be calibrated on a
    yearly basis, and the calibration data is contained in the program memory
    (which is supposed to be better than EEPROM). The calibration date could be
    included, and the software could check this date against its own RTC and
    pop up a warning that calibration is due.

    Actually I think this is a good idea, because it is very important that
    calibration accuracy be assured, and many of these units that I get in for
    repair are long overdue. Sometimes when I repair them, the calibration can
    still be checked, and usually is pretty close, but sometimes it is off by a
    significant amount. I charge a flat rate of $100 for NIST calibration, and
    an extra $100 for repair, plus shipping, so it's reasonable. However, most
    of the shops that have them don't want to part with them for even a few
    days, so they nurse them along until they stop working.


  14. I used a digital Intermatic timer to turn a window air conditioner on
    and off for years I haven't needed it much, since I got sick. The AC
    is on almost year round since I've become disabled. the motorized one
    on the water heater has been in use for eight years and still works
    fine. The older ones had the motors fail at about five years, but
    spares were sold at Home Depot.

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida

  15. Microdyne built command destruct receivers to destroy off course

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
  16. Well, me too. But manufacturers don't cater to us. If you want a
    microwave oven, you get to select between the models that are aimed at
    the mass market.
    They (consumer electronics manufacturers) want to sell you another unit.
    If they sell you a repair part, they've lost ther sale of a new unit. If
    they don't sell you a repsir part and you go away thinking dark thoughts
    about them, that's the same sale they've lost.
  17. It was built broken. After a time, they just stop supporting it.

    All software is built broken. Bits don't wear out. The bugs just become
    exposed over time as probability dictates that eventually, the
    combination of conditions necessary to unearth them will occur.
  18. Reminds me of:

    If Operating Systems Drove Your Car to the Store

    You get in the car and try to remember where you put your keys.

    You get in the car and drive to the store very slowly, because attached to
    the back of the car is a freight train.

    Windows NT
    You get in the car and write a letter that says, "go to the store." Then you
    get out of the car and mail the letter to your dashboard.

    Macintosh System 7
    You get in the car to go to the store, and the car drives you to church.

    You get in the car and type grep store. You are given a list of 400 7-11's
    in your area and 50 grocery stores. After picking one and reaching speeds of
    200 miles per hour en route, you arrive at the barber shop.

    After fueling up with 6000 gallons of gas, you get in the car and drive to
    the store with a motorcycle escort and a marching band in procession.
    Halfway there, the car blows up, killing everybody in town.

    During the whole trip to the store, your gas meter reads full and the car
    runs fine. On the way home, under the strain of the extra cargo, the car
    inexplicably runs out of gas, even though the meter still reads full.

    You walk to the store with Ricardo Montalban, who tells you how wonderful it
    will be when he can fly you to the store in his Lear jet.

    S/36 SSP (mainframe)
    You get in the car and drive to the store. Halfway there you run out of gas.
    While walking the rest of the way, you are run over by kids on mopeds.

    An attendant locks you into the car and then drives you to the store, where
    you get to watch everybody else buy filet mignons.

    You use up tremendous amounts of gas to go very slowly and only get to see
    an image of the store.
  19. amdx

    amdx Guest

    I'm still using a Frigidaire microwave oven we purchased in 1983!
    I did replace the lightbulb once or twice over the years. Uses a good
    old mechanical timer and a pot to set the duty cycle.
  20. Not break, but I certainly can predict when some things will wear out,
    within a reasonable tolerance.

    Best regards,
    Spehro Pefhany
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