Mastering The Tricky Job Of Soldering SMA Connectors

There’s a satisfaction in watching someone else at work, particularly when they are demonstrating a solution to a soldering problem you have encountered in the past. SMA panel sockets have a particularly tiny solder bucket on their reverse, and since they often need to be soldered onto brass rod as part of microwave antenna construction they present a soldering challenge. [Andrew McNeil] is here to help, with a foolproof method of achieving a joint¬†that is both electrically and mechanically sound.

The best connections to a solder bucket come when the wire connected to it nestles within its circular center. If this doesn’t happen and a blob of solder merely encapsulates both wire and bucket, the mechanical strength of the solder blob alone is not usually sufficient. The brass rod is wider than the bucket, so he takes us through carefully grinding it down to the right diameter for the bucket so it sits in place and can have the solder sweated into the gap. The result is very quick and simple, but has that essential satisfaction we mentioned earlier. It’s a small hack, but if you’ve ever soldered to a too-small RF connector you’ll understand. For more fun and games with RF connectors, take a look at our overview.

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Folding Robot

SMA Robot Jumps 7 Times Its Height, Weighs Nothing

This is some seriously cool research. Scientists at the EPFL (Ecole Polytechnique Federale de Lausanne) have made tiny, tiny,¬†tiny robots using shape memory alloys, or SMA’s for short. They weigh less than 4 grams and move like an inchworm!

Unlike regular robots that feature rigid structures and electric actuators, the researchers opted to take more of an origami like approach — so much so, they call it robogami. Their very first attempt was years ago, and was rather large. Since then they’ve shrunk it down to about the size of a compact flash card. The way it works is quite simple. SMA’s shrink when heated (either externally heated or by an internal current) and in doing so, produce extremely high forces.

So by patterning these in a shape (like that of an inchworm) the researchers are able to trigger each “limb” separately to induce movement. They can also jump seven times their height thanks to the super high power-density of SMA’s.

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Nokia Internet Key External Antenna

[Maurizio] was having some reception issues with his wireless internet and set out to add an external antenna to the USB dongle (translated). He had previously poked around inside of the Nokia internet key to find that the internal antenna was a flexible circuit substrate wrapped around a plastic box that made contact with main circuit board via a spring connector. This plastic frame is just right for mounting an SMA connector in just the right place for it to stick out the end of the case as seen in the picture above. It gives him better range, but since speed depends on how much traffic the wireless node is under, it’s not a guarantee that you’ll get a snappier connection after this hack.

How To Replace A Netgear Router Antenna

rp-sma-adapter-installed

a.ntivir.us wanted to use a different antenna for their Netgear mbr624gu WiFi router. Unfortunately, this model comes with an antenna that is not removable. As with other antenna retrofits, this involves no soldering. But because there is already a mounting area for an antenna, no case altering is needed either. After opening the router with a Torx driver it was discovered that the non-removable antenna was connected to the board with a mini rf connector (U.FL). The antenna and its mounting bracket were removed and a U.FL to RP-SMA adapter was put in its place using a washer to secure it to the rear plate of the router. Now any external antenna can be used and the router still looks brand new.

Breathing Walls With Shape Memory Alloy Wire

When you need something quietly bending or moving, don’t underestimate SMA’s (or Shape Memory Alloys). The Living Glass project by architects [David Benjamin] and [Soo-in Yang] catalogs an experiment in building interactive, flexible, “breathing”, walls out of SMA wire and microcontrollers. Although they use Basic Stamps, the project could easily be extended to more cost-effective microcontrollers for large surfaces. The project is well documented with videos (AVI) of each prototyping step and even includes the ideas that were ultimately scrapped. Even if you don’t build a wall of interactive gills, this project should give you plenty of ideas for uses of SMA wire embedded in semi-flexible materials.