Turning A Rubidium Standard Into A Proper Tool

August 5, 2013 by Brian Benchoff 42 Comments

You can find rubidium frequency standards all over eBay and various surplus dealers. They’re actually quite interesting devices, able to generate a 10 MHz sine wave with enough precision to be a serviceable atomic clock. While these standards can find themselves very useful in a lab, they’re only a component, and not a working-out-of-the-box device. [Gerry] decided he would fix that, turning his rubidium standard into a proper piece of bench equipment, all in a single afternoon.

[Gerry]’s first step was finding a proper enclosure for his new piece of equipment. Most of the time, choosing an enclosure is practice in the art of compromise. This time, though, [Gerry] found the perfect enclosure: an old piece of video distribution equipment. On the back of this box, there are a ton of BNC plugs, perfect for attaching to random lab equipment and feeding them a signal from the rubidium standard.

After going through the video circuit and changing the 75 Ohm outputs to 50 Ohms, [Gerry] wired up an eBay power supply, fan, and a small circuit with an 8-pin PIC to complete his new tool. The rubidium standard does get freakishly hot, but hopefully mounting it to a large aluminum box with a bit of cooling will keep all the added electronics in working order.

[Gerry] did all this in just under 5 hours. An impressive feat, given that he probably spent that much time editing the video, available below.

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Measuring Tiny Current With High Resolution

August 4, 2013 by Mike Szczys 27 Comments

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[Paul] knew that he could get an oscilloscope that would measure the microamp signals with the kind of resolution he was after, but it would cost him a bundle. But he has some idea of how that high-end equipment does things, and so he just built this circuit to feed precision data to his own bench equipment.

He’s trying to visualize what’s going on with the current draw of a microcontroller at various points in its operation. He figures 5 mA at 2.5 mV is in the ballpark of what he’s probing. Measurements this small have problems with noise. The solution is the chip on the green breakout board. It’s not exactly priced to move, costing about $20 in single quantity. But when paired with a quality power supply it gets the job done. The AD8428 is an ultra-low-noise amplifier which has way more than the accuracy he needs and outputs a bandwidth of 3.5 MHz. Now the cost seems worth it.

The oscilloscope screenshot in [Paul’s] post is really impressive. Using two 1 Ohm resistors in parallel on the microcontroller’s power line he’s able to monitor the chip in slow startup mode. It begins at 120 microamps and the graph captures the point at which the oscillator starts running and when the system clock is connected to it.

Drilling PCBs With Cameras And Math

August 4, 2013 by Brian Benchoff 17 Comments

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After making your first PCB, you’re immediately faced with your next challenge – drilling the holes. It’s a doable task with a small drill press, but a lot of makers already have a small CNC mill or router, but how to make that work the first time? [Alessio] has you covered with a technique that uses a CNC-mounted webcam and some linear algebra for perfect through-holes the first time and every time.

A few months ago we saw [Alessio]’s work with transform matrices and PCB drills. The reasoning behind this technique is if a PCB isn’t exactly aligned to a CNC mill’s axes, or if the scaling for a toner transfer board is a bit off, automating the drilling process will only end in pain, with holes going through traces and a whole host of other nasty things. The application of linear algebra gets around this problem – taking a measurement off of two or three known locations, it’s easy to program a CNC machine to drill exactly where it’s supposed to.

[Alessio]’s new project takes the same mathematical techniques and applies them to a very sleek application that uses a drill-mounted webcam. After taping his homebrew PCB down to the mill, [Alessio] simply marks off a few known points, imports the drill file, and lets a computer calculate where to drill the holes. The results are remarkable – with a soldermask and silkscreen equipment, these handmade boards can be just as good as professionally manufactured boards,

There are Windows and OS X binaries for [Alessio]’s tool available on his page, with a video demo available below.

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Current Limiter For A MOT Welder

August 3, 2013 by Mike Szczys 14 Comments

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[Mike Worth] wanted the option to run his Microwave Oven Transformer welding rig at less that full power. After being inspired by some of the other MOT hacks we’ve featured he figured there must be a lot of ways to do this. But his searches on the topic didn’t turn up anything. So he just designed and built his own adjustable current limiter for the welder.

At the beginning of his write-up he details what we would call a bootstrap procedure for the welder. Go back and check out his original build post to see that he had been holding the framework for the cores together using clamps. To make the setup more robust he needed to weld them, but this is the only welder he has access to. So he taped some wood shielding over the coils and fired it up.

The current limiter itself is built from a third MOT. Adjustment is made to the cores by changing out the E and I shaped pieces. This allows for current limiting without altering the windings. [Mike] holds it all in place with a couple of bicycle wheel quick connect skewers.

It just goes to show that you should never get rid of a microwave without pulling the transformer. Even if you don’t need a welder wouldn’t you love a high-voltage bug zapper?

Tools And Talent For Custom Platinum Jewelry

July 30, 2013 by Mike Szczys No comments

The diamond engagement ring is arguably the most universally adopted of all jewelry. It’s artwork that even the most common men and women appreciate, and it’s creation calls for skills that go back centuries. [Jerome Kelty] crafts custom jewelry from platinum. Here’s an in-depth look at his process.

The first step of his Instructable post is so long you might be fooled into thinking it’s the whole post. He shows off the equipment that he used in taking this ring from design to reality — we thought the use of beeswax to pick up small stones is an interesting technique.

Click through the steps to see that he starts with a cad drawing. This model is sent offsite for casting and arrives back as an oversized blank which he then begins to clean up. A range of differend files bring it to its finished shape. He preps the areas where stones will be set. A trip to the buffing wheel gives it the shine it needs before the diamonds are put in place.

Regular Hackaday readers may recognize his name. When [Jerome] isn’t making jewelry he’s building animatronics, like Predator or Stargate replicas.

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PCBs With Powder Coat

July 29, 2013 by Brian Benchoff 48 Comments

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The toner transfer method of PCB production should be a staple in every maker’s bag of tricks. That being said, it’s a far from ideal solution with a lot of things that can go wrong, ruining hours of work. [Ryan] thinks he has a better solution up his sleeve, still using heat activated toner, but replacing the laser printer with a powder coating gun and a laser engraver.

[Ryan] is using a powder coating gun he picked up from Amazon for about $100. The theory behind it is simple: particles of toner coming out of the gun are statically charged, and bonded to the grounded copper clad board. In real powder coat shops, this coating is baked, resulting in a perfectly hard, mirror-like finish. [Ryan] skipped the baking step and instead through the powder coated board into a laser engraver where the PCB design is melted onto the copper. After that, wash the board off, etch it, and Bob’s your uncle.

What’s really interesting about this method of PCB production is that it doesn’t require a very high power laser. [Ryan] was actually having a problem with the toner burning with his laser engraver, so it might be possible to fab PCBs with a high power handheld laser, or even a Blu Ray laser diode.

Propane Forge Built From A Soup Can

July 28, 2013 by Mike Szczys 19 Comments

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It doesn’t look like much, but this easy to build propane forge is just what you need to try your hand at blacksmithing. [Code Cowboy] took on the build after watching this how-to video which shows the fabrication of a small knife after completing the forge build.

The first step is to eat all of the soup (or beans if you prefer). With an empty can in hand the stand — made of two angle brackets — and inlet are attached. Next comes the heat proofing for the walls of the forge. At first glance we thought that cat litter was one of the ingredients, but that’s just an empty container used to haul playground sand. The sand is mixed with equal parts of plaster of paris before adding water to achieve a clay-like consistency. This is packed into the can, with a small opening to receive the metal to be heated.

The torch itself can be used to cure the heat shield. After letting the mixture harden a 30 minute burn will force the rest of the water out of the heat proofing.

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