Electricity: measurement instruments


 

 

 

 

 

   

ASTATIC MIRROR GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:   Unsigned   Price: Purchase date:

  Description
  The instrument stands on a circular wooden basis with three leveling screws. From this basis rise a curved pole whose the top end is on the vertical of the centre of the basis. A thread hanging from the pole holds an astatic system formed by two magnetic needles joined in parallel. The poles of these needles are opposed so that they are not influenced by the terrestrial magnetic field. A mirror is placed at half height of the thread.
  The current that must be measured passes between the two magnets and makes them turn in the same direction. Through the rotation, amplified by the mirror, we can obtain the current intensity.

Menu

 

 

   

NOBILIíS GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:   Unsigned   Price: Purchase date:

  Description
  It is based on an astatic system formed by two parallel magnetic needles that are joined one of the other with opposite polarities. They hang from a thread. In this way the influence of the terrestrial magnetic field is eliminated.
  One of the needles is free to rotate inside a coil, while the other is outside and is used as an index of the rotation.
  For small angles, the current intensity is proportional to the rotation of the needle.

Menu

 

 

   

DíARSONVALíS GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:
Siemens & Halske
Price: L 281.25 Purchase date: 1908

  Description
  This is díArsonvalís galvanometer of the Siemens firm.

Menu

 

 

   

DESPRETZ-D'ARSONVAL GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:
Officine Galileo - Firenze
Price: Purchase date:

  Description
  The instrument rests on a base of black glass or ebonite, with a back foot and two leveling screws.
  The magnet is vertical with polar expansions and a central nucleus of ductile iron.
  The upper suspension is a bronze ribbon and the bottom one is helical with an elastic thread. The tension of the ribbon is adjustable from above. With a 400 ohm coil the sensibility is 40 mm per microampere with the scale at one meter. The instrument is protected with a prismatic glass case fixed on the base, but the forward glass is mobile.

Menu

 

 

   

THOMSONíS GALVANOMETER


  Function
  Measure of the intensity of current.
Maker: Unsigned Price: L 150 Purchase date: 1882

  Description
  The galvanometer is composed by a multiplier made of a long and thin wire. Inside the multiplier a lightly small conical mirror is hanging, with a silk thread. Behind the mirror there is a very light magnet. A magnet placed above the multiplier helps to regulate the zero of the instrument.
  A lamp with a very brilliant flame is placed behind a screen. Through a slit it send a light beam onto the mirror that reflects it on graduated scale placed at a distance of 60 cm from the galvanometer and enhances the very small deviations.

Menu

 

 

   

THOMSONíS ASTATIC GALVANOMETER WITH SCALE


  Function
  Measure of the intensity of current.
Maker: Unsigned Price: L 450 Purchase date: 1887

  Description
  Thompsonís astatic system is made of two series of thin parallel magnets with opposed polarities, pasted on a circular mica plate and connected to a pole. The needles can oscillate inside a couple of coils. The current passes across the two coils in opposite directions. A mirror placed between the two needles is useful to measure the rotation angle.
  Besides this there is a curved magnet placed outside the instrument. It is used to regulate the zero and the sensibility of the instrument.

Menu

 

 

   

MOVING COIL GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:
Max Edelmann - Munich
Price: L 317 Purchase date: 1908

Menu

 

 

   

DEMONSTRATION GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:Phywe Price: Purchase date:

  Description
  The instrument is mounted on a rectangular table. In the centre there is the multiplier inside which we have the magnet that can rotate on a horizontal axis.
  A long needle is joined to it. The other end of the needle is used as the index of a scale held horizontally by tow brass columns.

Menu

 

 

   

STRING GALVANOMETER


  Function
  Measure of the intensity of current.
Maker:
Max Edelmann - Munich
Price: Purchase date:

  Description
  The instrument is made of a conductor wire placed between the polar expansions of two U shaped magnets. When the current passes the wire moves.
  A detector of the shift is placed between the two magnets.
  From one side we have a source that send a light beam which arrives on the wire detected by a microscope placed on the other side.

Menu

 

 

   

TANGENT GALVANOMETER


 Function
  For measuring the intensity of current.
Maker: Unsigned Price: L 300 Purchase date:
Cat. 1882

  Description
  A declination magnetic needle is placed in the centre of a circular circuit (turn) of 33 cm diameter, placed along a magnetic meridian.
  If the current passes through the circuit, the needle is subject to a couple of forces that tend to dispose it perpendicularly to the turn. The couple intensity depends on the current intensity that passes in the turn.
  With a simple calculation we can see that, in a given place, the current intensity is proportional to the tangent to the deviation angle.
  When the angle is 45į the created field of the current is equal to the terrestrial field.

Menu

 

 

   

UNIVERSAL GALVANOMETER FOR DEMONSTRATION PURPOSES


  Function
  For measuring the intensity of current and the difference of potential.
Maker:
Officine Galileo - Firenze
Price: L 220 Purchase date: 1918

  Description
  It is a moving coil instrument of great sensibility, assembled vertically on a mahogany table. On the basis there are the binding posts, the additional resistance, the parallel resistance and the plug inverter of these resistances.
 We can use it as a sensitive galvanometer of 200-0-200 mV; or as direct reading ammeter of 10-0-10 A and as a direct reading voltmeter of 50-0-50 V.

Menu

 

 

   

MOVING COIL AMMETER AND VOLTMETER


  Function
  For measuring the intensity of current and the difference of potential.
Maker:
Tecnomasio - Milano
Price: Purchase date:

Menu

 

 

   

MOVING COIL AMMETER AND VOLTMETER WITH BASIS


  Function
  For measuring the intensity of current and the difference of potential.
Maker:
Max Kohl - Chemnitz
  Price:
L 56.10 + 15.30
L 56.10 + 15.30
Purchase date: 1908

Menu

 

 

   

TELESCOPE WITH READING SCALE


  Function
  It is used with instruments that have a mirror joined to a mobile coil.
Maker: Dall'Eco - Firenze Price: L 200 Purchase date: Cat. 1882

  Description
  It is made of a telescope and a ruler placed horizontally above them.
  By pointing the telescope on the mirror we focus the scale of the ruler. The rays reflected by the mirror strike the ruler. If the mirror rotates, on the ruler we have an amplified shift of the point where the reflected rays fall. For small angles the shift is proportional to the rotation angle.

Menu

  home