Tools: Smart Tweezers

We’re big fans of surface mount parts. SMD components are cheaper, take less board space, and don't require drilling; all the coolest new parts are only available in SMD packages.

Smart Tweezers are an advanced multimeter tool specifically designed to test and troubleshoot SMD circuits. It automatically identifies resistors, capacitors, and inductors, and displays the relevant measurements. Advanced Devices sent us a pair of Smart Tweezers to review. We used them while building our last few SMD projects, read about our experience with this tool after the break.

Smart Tweezers are a multimeter that measures resistance, capacitance, inductance, and voltage with tweezer-like probes. The probes are shaped to hold loose SMD components, or test components already soldered to a PCB. Measurements are displayed on a small graphic LCD that reverses for left or right hand use. If you’ve ever tried to measure SMD components with a typical multimeter, the value of the tweezer profile is immediately apparent.

Starting at $300, this tool is intended for professionals who regularly debug, test, or repair SMD electronics. It's a bit out of reach for a hobbyist who just wants to salvage SMD parts.

We tested the Smart Tweezers while developing three recent SMD projects: the DIY digital picture frame, the Bus Pirate version 1, and an upcoming ethernet device. It's a real headache to debug an SMD circuit with typical multimeter probes: balance the probes on the correct pins, ensure that the probes don't create momentary contacts that aren't due to soldering, and then hold this position long enough to get a good measurement. This only gets worse if you have to repeat several times. The Smart Tweezers test SMD components with a quick single-handed squeeze.

The Smart Tweezers’ graphic menu is navigated with a simple jog wheel. The tool turns on with a press of the jog wheel, and turns off automatically after an adjustable timeout. The default auto-measurement mode attempts to detect the type of component and chooses the best properties to display, but auto-mode is a bit slower than setting a specific measurement mode.

Resistance

Every multimeter measures resistance, a typical multimeter has several test ranges that are toggled manually. The Smart Tweezers measure resistor values between 0.1Ohm and 5MOhms, without manual range adjustments. In the photo we’re measuring a 390ohm, 1% resistor.

Capacitance

Capacitance measurement is a feature that's found on some high-end multimeters. The Smart Tweezers measure capacitance between 10pF and 499µF. In the photo we’re measuring a 27pF, 5% capacitor commonly used in a crystal oscillator.

A measurement taken from a single capacitor shows its value. A measurement taken from a circuit board shows the total capacitance of all connected components and of the PCB itself.

Inductance

Inductance measurement is rarely found on a multimeter. The Smart Tweezers measure inductance between 1µH and 1H. We didn't have an SMD inductor to measure, but we tried a through-hole inductor coil from a switch mode power supply.

Voltage

The Smart Tweezers also measure up to 8volts AC or DC. After navigating to the voltage mode, the Smart Tweezers beep until you flip a small, recessed switch in the side of the case. The switch is too recessed to flip with a fingernail, so we used a through-hole resistor lead.

In the photo we’re doing a quick check to make sure that a tiny SOT-23 LTC2631a digital to analog converter is properly soldered to an adapter board and receiving power.

Continuity/Open Test

The Smart Tweezers have a continuity checking mode that beeps to verify connections between parts. This is an easy way to make sure every leg of a large SMD chip is properly soldered, or to hunt for broken/damaged components.

Current

The Smart Tweezers don't directly measure current consumption, but it's easy to calculate using voltage and resistance measurements with the equation Ir=Vr/R.

As with any tool, we can't help but take it apart and see what's inside.

The batteries are replaced by removing three screws and the front cover of the device. This view reveals the batteries, the LCD screen, a small piezoelectric speaker, and the back of the circuit board.

A single screw in the back of the case holds the circuit board in place. We removed the screw to expose the front of the circuit board. The Smart Tweezers are powered by a Texas Instruments MSP430F135 microcontroller and a half-dozen analog chips. The MSP430 line is well-known for low power consumption, and it's a logical choice for a portable device. Most of the passive support components are size 0402 or smaller.

The Smart Tweezers saved us a lot of time constructing and debugging three surface mount electronic designs. A simple squeeze and test is much faster and easier than awkwardly probing tiny parts with our cheap multimeter. It's so much easier, in fact, we could hold the Smart Tweezers with one hand and take all the photos in this article with the other; try that with a normal multimeter.

We think two small changes could make the tool even easier to use. First, a larger button would make it easier to switch to voltmeter mode without a wire or screwdriver. Second, it would be really nice if it could be turned-on by squeezing the tweezers together, rather than pressing the jog wheel.

We really liked the automatic component detection and auto ranging, and the measurement speed is excellent. We appreciate that the tweezer tips are replaceable because we’re really hard on our tools.

If you’re a professional or student who does a lot of work with SMD electronics, a pair of Smart Tweezers can save you time by reducing awkward multimeter measurements to a simple squeeze. This fairly expensive tool is probably overkill for all but the most hard-core hobbyists, but if you derive income from electronics, like we do, Smart Tweezers can be really handy.