Measuring SMD Parts With A Home Brew Version Of Smart Tweezers

November 7, 2012 by Brian Benchoff 22 Comments

SMD parts are great; they allow you to pack more parts on a board, do away with drilling dozens of PCBs, and when done correctly can produce a factory-quality board made in a home lab. There’s one problem with SMD parts; troubleshooting and measuring them. The ideal solution would be something akin to the Smart Tweezers we’ve seen before, but this fabulous tool costs three hundred bones. [Kai] came up with a much cheaper solution: home brew smart tweezers that can be built for a tenth of the cost as the professional model.

What [Kai] built is an LCR meter, basically a tool that measures inductance, capacitance, and resistance in a very, very small form factor. The technique of measuring a part’s properties involves feeding a set frequency into the device and measuring the phase, voltage and current coming out. It’s all wonderfully explained by [Dave] over at EEVblog in one of his earlier videos.

The hardware [Kai] is using includes an LCD display from a Nokia phone, an MSP430-based microcontroller, a very tiny opamp near the tip of one of the points of the tweezer, and a programmable gain amplifier used to measure the components. In testing, [Kai] can measure very low-value components with a +/- 2% accuracy, and larger, more realistic components with +/- 0.25% accuracy. An awesome accomplishment, and much better than the common Chinese meters that can’t measure in the nH/pF/mΩ range.

[Kai] hasn’t gotten his pair of smart tweezers working yet – he still needs to get the circuit up and running and write some software. We’ll keep our readers apprised of [Kai]’s progress, though, and gently convince him to work with Seeed Studio or someone similar to get his version of Smart Tweezers onto maker’s workbenches the world over.

Multimeter Add-on Lets You Measure Tiny Resistance Values

June 15, 2012 by Mike Szczys 15 Comments

This multimeter add-on is called the Half Ohm. It allows you to measure small resistance values, and can be used to track down shorts on a PCB.

The board acts as a pass-through for both probes. When your meter is set to measure voltage and nothing is connected to the probes the display will read out the level of the coin cell that powers the add-on. When you are probing, the value in millivolts is actually showing the resistance in milliohms. This works for any measurement less than one Ohm. Interestingly enough, it will help you zero in on a solder bridge. By probing the two shorted tracks you can find the issue by following the falling resistance values.

[Jaanus] published several posts leading up to the final version of the board. Check out this category link for his blog if you’re interested in reading through them.

DIY Smart Tweezers Make SMD Work A Cinch

August 10, 2011 by Mike Nathan 22 Comments

diy_smd_smart_tweezers

[Noel] does a lot of SMD work and wanted a pair of “smart” tweezers that could be used to place components as well as for reading their capacitance and resistance values on the fly. As we have seen, these things can be somewhat costly, and not really necessary if you already have a good multimeter. With that in mind, he figured he could build his own for almost nothing.

He started off with a pair of kids’ “training” chopsticks which are durable, but more importantly, non-conductive. He took a second pair of tweezers, this time made of metal, and split them in two. He soldered wire to a set of ring terminals, mounting one on each leg of his broken tweezers. The final bit of assembly involved using zipties to mount everything on the plastic chopsticks along with the addition of banana plugs to the end of his probes.

[Noel] says that the tweezers work quite well, and with such a low price tag, we can’t argue.

Variable Capacitance/reistance Switch Box Has You Covered

April 13, 2011 by Mike Nathan 11 Comments

variable_cap_resistor_box

While working on electronics projects, it’s often necessary to test out different capacitance or resistance values as things are moving along. Depending on what you are testing, this can be a tedious process even when using a breadboard. Instructables user [mattthegamer463] recently built a very useful device that would help out in these situations, and would likely be a welcome addition to any Hackaday reader’s workbench.

His variable resistor/capacitor box makes it easy to test out any number of different resistance or capacitance values with a simple turn of a knob. He wired up a pair of pots to provide a wide range of resistance values, being sure to add a low-resistance safety as well as safety override switch for those of you who like to ~~have things blow up in your face~~ live dangerously. A set of 22 capacitors were wired up on a piece of perfboard, each of which can be selected using a pair of knobs. He added a simple switch to allow the capacitors to be toggled between parallel and series orientations as well.

[Matt] did a wonderful job here – this is a great project that can be customized in a multitude of ways to fit almost anyone’s specific needs.