1300 mm Helmholtz Coils - Versin en Espaol (clic aqu)

Ferronato - BH1300-3-A

---  A three-axis Helmholtz coil-set, for laboratory and general purposes.

---  Suited for many magnetic measurements and experiments, in DC and AC.

  • Same field/current ratio for the three coil pairs, with a round value easy to handle: 200 T/A (or 400 T/A, or 2 x 100 T/A, in according to wiring, easy to modify); in direct or alternate current.

  • Two-wire (bifilar) winding, what allows several configurations in connections.

  • Accurately made, with error smaller than 1% in the generated field.

  • Thanks to its simple supporting system and joining by screws, the coil arrangement can be modified with relative easily.

  • Coils on aluminium alloy forms.

  • Each aluminium form provides an usable extra turn, with wiring to the terminal block. An example of application is the generation of a small magnetic field to modulate the main one. The forms can be also configured to generate small gradients.  - Click here for more details -

  • The aluminium forms also act like partial shields for electric fields.

  • The coils can undergo heatings to at least 100 C without damage.

  • Robust construction but with a reasonable weight.

  • Totally constructed with non-ferromagnetic materials.

  • Excellent quality/price ratio.

  • There are versions of one and two axes available, with similar characteristics:

    • BH1300-1A-A, one axis, horizontal. Only the X pair.

    • BH1300-1B-A, one axis, vertical. Only the Z pair.

    • BH1300-2A-A, two axis, horizontal/horizontal.  X and Y pairs.

    • BH1300-2B-A, two axis, horizontal/vertical. X and Z pairs.

    There is a page available in "PDF" format with images of these versions: -Click here to download this -



Field/Current ratio 200 T/A (2.0 Gauss/A). For each pair, X, Y or Z. Maximum error: 1%.

(Optionally 400 T/A, or 2 x 100 T/A, by modifying the wiring at the terminal block.)

Maximum field 800 T (8.0 Gauss) in a steady way / 2.0 mT (20 Gauss) during 2 minutes. Each axis.
Maximum current 4.0 A in steady mode / 10 A during 2 minutes (start temp: 20 C). Each axis.
Isolation voltage 250 V DC minimum, between winding and form and between windings. Tested to 500 V DC.
Magnetic field homogeneity

Differences smaller than 1% respecting to the centre, in a spherical volume of 404 mm in diameter, centred in the coils.

Differences smaller than  5%  in a spherical volume of 586 mm in diameter.

The volumes to 1% and 5% are larger along some directions.

Orthogonality error 0.2, maximum.
Connection Two terminal blocks, one for the coils and another for the forms, with M4 screws ( 4 mm).
Maximum working temperature 80 C for the set / 100 C for the coils, as measured on its surface.
Coil cross-section Winding: 27 x 13 mm, maximum. Total (form): 30 x 15 mm
Materials Enamelled copper wire winding filled with epoxy resin. Coils forms of aluminium alloy, with interior epoxy coating, with terminal boards in resin/glass fibre (FR4) with covers in PVC. Supporting pillars in polypropylene tube. Upper and lower boards in foamed PVC. Brackets in Acetyl ("Delrin"). Screws in brass and Nylon.
Maximum dimensions Height 1,420 mm x Wide 1,256 mm x Depth 1,309 mm.
Weight 77 kg for the BH1300-3-A coil-set.  See in below the weights of all the versions.
Accessories Delivered with Instruction Manual in English and Spanish. Assembly Instructions are included when it is delivered dismounted.
Warranty Two years.


  X pair (large) Y pair (medium) Z pair (small)
Effective diameter 1,295 1 mm 1,241 1 mm 1,187 1 mm
Number of turns (standard configuration)            (1) 144 138 132
DC Resistance, at 20 C                                       (2) 12.6 Ω  3% 11.6 Ω 3% 10.6 Ω 3%
Self-resonance frequency                                   (3) 2.7 kHz 5% 2.8 kHz 5% 2.8 kHz 5%
Self-inductance 160 mH  5% 141 mH  5% 122 mH  5%
Secondary field generated by the forms when used as coils (Xs, Ys, Zs)                                               (4) 1.39 T/A  1% 1.45 T/A  1% 1.51 T/A  1%

(1) - Its is possible to double the number of turns of each pair by changing the wiring at the terminal block .

(2) - Resistance measured at the general terminal block.

(3) - Self-resonance measured with -Xs connected to -X.

(4) - We call this constructive idea "In-Circuit Coil Forms".  - Click here for more details -


Version BH1300-3-A BH1300-2A-A BH1300-2B-A BH1300-1A-A BH1300-1B-A
Pairs of coils included X, Y, Z X, Y X, Z X Z
Weight, in kg 77 60 58 41 39
Minimum pathway width, in cm 130 130 122 90 122

- These specifications are subject to change without prior notice -


- Note about the internal transport of the coils: When the coil-sets are supplied mounted, the pathways in the building of destination should have the minimum widths shown in the table in above. When a coil-set can not be carried to its final location because some door or corridor is too narrow, it can be supplied dismounted, in which case will be attached detailed assembly instructions, in English and Spanish.

- There is a page in PDF format with views of the all the BH1300 versions, for 1, 2 and 3 axes.   - Click here to download this -


- This page in PDF format (for better print and spreading of this): - Click here to download this -

- BH300-3-A model page - click here -

- BH600-3-A model page - click here -

- To obtain this page in PDF format,click here -


For any enquiry, please, do not hesitate in contact us:

  Updated: 08 May 2014