IEEE-488 bus compatible computer interface for an EPR spectrometer

An inexpensive, versatile computer interface for a Varian E109 spectrometer has been realised. This interface, which is constructed using low cost and easily available electronic components, is able to communicate actively (listen and talk mode) with the host computer through the IEEE-488 standard bus. The hardware of the interface provides a means for: controlling the magnetic field without any manipulation of the spectrometer field controller; recording, in a digital form, the EPR analogue signal; and plotting any computer synthesised and/or stored spectrum on the EPR X-Y recorder. All the hardware diagrams and a summary of the data acquisition and processing software are presented.