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The Smart Tweezers get smarter

Kenneth Wyatt- September 10, 2012

For years, I’ve looked for an affordable LCR meter to measure unknown components–especially surface-mount. I ran into the Smart Tweezers (Model ST3) a couple years ago and wrote up a short review. Since then, Canadian company Advance Devices, has updated the design (Model ST5). This model is very similar, but there are a number of improvements worth mentioning.

Most LCR meters make basic measurements, but with limited ranges or inadequate accuracy. The ST5 is calibrated to NIST standards and includes a Certificate of Calibration. In addition, most conventional LCR meters aren’t really optimized to measure today’s SM (surface-mount) components. It’s tough enough working with SM parts...let alone trying to identify them once a few parts on your workbench get mixed together.

While the ST5 was designed primarily for measuring surface-mount components, I noticed the tip arms have been spaced further apart than those on the earlier model. This will allow the tips to be spread apart easier for measuring leaded components.

In a significant improvement, The ST5 uses a Li-ion rechargeable battery instead of hearing aid batteries. That was a major drawback to the previous version. Because it was never truly “off,” it would deplete the batteries, whether you used the meter, or not. The ST5 may be charged from any USB port or by using the supplied 5-V charger.

Other improvements include the redesigned joystick controller. The previous ST3 had a two-way and push controller on the side, which was a little difficult to control, as it was hidden. The new ST5 has a four-way and push controller “joystick” on top of the handle where you can see it. In addition, the ST3’s side controller had a rather sharp nubbin that would cause irritation when pressed repeatedly. The new version has a more blunt nubbin that is easier on the finger (Figure 1).


Figure 1. An overall view of the new model Smart Tweezers with major features labeled. (Photo courtesy Advance Devices.)

This instrument goes far beyond the norm for LCR meters. It actually measures both the real and imaginary impedances. What this allows the microprocessor-based instrument to do is measure and read out not only the resistance, but series inductance - - not only capacitance, but ESR (equivalent series resistance) or D - - not only inductance, but DC resistance or Q. The new model also includes a new diode test mode that will indicate polarity and shorted devices. New also is a continuity beeper. The new ESR mode will help you measure the ESR of high-value capacitors at various frequencies.

Because the generator voltage is now adjustable in steps from 0.20 V, 0.50 V and 1.0 V, it more accurately measures in-circuit devices without turning on semiconductor junctions. This variable applied voltage improves accuracy in measuring the CK05 and CK06 ceramic capacitors, whose capacitance varies with applied voltage. There is also a visible and audible “tolerance mode” that helps sort components. Finally, you can store a pre-programmed offset, which improves measurement precision for low-valued components. In other words, you can null out the effect of the tweezer handles and associated tip-to-tip capacitance or series inductance.


Figure 2. Close-up of the LCD screen showing the main measurement (larger) and secondary measurement (smaller). The built-in generator voltage and frequency, as well as the circuit model used is also displayed. (Photo courtesy Advance Devices.)

OK, so what do you get for your $387? The basic unit comes with a multi-voltage power adapter and mini-B USB charging cable. The tips are the straight-style gold-plated version crafted in Switzerland and very sharp. It also arrives in a padded plastic storage box. The gold-plated tips are replaceable and replacement standard or bent tips are priced at $40. Premium tips that are tested to handle surface-mount devices down to 0201 size are also available for $60. Table 1 highlights the specs.

Table 1. Basic Specifications