VPG – 1240 and 1260 Ultra high-precision bulk metal foil potentiometer range enhanced (1240 & 1260 Accutrim™ Trimming Potentiometers)

VPG’s improved VFR 1240 and 1260 Series of bulk metal foil ultra high-precision Accutrim trimming potentiometers feature low end-to-end TCR of ± 10ppm/C and ±25ppm/C through the wiper, load life stability of 0.1%, and <0.05% settability.

The devices are to meet and exceed the requirements of MIL-PRF-39035 Char. H. The approved 1/4-in square RJ26-style 1240 series, and 3/8-in square RJ24-style 1260 series devices operate from –55C to +150C.

The VFR 1240 and 1260 series of ultra high-precision trimmers feature a bulk metal foil resistive element that possesses a ‘unique’ inherent temperature and load life stability. Their advanced, virtually backlash-free (<0.05%) adjustment mechanism makes them easy to set quickly and accurately, and maintains that setting through temperature cycling and vibration, as well as thermal and mechanical shock. A further ‘unique’ feature of the VFR trimmer is its stability in the vibration environment, which eliminates the need for unwanted adjustments.

The devices offer a multi-fingered, noble metal wiper engaging a planar surface of etched Foil for low TCR end-to-end (five times tighter than required by MIL-PRF-39035 Char. H) and through the wiper. Other technologies, such as wirewound and cermet trimmers, have a fair TCR end-to-end, but cannot be relied upon to demonstrate an acceptable TCR through the wiper, which is an important element in the precise adjustment of circuits subject to temperature fluctuations.

In addition to their low TCR and excellent load life stability, the 1240 and 1260 trimmers feature a 0.1% typical setting stability, a wide resistance range from 5ohm to 10kohm, and standard resistance tolerances of ±5% and ±10%. The devices offer a 0.25W power rating at +85C and for increased reliability provide the utmost in ESD immunity, withstanding electrostatic discharges up to 25kV.

The devices provide unidirectional, infinite resolution, which when synthesized by a combination of an absolutely uniform resistance material, multiple wiper contact points, and multiple resistance circuit paths, yields a uniquely accurate settability of less than <0.05%. There are no turns of wire to be traversed, causing a step function, and no contact resistance variation to cause an irregular change in resistance with mechanical adjustment.

The 1260 devices offer tin/lead terminations, while the 1240 devices feature gold-plated terminations with tin/lead terminations on request. The 1240 and 1260 trimmers provide an O-ring to prevent ingress of fluids during any board cleaning operation, and are available with special options including special markings, burn-in, and screening operations.

Because of the stability and linearity of the foil trimmer it is not necessary to use a buffering resistor in series with the trimmer or a linearizing resistor in parallel with the trimmer. The low values available in foil trimmers are uniquely linear, making them suitable for end to wiper circuit use which is not normally recommended, says the company.

Purchase Now from one of the Distributors below

Digi-Key:

1240 Accutrim™ trimmer

1260 Accutrim™ trimmer

Farnell:

1240 Accutrim™ trimmer

1260 Accutrim™ trimmer

Mouser:

1240 Accutrim™ trimmer

1260 Accutrim™ trimmer