December 10, 1919 was the day an application was made by Mary Hallock Greenewalt to patent the rheostat. US1357773A - Rheostat
- Google Patents
It is interesting to note Mary's invention used current varying through a potentiometer to alter intensity of light - used as her invention of a type of visual music she called "Nourathar" Mary Hallock-Greenewalt - Wikipedia
Had she taken the next vital step of varying intensity of light to vary resistance,
she might have also invented the LDR.
- Google Patents
It is interesting to note Mary's invention used current varying through a potentiometer to alter intensity of light - used as her invention of a type of visual music she called "Nourathar" Mary Hallock-Greenewalt - Wikipedia
Had she taken the next vital step of varying intensity of light to vary resistance,
she might have also invented the LDR.
"A" rheostat (actually several related types); not the general principle, which seems to be unpatented.
Read the "I claim" on page 6. It claims a very specific implementation to give nonlinear response. The mechanical details are clever, but not a universal rheostat.
Prior patents using rheostats without claiming invention:
Google Patents
Google Ngram Viewer
Read the "I claim" on page 6. It claims a very specific implementation to give nonlinear response. The mechanical details are clever, but not a universal rheostat.
Prior patents using rheostats without claiming invention:
Google Patents
Google Ngram Viewer
I think Bell’s original telephone was a moving needle in an acid bath type rheostat actuated by a diaphragm with sound waves.
I think we may find that Mary, via a recently published book
9780809511914 - Mary Hallock-greenewalt: the Complete Patents by Mary Hallock-greenewalt - AbeBooks
had subsequent patent inventions that were necessary for her
later invention the Sarabet, and is the invention you are referring to
as far as I can see presently confusing using the wording in your post " specific implementation" as the original rheostat patent. US1357773A - Rheostat
- Google Patents
This brief article refers to the Sarabet invented 28th April 1925 , and the 1932
patent infringement by General Electric, so some 6 years after the rheostat patent.
Women of Invention: Life-Changing Ideas by Remarkable Women - Charlotte Montague - Google Books
I have ordered the book and will be happy to clarify, the later separate invention of,
as it appears as presently , each form of rheostat.
US122267A - Improvement in rheostats or resistance-coils - Google Patents. December 26, 1871.
Claims only the specific wiper/slider design; apparently the rheostat was an established thing.
The word "rheostat" seems to have been coined about 1845 by Wheatstone. Museo Galileo has a rheostat apparently by Wheatstone, notable for not having a lengthwise sliding contact. (Wire wound from a wood spool to a brass spool.) This is murky because the "Wheatstone Bridge" is really Wheatstone's description of the Christie bridge. Wheatstone may have developed improved variable rheostats for use with a bridge.
Claims only the specific wiper/slider design; apparently the rheostat was an established thing.
The word "rheostat" seems to have been coined about 1845 by Wheatstone. Museo Galileo has a rheostat apparently by Wheatstone, notable for not having a lengthwise sliding contact. (Wire wound from a wood spool to a brass spool.) This is murky because the "Wheatstone Bridge" is really Wheatstone's description of the Christie bridge. Wheatstone may have developed improved variable rheostats for use with a bridge.
A rheostat and a potentiometer are two different things, although often they may be realised with one component wired in different ways. A rheostat inserts a variable resistance in a circuit to control current. A potentiometer is a variable potential divider to control voltage.
The majority of potentiometers are variable resistors so it infers any voltage then is subjected to that resistance, and Ohms law tells us V/R = I So to assess potentiometers as
a divider to control voltage alone, or some how magically devoid of current, is inaccurate.
No. A variable resistor has two terminals. A potentiometer has three terminals. You can wire a potentiometer as a variable resistor (also known as a rheostat) by ignoring one of the end terminals.
I never said that a potentiometer is "devoid of current", magically or otherwise. A potentiometer (component) used as a potentiometer (circuit device) is there to control voltage by acting as a potential divider. A potentiometer (component) wired as a variable resistor is there to control current by adding resistance to a circuit loop.
I never said that a potentiometer is "devoid of current", magically or otherwise. A potentiometer (component) used as a potentiometer (circuit device) is there to control voltage by acting as a potential divider. A potentiometer (component) wired as a variable resistor is there to control current by adding resistance to a circuit loop.
The original potentiometer was used to measure potential (hence the name) and carries no current from the wiper. You null out the wiper current and use the linear relationship between length of wire and resistance. Basically its a length of resistance wire along a graduated scale. Typically used as two arms of a Wheatstone bridge. Still done as physics demonstrations today, for instance https://www.nvistech.com/images/pdf/Nvis6032.pdf
Potentiometer as an electronics component seldom has accuracy requirements (some 10-turn
pots being the exception).
Potentiometer as an electronics component seldom has accuracy requirements (some 10-turn
pots being the exception).
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