Some electric locomotives also used liquid rheostats, in particular in Italy for early three-phase AC types such as the FS Class E550. Some direct current designs also used them as starting resistors. Liquid rheostats were sometimes used in large (thousands of kilowatts/horsepower) wound rotor motor drives, to control the rotor circuit resistance and so the speed of the motor. Electrode position could be adjusted with a small electrically operated winch or a pneumatic cylinder.
|
|
Carbon fiber is also used as the heating element in many high-end heated car seats. Blankets can be purchased with rheostats that regulate the heat by managing body heat and blanket temperatures, ensuring a comfortable experience.
|
|
Position # 9: Serial connection of electric engines, Rheostats are excluded. Position # 10: Transitional step of excitement weakening (67%) Position # 11: Excitement brought down to (50%) Position # 12: Electric traction engines are connected in parallel, rheostats are added, and the excitement is 50%. Position # 13 .. 15 Rheostatic starting, engines connected in parallel, 100% excitement Position # 16 Engines are connected in series of two, and excitement is 100% Position # 17 Transitional step of excitement (67%) Position # 18 50% excitement, engines connected in parallel. Engineer's controllers are mounted in control panels.
|
|
Azimuth Co-ordinator used by Pink Floyd, made by Bernard Speight, 1969 (Victoria & Albert Museum, London) The Azimuth Co-ordinator was the first panning control for a quadraphonic sound system, at that time a new concept. Pink Floyd became the first band to use it in their early shows. The Azimuth Co-ordinator uses four rotary rheostats housed in a large box. The rheostats were converted from their standard 270 degrees rotation to operate over the narrower 90 degree range imposed by the physical constraints of the control lever with the box top aperture.
|
|
L pads may not necessarily use continuously variable rheostats, but instead a multi-position rotating selector switch wired to resistors on the back. Tapped transformers are not L pads; they are autoformers. L pads can also be used at line level, mostly in pro applications.
|
|
The locomotives had 3-axle monomotor bogies with each set of 3 axles coupled by gears. Speed regulation was by rheostats and series-parallel control. The motors had double armatures so there were four "demi-motors" which allowed three motor groupings: full series, series-parallel and full parallel. The power controller had 28 steps.
|
|
But in 1910 Chagovets arrived and immediately applied for funding for improvement of physiology equipment. He got 20,000 golden roubles (appr. $10,000 of that time which with inflation correction means almost $250,000 in modern US dollars) and bought the most novel German equipment: galvanometers, kymograph, rheostats, microscopes, timers etc. He organized modern animal operation clinics taken as the specimen Pavlov's lab.
|
|
Four Sided Triangle was an early effort by Hammer Films. The laboratory set includes "a welter of retorts, alembics, rheostats and plain, old neon tubing". This chaotic, improvised laboratory setting has been contrasted with the sophisticated labs portrayed by Universal Horror pictures of the 1930s. The picture relies on a minimum of trick photography and special effects, which may have been compromised by its limited budget.
|
|
Traction control was provided by three different motor combinations (series, series- parallel, parallel) through banks of resistor-based rheostats. The transmission was rather noisy, but at the time, the crew's comfort was not a high priority. The carbody was in a single steel piece, mounted on an articulated chassis. The large bonnets at the ends limited the visibility of the rails, and they were reduced in size from the third series.
|
|
In 1962 the owner/manager was John Coyle with the program director being Dillard Carerra. The station had an unusually high power of 119,000 watts in full stereo. (The power has since been reduced to 99,000 watts, because the antenna height was increased.) The engineering of the audio was routed through a huge audio mixer with slider controls utilizing German silver rheostats. Audio phasing was a problem at that time.
|
|
A speaker L pad is a special configuration of rheostats used to control volume while maintaining a constant load impedance on the output of the audio amplifier. It consists of a parallel and a series rheostat connected in an "L" configuration. As one increases in resistance, the other decreases, thus maintaining a constant impedance, at least in one direction. To maintain constant impedance in both directions, a "T" pad must be used.
|
|
Before the adoption of series-parallel control, rheostats were widely used to control the speed of cars. In November 1888 Electric Car's general manager, George H. Condict, secured a US patent (No. 393,323) for a switch that improved on Hunter's series-parallel design. His most important advance (though neither he nor Hunter, who acted as his patent attorney, realized it at the time) was to integrate the series-parallel and rheostatic methods in a single control mechanism.
|
|
Dimmers based on rheostats were inefficient since they would dissipate a significant portion of the power rating of the load as heat. They were large and required plenty of cooling air. Because their dimming effect depended a great deal on the total load applied to each rheostat, the load needed to be matched fairly carefully to the power rating of the rheostat. Finally, as they relied on mechanical control they were slow and it was difficult to change many channels at a time.
|
|
To stabilize the load, the mixture must not be allowed to boil. Modern designs use stainless steel electrodes, and sodium carbonate, or other salts, and do not use the container as one electrode. In some designs the electrodes are fixed and the liquid is raised and lowered by an external cylinder or pump. Motor start systems used for frequent and rapid starts and re-starts, thus a high heat load to the rheostats, may include water circulation to external heat exchangers.
|
|
During his research, he recognized that the device could also be employed to vary the intensity of light. A lighting dimmer existed at the time, but was expensive, complicated, and necessitated the use of large rheostats, about 10 in (25 cm) in size. Though there were dimming devices already in use for theater lighting, they were far too big and bulky for use in homes. Spira successfully manipulated a thyristor, a solid-state semiconductor small enough to fit into the wall box that housed a standard light switch.
|
|
The L pad attenuates the signal by having two separate rheostats connected in an "L" configuration (hence the name). One rheostat is connected in series with the loudspeaker and, as the resistance of this rheostat increases, less power is coupled into the loudspeaker and the loudness of sound produced by the loudspeaker decreases. The second rheostat is connected between the input and ground (earth). As the first rheostat increases in resistance, the second rheostat decreases in resistance, keeping the load impedance (presented at the input of the L pad) constant.
|
|
Muntzing is the practice and technique of reducing the components inside an electronic appliance to the minimum required for it to function. The term is named after the man who invented it, Earl "Madman" Muntz, a car and electronics salesman who was also a self-taught electrical engineer. In the 1940s and 1950s, television receivers were very complex pieces of equipment, often containing upwards of 30 vacuum tubes, as well as transformers, rheostats, and other heavy electronics. The consequent high price limited their potential for high-volume sales.
|
|
Liquid rheostats used as motor start switches, circa 1900 A liquid rheostat or water rheostat or salt water rheostat is a type of variable resistor. This may be used as a dummy load or as a starting resistor for large slip ring motors. In the simplest form it consists of a tank containing brine or other electrolyte solution, in which electrodes are submerged to create an electrical load. The electrodes may be raised or lowered into the liquid to respectively decrease or increase the electrical resistance of the load.
|
|
Muntz started plans to sell television receivers in 1946, and sales began in 1947. Muntz played the madman in his unorthodox television commercials, but in fact he was a shrewd businessman and a self-taught electrical engineer. By trial and error, taking apart and studying Philco, RCA, and DuMont televisions, he figured out how to reduce the devices' electrical components to their minimum functional number. This practice became known as "Muntzing". In the 1940s and 1950s, most brands of television receivers were complicated pieces of equipment, commonly containing about 30 vacuum tubes, as well as rheostats, transformers, and other heavy components.
|
|
Door controls were provided in the cabs, and a facility to isolate either of the two units from the leading cab was also included. For the first time on tube stock, all control circuits were switched by cam- operated micro-switches. They were used on the traction and brake controller, the disconnecting units, the fault isolating switches, the door controls and other control equipment, and resulted in a significant reduction in the routine electrical inspection needing to be carried out. Rheostatic braking was used on the trains, and required amendments to the standard P.C.M. (Pneumatic Camshaft Motor) controllers, to include the switching in of the rheostats.
|
|
Normally it took the operator about ten seconds to slowly advance the rheostat across the contacts to gradually increase input power up to operating speed. There were two different classes of these rheostats, one used for starting only, and one for starting and speed regulation. The starting rheostat was less expensive, but had smaller resistance elements that would burn out if required to run a motor at a constant reduced speed. This starter includes a no-voltage magnetic holding feature, which causes the rheostat to spring to the off position if power is lost, so that the motor does not later attempt to restart in the full-voltage position.
|
|
Universal motors are compact, have high starting torque and can be varied in speed over a wide range with relatively simple controls such as rheostats and PWM choppers. Compared with induction motors, universal motors do have some drawbacks inherent to their brushes and commutators: relatively high levels of electrical and acoustic noise, low reliability and more frequent required maintenance. Universal motors are widely used in small home appliances and hand power tools. Until the 1970s they dominated electric traction (electric, including diesel-electric railway and road vehicles); many traction power networks still use special low frequencies such as 16.7 and 25 Hz to overcome the aforementioned problems with losses and reactance.
|
|
A small dynamo driven by belt from the flywheel provided charge for the accumulators which enabled electric starting of the engine, lighting for the carriage, and the 'exciting current' for the field coils in the main dynamo, controlled by rheostats at either end of the railcar. The engine speed could likewise be controlled via a throttle from either end of the railcar. The output from the main dynamo was sent to two electric motors, both mounted on the bogie underneath the engine room. In 1923, No. 3170 was re-engined with a more powerful 225HP engine, allowing it to haul an unpowered coach, an early version of the multiple units used today.
|
|
Pole changing and cascade (concatenation) working was used to allow two or four different speeds, and resistances (often liquid rheostats) were required for starting. In Italy freight locomotives used plain cascade with two speeds, ; while express locomotives used cascade combined with pole-changing, giving four speeds, 37, 50, 75 and 100 km/h (23, 31, 46 and 62 mph). With the use of 3,000 or 3,600 volts at 16⅔ (16.7) Hz, the supply could be fed directly to the motor without an onboard transformer. Generally, the motor(s) fed a single axle, with other wheels linked by connecting rods, as the induction motor is sensitive to speed variations and with non-linked motors on several axles the motors on worn wheels would do little or even no work as they would rotate faster.
|
|