The BMA-200 is a low-noise, portable, battery operated amplifier for EEG, ECG, EMG, and other extracellular applications. The BMA-200 features a wide gain range, sharp cutoff bandpass filters, an AC calibrator, and a built-in audio amplifier and speaker for monitoring the signal. Stimulus delivery to the electrodes is accomplished by a front-panel switch, or via an external logic signal. True DC response is switch-selectable, with a variable DC offset control. Low-power circuitry contributes to long operating time between charges, or the unit can be operated continuously with the included AC adapter. It can be used as a stable DC amplifier, and includes adjustable DC input offset controls. Positive and negative DC voltages are provided at the input connector for bridge excitation or powering optional head-stage active probes. For human subject recording, the ISO-Z Isolation Amplifier head-stage should be used. Active probes are available for high-impedance microelectrode applications. The BMA-200 is fully compatible with the complete line of cables, electrodes, and other accessories available for the BMA-931 modular amplifier. The BMA-200 is the latest in our line of high-performance preamplifiers. Its versatility and wealth of features make it equally at home in the laboratory or as a rugged field instrument.