BCS-10 balanced current source module

This module provides programmable currents from 1 pA to 100 mA with a ±10 V maximum compliance output from DC to 100 kHz sinusoidal output. Derived from Lake Shore’s industry-leading Model 372 AC resistance bridge, the BCS-10 employs a differential or balanced design that helps reduce or eliminate ground loops often encountered in cryostats and other research apparatus. It expands on Model 372 balanced source capability, adding variable frequency and amplitude programmability for enhanced flexibility while maintaining excellent noise performance.

The inclusion of a virtual center-point ground connection further enhances noise performance by allowing the user to determine optimal center-point tie points within given apparatus or equipment setups. The BCS-10 is designed to be paired with the VM-10 module, which provides both single-ended and differential (balanced) input connection and modes. The true differential (balanced) wiring configuration minimizes noise coupled from the environment, such as from power lines, lighting, motors, and other lab equipment.

A typical application of the balanced current source involves low-resistance measurements, where the resistance of the wires connecting the current source to a sensor may be significant. Any imbalance in lead wire resistance results in a common-mode voltage that complicates the measurement of the desired parameter, the voltage across the sensor. The external CMR feature is unique in that it allows the BCS-10 to force some remote node (such as a VM-10 input) to circuit common potential and thus mitigate the effect of unbalanced lead wire resistance.

BCS-10 specifications

Specifications subject to change

Ranges: 100 mA, 10 mA, 1 mA, 100 μA, 10 μA, 1 μA, 100 nA, 10 nA; automatic selection

Compliance: 20 V differential, 10 V single-ended (non-settable)

Maximum power: 1 W, 4-quadrant operation

CMR modes: Off, internal, external

Coupling: DC or AC (1 Hz)

Guard drive: Enable or disable

Rise time: <25 µs, 10% to 90%, zero to full scale, <1 Ω impedance load, 1 µA and above ranges

Settle time: <60 µs to 0.1% of final value, zero to full scale, <1 Ω impedance load, 1 µA and above ranges

Load impedance: Stability maintained with reactive loads up to 50 µF or 1 mH (with 100 Ω damping)

Magnetic field exposure: Operational up to 11 mT DC

Size: 142 mm W × 39 mm H × 89 mm D (5.6 in × 1.5 in × 3.5 in)

Options for the BCS-10 module that you can set on the M81 instrument screen