Digital Multimeters of TTi
Choosing the Digital Multimeter

Bench-top DMMs versus hand-held
Low cost hand-held DMMs have replaced bench-top DMMs in many applications. Although the performance of these meters may be sufficient for some tasks, it is likely that most engineers will regularly encounter measurement problems that are beyond the capability of a hand-held unit.

An instrument intended for serious use
A TTi bench-top DMM is a substantial instrument. It stays where you put it even with heavy test leads connected. The multi-position tilt stand ensures that the large display is always readable. The functions buttons are large and the front panel is clearly marked.

Sensitivity, Resolution and Accuracy
Compare the performance of any TTi bench-top DMM with a good quality 4000 count hand-held DMM of 0.3% basic dcV accuracy.
Longer scale length, greater sensitivity and higher accuracy ensure that measurement uncertainty is a full order of magnitude better. TTi bench-top DMMs maintain good accuracy on all functions including ac voltage, resistance and current. For most hand-helds, the accuracies for functions other than dc voltage are dramatically poorer.

Wideband ac measurement and true RMS
Most hand-held DMMs have an ac frequency response specified to below 1kHz. All TTi bench-top DMMs provide excellent accuracy on all ranges throughout the audio band (40Hz to 20kHz) with a 3dB bandwidth extending well above this. Most ac signals are not sinusoidal. However, most hand-held DMMs incorporate a mean sensing ac converter which only gives useful results on sinusoids, those that do have a True RMS converter often have insufficient bandwidth to cope with complex waveshapes. All TTi bench-top DMMs combine True RMS ac with sufficient bandwidth to ensure accurate results.

PC and System connectivity
At some point most engineers are going to want to connect their DMM to their personal computer to provide automatic measurement control or importing of data into a computer programme. Unlike a hand-held DMM, all TTi bench-top DMMs include a fully isolated RS-232 interface. For full system applications, the 1705-GP also have a GPIB (IEEE-488) interface.

Functions & features of real value
TTi bench-top DMMs offer features which are of real use and not just “gimmicks”. Features such as dual Measurement & display, precision frequency measurement, dBm, data logging, power and VA, to mention just a few. Hand-held DMMs may offer a few “smart” features but these are rarely well enough implemented to be of real use.

A range to cover most needs
The TTi range of bench-top multimeters consists of three models. All incorporate automatic or manual ranging, true RMS ac measurement, and interfaceability using RS-232 or GPIB (IEEE-488) depending upon model. The 1604, 1705 and 1705-GP are ac mains powered units. The 1705 can be operated from either ac mains or from batteries.



New Series of Digital Multimeters of Transmille

The 8000 series Digital Multimeter with 7.5 or 8.5 digits provides outstanding accuracy and linearity measurement performance together with ease of use.
The heart of any precision instrument is in its analogue design; the experience and knowledge gained by Transmille over 10 years in the development of its 3000 series precision multi-product calibrators, its innovation and commitment to quality have all been directed towards the design of the 8000 series multimeter.
The choice of components is critical in the design, the 8000 series using precision foil resistors, with temperature coefficients less than 1ppm°C and the latest in analogue chopper stabilised op-amps and low leakage switches. A temperature stabilised zener reference chip provides 1ppm stability/year. PCB design at this level is critical, and every effect from thermal EMF's to leakage must be eliminated if 8.5 digit performance is to be achieved.

To give stable readings in noisy environments the 8000 Series measurement cycle is phase-locked to the mains (line) power. To complement the analogue design the 8000 series multimeter digital design is also state of the art. The 8000 series is a multiprocessor design, making full use of today's low cost digital processing power. Low-level processors handle the measurement ranging and A to D control etc, while a single chip 64 bit high performance processor handles data management. Circuitry, which would have just a few years ago taken up complete circuit boards, is now available on a single chip, improving reliability, reducing power and also cost, whilst at the same time improving performance. By bringing together the latest technology in both analogue and digital design Transmille have significantly reduced the parts count and the complexity of an 8.5 digit multimeter, achieving unrivaled performance at a breakthrough price.The 8000 Series DMM complements the 3000 Series range of multi product calibrators, 3200 electrical test equipment calibrator and the 30000 Precision range of reference standards. This comprehensive range of Queen’s award winning instrumentation combined with the ProCal calibration software provides a complete solution for the modern calibration laboratory.