AD232 converter

The well-known ICL7106 A-D converter IC has been with us in many generations of digital multimeter. A special version of it, the ICL7109, ofters the same accuracy, comes at a low price also, but sports a parallel interface instead of a 7-segment driver. The ICL7109 requires only a handful of components to build a versatile measuring box with an RS232 interface that is easy to manage thanks to so me hardware tricks. Software for IBM PCs and compatibles is available to control this unit, wh ich is basically a multiplexed A-D converter with an RS232 interface.