Boston Electronics Corp. offers the model 442 digital lock-in amplifier from Scitec Instruments. It comprises a 100 x 160-mm PC board that can be used alone or embedded in an instrument. The amplifier is digitally controlled by a computer. It provides an operating frequency of 10 Hz to 100 kHz and accepts 3 mV to 10 V of input for full-scale output. The device, which operates in differential or single-ended mode, is suitable for OEM and laboratory use.