No matter how small you make your embedded projects, you still need a way to program the MCU. Standard programming headers can be annoyingly large for those very small projects. [Danny] wrote in to tell us how we can save room on our PCB designs using special spring loaded connectors, rather than large headers.
There are so many small embedded development systems, such as the Trinket that still rely on standard headers. Reducing the size of the programming headers and interface headers is an issue that deserves more attention than it currently receives. Based on Tag-Connect, a proprietary connector built around pogo-style pins, your PCB does not actually require any on-board mating connector. The PCB footprint simply has test-pads that connect with the pogo-pins and holes that allow for a rock solid connection. While the Tag-Connect header is a bit expensive (it costs about $34), you only need to buy it once.
It would be great to see even smaller Tag-Connect cables. Do you have a similar solution? What about something even smaller and more compact? Write in to tell us about any ultra-compact connector solutions you have been using!
[Chris] over at the 23B hackerspace had a bit of a problem – a project required the use of a very old rotary encoder with a mil-spec connector. While it might be possible to simply buy one of these mating connectors on Digikey or Mouser, that’s not [Chris]’ usual MO. He has a nice 3D printer, and this connector is basically a cylinder with some holes. How hard could printing out one of these connectors be?
The dimensions for [Chris]’ first attempt at creating a mating connector came from Solidworks’ “Sketch Picture” command where an image can be superimposed over a model and the 3D features created from that guide. If it worked, it would be far too easy, and the printed model didn’t fit at all.
This failure led [Chris] to page through MIL-STD-1651, a portly tome of 200+ pages covering every circular connector possible. After 20 minutes of scanning the specs, [Chris] found what he was looking for: the correct specification showing him where all the pins and holes should go.
After some fine modeling in Solidworks, [Chris] had his very own custom printed Mil-Spec connector. Sure, he ate up more time than it was worth for one connector, but now that he has the STL file, he can print out as many as he needs.
Etching and populating a board is childs play compared to finding connectors which link several components. But Hackaday alum [Ian Lesnet] and his crew over at Dangerous Prototypes have come up with a solution that makes us wonder why we haven’t seen this long ago? They’re prepping an any-size ribbon cable kit.
So lets say you do find the type of connector you want. You need to cut the ribbon cable to length, crimp on the connectors, then seat those connectors in the housing. We’ve done this many times, and being cheapskates we use needle-nose pliers instead of buying a proper crimper. This solution does away with that grunt work. The kit will ship several different lengths of ribbon wire with the connectors already placed by machine. This way you peel off the number of connectors you need, select the proper house size and plunk it in place. Also in the kit are several lengths of male, female, and male/female jumper cables you can peel off in the same way.
Now what are we going to do with the rest of the spool of ribbon cable sitting in the workshop?
It’s not uncommon in cheaper devices to find a ribbon cable soldered directly to the circuit board like the one pictured above. Using a connector would have been a much more resilient approach, but adding parts adds cost. If you take a close look you’ll see things aren’t looking so great anymore. [Chaotic and Random] pulled this board out of his VW Camper Van. Rather than buy an expensive replacement part, he shows us how to repair a soldered ribbon wire connection.
This repair is rather invasive and he suggests trying some hot-air rework (possibly using a heat gun) to fix up any misbehaving connections. But if that has failed it’s time for the knife. The first step is to cut the ribbon so that the LCD can be removed from the board. From there he peels the remaining scrap off ribbon of the pads. This makes us cringe as it could lift traces from the PCB, but he was gentle enough to avoid it. Now comes the time to start reassembling. After thoroughly cleaning the pads the ribbon is cut straight and resoldered. The trick is to flow the solder without melting the ribbon. He uses tin foil to cover the tip and cools it on a moist sponge just before reflowing solder.
It sounds like more art than science. But when the only alternative is to spend hundreds on a new part it may be worth a try.
Standard connectors in portable devices would be great for the consumer, but then you wouldn’t purchase separate peripherals for ever portable you buy (lining the pockets of the companies licensing said peripherals). [Thijs] isn’t taking it lying down any longer. Realizing that the shape of the connector is one of the only things standing in the way, he built an adapter to use iPod docks with Droid. The hardware consists of a USB connector, audio jack, iPod connector, and a magnet. After working out the wiring it was just a matter of building a chassis using polymorph material. As you can see above, his expensive dock has no problem playing nicely with Droid because of his handy work.
Chances are you’ve come across an Ethernet cable where the small plastic tab that holds the plug in place has broken off. We have a crimper on hand and usually just throw on a new RJ45 connector but [Laxap] found a simple alternative to fix Ethernet plugs. By using a couple of correctly sized cable ties you can secure the damaged connector without replacement. The boxy locking mechanism on the end of the cable tie is used as the catch, slimmed down with the help of an X-Acto knife or razor blade. Once you’ve got the right fit, use a second cable tie to secure it to the Ethernet cable. Simple is brilliant.