Build a stereo microscope from binoculars and a camera lens

April 27, 2012 By Leave a Comment

Here’s an oldie but a goodie. [RunnerPack] stumbled upon an article from 2001 about building a stereo microscope from a pair of binoculars and a camera lens. With a ring light attached to the end of the camera lens, we couldn’t think of a better microscope for SMD work.

To mount the binoculars to the camera lens, [Giorgio Carboni] made a very nice adapter containing four prisms. These prisms are very carefully aligned and glued down with a little bit of epoxy. By using an 8×30 pair of binoculars and a 35-100 mm camera lens, [Giorgio] was able to get a magnification factor of 10-57x. With a macro lens this factor can be increased (a 28mm lens bumps it up to 71x, but a lot more light is needed).

The pedestal is just a few ground rods and ground steel rods, something that requires a bit of machining. Since 2001, though, a lot of tinkerers have 3D printers so it could be possible to build a more easily manufactured version of the focusing apparatus.

[RunnerPack] had a pair of binoculars and a camera lens handy and tried a mono version of this build. He says he was blown away, but unfortunately didn’t provide any pictures. If you decide to build this project, be sure to snap a few pics and send it in on the tip line.

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SMDuino helps Arduino fit into tight places

March 23, 2012 By Leave a Comment

[Adam] was tired of plopping the same components over and over into his Arduino-based designs. He spent part of his weekend laying out a small board that would host everything he needed and could be built as a single component for all future projects. Above you can see the project he calls SMDuino, an Arduino clone that can be used as a surface mount part.

The contacts on four sides of the board break out the pins. They’ve been designed with 0.1″ pitch which means they will work with standard pin headers. But since they’re plated through from top to bottom they are easy to solder to surface mount pads as well. The project is open source, so you can order your own boards (he used DorkBot PDX) or email him if you want to get in on a pre-order. That is for unpopulated PCBs only. But there’s few components used here so it’s pretty inexpensive to throw together. You’ll need four caps, four resistors, a crystal, an LED, the ATmega*8 of your choice (an ATmega328 is used here), and a low dropout regulator. Of course it is possible to go without the crystal oscillator.

Does this remind anyone else of the Basic Stamp 2?

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Fine-pitch SMD soldering with minimal tools

March 13, 2012 By Leave a Comment

We try to stick to the 0805 parts because they’re still big enough to solder by hand. But [Scott] shows us that it doesn’t take too many special tools to reflow fine-pitch components at home. In this case he’s using 0402 resistors, a footprint that we consider functionally impossible to solder using an iron.

The two parts of the equation that he spent some money on are professionally produced PCBs and a solder stencil. The stencil is laser-cut from Kapton, which is heat-resistant so it doesn’t warp during the cutting process. An acrylic frame holds the PCB in place, and he just tapes the stencil over it and uses a chunk of acrylic as a squeegee to evenly apply the solder paste. Splurging on the PCB and stencil means you’ll achieve tolerances which lead to success.

The next issue is placing the components. [Scott] shows off some vacuum tweezers he built using an aquarium pump. Watch the video after the break to see how small those 0402 parts are when he extracts one of the resistors from the tape packaging. With the board manually populated (check everything twice!) he moves the board to a completely unaltered toaster oven for reflow. We have seen a lot of projects which add controllers to these ovens, but he really makes the case that you don’t need it. Instead, he uses a thermocoupler read by a multimeter just to let him know what’s going on with the temperature. He uses a smart phone as a timer, and switches the oven on and off to match the solder’s heat profile. [Read more…]

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Toaster oven reflow soldering roundup

March 8, 2012 By Leave a Comment

SMD components have a lot of advantages over the through-hole parts our fathers and grandfathers soldered. Working with these tiny surface mount components requires a larger investment than a soldering iron and a wire-wrap gun, though. Here’s a few reflow ovens that were sent in over the past week or two.

[ramsay] bought a 110 V toaster oven off of eBay. Even though [ramsay] is in England and has 230 V mains, everything in the oven is mechanical and works just fine with a higher voltage. His first test didn’t go quite as planned; the solder paste wasn’t melting at 120° C, so he cranked up the temperature and learned that the FR in FR-4 stands for flame retardant. Never deterred, [ramsay] decided to build a controller so the temperature ramps up and cools off at the right rates for the flux and paste to do their thing.

Solder paste has a temperature profile that requires the board to be kept at a temperature between 150° and 180° C for a minute or so before climbing up to 220° for a second so the solder will melt. [Nicolas] had the interesting idea of putting a USB port in his toaster oven and storing the heating profiles on his desktop. The build uses an MSP430 microcontroller to turn the relays powering heating elements on and off. [Nick] is working on a C# desktop app to monitor and regulate the oven temperature from his computer, so we’re fairly interested in seeing the final results.

Watching the SMD self-alignment videos on YouTube is a lot more fun than messing around with tweezers, stereo microscopes, and extremely fine soldering irons. If you’ve got a better idea for a toaster/reflow oven, send it in on our tip line and we’ll check it out.

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