Digital input/output boards

Some commercially available boards integrate several of the above-described functions. For example the Metrabyte DAS8 board includes a 14-bit A/D converter with a multiplexed 8-way input, a D/A converter output, three digital inputs, four digital outputs, and two timers. 

An add-on industrial multifunction board - PCL 812PG with a 16-input 12-bit ADC, 16 digital inputs, 16 digital outputs. 

For the case labeled DC-DC Low-Power, we insert digital multimeters (DMMs) to measure the input and output current. We also connect DMMs directly across the input and output terminals of the converter board to measure input and output voltages. 

A multichannel analyzer (MCA) with a minimum of 4096 channels should be connected to a keyboard and display screen for input and output of data and interaction with a computer. Several kits are available for the conversion of personal computers (PCs) into MCAs. Basically there are three types of conversion kits. One makes use of board with an analogue-to-digital converter (ADC) that simply clips into the PC a second type uses a clip-in board with an external ADC and the third type uses a multichannel buffer (MCB) connected to the PC. All of these PC-based MCA systems are relatively inexpensive and are very suitable for use in germanium and sodium iodide y-ray spectrometry. 

The electrical potential of the reaction mixture is measured with a platinum electrode and a Hg/Hg2S04 reference (available from Rainin). The output can be recorded on a single-channel strip chart recorder, with the platinum electrode attached to the positive terminal and the reference to the negative, or the recording can be made via a high-impedance input to an A/D board (analog-to-digital converter) on a computer (see Chapter 3). 

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