The ALD MB1S is a precision +/-5½-digit Digital Voltmeter (DVM) printed circuit board that contains the ALD500R/ALD521D A/D Converter chipset that directly plugs into the parallel printer port of a PC computer. It features calibrated analog input (w/scalable input ranges), and digital circuitry to communicate with PC or other microprocessors. It is designed to be used as a stand-alone, embedded system component in a variety of applications including digital panel meters, customized instrumentation displays, temperature monitoring, high resolution DVM’s, weigh scales and others. Direct Full-scale analog input range is +/-2.00000V DC with a linearity of 0.005%. ALDs 18-bit plus sign integrating dual-slope analog processor (ALD500) functions as the input device and the ALD521D microprocessor IC implements the digital conversion, control mode and I/O functions.

Hardware and Software Features
● Directly plug into a PC parallel printer port and displays readings on the monitor.
● Measurement Range: +/-2.00000V DC direct input.
   (Other ranges are user configurable and scalable, using both hardware and software scaling)
● Self-powered from PC computer or external +5V DC power source
● All solid-state construction.
● 24-bit serial output. (23-bit plus sign bit)
● User selectable +/-3½ to +/-6½ digits.
● Differential analog inputs with auto-polarity and auto-zero.
● Simple to install and operate.
● Calibration for positive and/or negative inputs.
● Provision for input voltage scaling attenuator network.
● Smart Input Filtering (Sample Averaging) selection for noise reduction and accurate displays.
● Optional MS-DOS software for user operation, setup, and calibration is sold separately.

Key Specifications
MB1S (MB1SA2V)
● Direct Full Scale Analog Input Range: +/- 2.00000V DC
● Input Impedance: 1GΩ min, 100GΩ typical.
● Optional on-board input resistor divider network for wide input voltage ranges
● Resolution: +/- 1 digit, (+/-10µV) @ Vin = 1.00000V (16x input averaging)
● Overvoltage Protection: 20V DC
● Conversion Sample Rate: 3-samples/sec (from 1 sample/min. to 10 samples/sec.)
● No external power source necessary, draws power directly from the PC printer port
● Optional external Power Supply: +4.5 to +5.5V max @ 6mA max.
● Accuracy +/-0.01% (After 2 hour warm-up)
● Linearity +/-0.005% full-scale (23º C, +/-1º C).
● Logic Compatibility: CMOS inputs and outputs.

MB1SA20V
● Direct Full Scale Analog Input Range: +/-20.000V DC
● Input Impedance: 10MEGΩ nominal
● Optional on-board input resistor divider for wide input voltage ranges
● Resolution: +/-1 digit, (+/-100µV) @ Vin = 10.0000V (16x input averaging)
● Overvoltage Protection: 200V DC
● Conversion Sample Rate: 3-samples/sec (from 1 sample/min. to 10 samples/sec)
● No external power source necessary, draws power directly from the PC printer port
● Optional external Power Supply: +4.5 to +5.5V max @ 6mA max.
● Accuracy +/-0.02% (After 2 hour warm-up)
● Linearity +/-0.01% full-scale (23º C, +/-1º C).
● Logic Compatibility: CMOS inputs and outputs.