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Thread: Adjustable DC 1800

  1. #11
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    Quote Originally Posted by Frank DuVal View Post
    Circa 1800 would be Leyden Jars.....

    Growing up in Richmond and fascinated with electricity, I knew we had the world's first electric street car system in the world.

    1888 (January 9) – Company opened its first electric line with six cars. This first electric streetcar system served as a demonstration model for municipalities and countries from all over the world.

    Started by the predecessor to Dominion Energy: VEPCO (Virginia Electric and Power Co., Virginia Railway and Power Company, Richmond City Railway Company. Et all.

    Power (electricity) was made by hydro electric, tapping the James River.

    So, I'm with Besoeker, variable energy input (wind, hydro, steam, belt) to a DC generator capable of the loads.
    Steam would probably be your best bet, assuming you could provide a constant pressure reservoir. After that, hydro.

  2. #12
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    The problem persisted until the end of that century. In the late 1890s Lyne Bradley solved it with his invention of the “variable resistance carbon pile”, a number of carbon discs in a stack to which you applied variable pressure with a screw clamp mechanism, which varies the resistance through the stack. In 1903 he got funding of $1,000 from his family Doctor, Stanton Allen and formed the “Compression Rheostat Company”, which 7 years later was changed to the “Allen - Bradley Company” that still exists today. Their later development of the “Type J Potentiometer” became the worlds lagerst selling electrical component until the invention of the transistor. A-B sold off their potentiometer business in the 80s to Clarostat, who still makes and sells the Type J pot.
    __________________________________________________ ____________________________
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  3. #13
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    Quote Originally Posted by Jraef View Post
    The problem persisted until the end of that century. In the late 1890s Lyne Bradley solved it with his invention of the “variable resistance carbon pile”, a number of carbon discs in a stack to which you applied variable pressure with a screw clamp mechanism, which varies the resistance through the stack. In 1903 he got funding of $1,000 from his family Doctor, Stanton Allen and formed the “Compression Rheostat Company”, which 7 years later was changed to the “Allen - Bradley Company” that still exists today. Their later development of the “Type J Potentiometer” became the worlds lagerst selling electrical component until the invention of the transistor. A-B sold off their potentiometer business in the 80s to Clarostat, who still makes and sells the Type J pot.
    And for many years, even into the 1960's or later some automobile voltage regulators used a combination of a spring and a solenoid to vary the pressure on a carbon pile to vary the field current in an automotive generator to regulate its output voltage for the car or truck electrical system. Properly adjusting it was in some ways magic! You varied the position of the base of the pile and varied the tension in the spring to achieve regulation.

  4. #14
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    A 1953 Chevrolet truck I once owned used a switch-mode voltage regulator, of sorts.
    Battery voltage was fed to a relay coil. If it was low, the relay arm didn't move off the bottom contact and full voltage was applied to the field winding.
    If it was low, the relay arm pulled in to the top contact and the field was shorted.
    If it was between limits, the relay arm didn't make contact with either contact and field current was applied through a fixed resistor.

    "Proper adjustment"? There was a procedure in the book, but you were lucky if it landed somewhere between boiling the battery dry and allowing it to freeze. Batteries weren't expected to last more than one year and needed refilling almost as often as the fuel tank.

    - - -

    But to answer the original question: Maybe an array of batteries in series with multiple selectable taps?

  5. #15
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    Quote Originally Posted by Jraef View Post
    The problem persisted until the end of that century. In the late 1890s Lyne Bradley solved it with his invention of the “variable resistance carbon pile”, a number of carbon discs in a stack to which you applied variable pressure with a screw clamp mechanism, which varies the resistance through the stack.
    Slight digression - mods, lend a sympathetic ear.
    I knew them well. Early in my career I was known as the carbon pile man. They were used in differential gearbox regulators, typically on paper machine drives. These were typically 10 to 15 individual DC drives that had to have precise speed holding. Wet paper isn't very strong. One shaft of the gearbox had the reference speed motor, the other was the actual running speed of that drive section. The difference was the output shaft that compressed the carbon pile until the two inputs matched precisely. Speed control was absolute.

    There is a more prosaic side to this tail. I was young and single. I got sent out on jobs that none of the other engineers would touch with a barge pole.
    Si hoc legere scis nimium eruditionis habes.

  6. #16
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    Quote Originally Posted by gar View Post
    181010-2438 EDT

    If you needed a continuously variable DC voltage supply to run experiments in the early 1800s what would you use to perform this function?
    How about a carbon pile?
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  7. #17
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    181012-2016 EDT

    Larry Fine:

    In 1800 little was known about resistance, resistors, conductance, current, or what was, or how did electricity function. Thus, not much was known on how to generate or adjust voltage, or what voltage was.

    Volta snd Galvani 1800 https://en.wikipedia.org/wiki/Alessandro_Volta about 1/3 down.

    Orsted 1820 https://en.wikipedia.org/wiki/Hans_C...an_%C3%98rsted Electromagnetism about 1/4 down.

    Ohm 1827 https://en.wikipedia.org/wiki/Georg_Ohm about 1/2 down. This is the date I am interested in. How did Ohm generate his variable voltage?

    Today not much is taught about electrical history. It is interesting to put your self back in time, and conjecture what you might do or experiment with given the knowledge of that time.

    Many of the responses to my original post projected today's knowledge to a time when such devices were unknown or did not exist.

    .

  8. #18
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    Ohm could have used a set of discrete voltages by adding cells to a battery stack rather than using a continuously variable voltage, and may not have made the distinction clear as he described his experimental results.

    Sent from my XT1585 using Tapatalk

  9. #19
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    181012-2056 EDT

    GoldDigger:

    By at least 1940 Ford, probably not as early as 1936, was manufacturing a voltage regulator assembly that consisted of three relays. A voltage regulating relay, a current limiting relay, and a cutout relay.

    The early story on the voltage regulator is at https://ethw.org/First-Hand:The_Stor...tage_Regulator

    The GE and Ford voltage regulators used an oscillating relay to modulate the average current to the generator field coil. The oscillation frequency would be a function of the mechanical time constants of the voltage relay and the electrical time constants of the generator. Because arcing occurred at the contacts regulator life was a function of contact material and metal transfer. 1000 hours was somewhat of a design goal. Many tests were run on various contact materials to try to improve life. One semester in the early 1940s I worked in my classmate's father's, Emil Zoerlein, electrical engineering lab installing and removing regulators on test stands for life testing. Zoerlein headed up all Ford product engineering testing including the test track, and dynamometer engine testing. He designed the high speed test track at Ford Airport, and developed an environmental hot, cold, and wind tunnel test chamber for a full size car. Later I worked in the radio section of electrical engineering.

    This oscillating relay regulator was quite good at voltage regulation, and included temperature compensation.

    What manufacturer used the carbon pile regulating means?

    .

  10. #20
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    181012-2137 EDT

    GoldDigger:

    Ohm used a stack of thermocouples, and varied the temperature.

    .

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