Day: August 9, 2017

Get Inside A TCXO Clock Chip

August 9, 2017 by 28 Comments

[Pete] wondered how real-time clock modules could be selling on eBay for $1.50 when the main component, the Maxim DS3231 RTC/TCXO chip, cost him more like $4 apiece. Could the cheap modules contain counterfeit chips?

Well, sure they could. But in this case, they didn’t, and [Pete] has the die shots to prove it. He started off by clipping the SOIC leads rather than desoldering — he’s not going to be reusing this chip after he’s cut it in half. Next was a stage of embrittling the case by heating it up with a lighter and dunking it in water. Then he went at it with sandpaper.

It’s cool. You can see the watch crystal inside, and all of the circuitry. The DS3231 includes a TCXO — temperature-corrected crystal oscillator — and it seems to have a bank of capacitors that it connects and disconnects depending on the chip’s temperature to keep the oscillator running at the right speed. [Pete] used one in an offline situation, and it only lost sixteen seconds over a year, so we’d say that they work fine.

If you’d like to know more about how crystals are used to keep time, check out [Jenny]’s excellent article. And if sixteen second per year is way too much for you, tune up your rubidium standard and welcome to the world of the time nuts.

The Sensors Automating Your Commute

August 9, 2017 by 39 Comments

In a bout of frustration I recently realized that the roads have all updated — most people have no idea how — and this sometimes hurts the flow of traffic. This realization happened when an unfortunate person stopped in a left turn lane well before the stop line. The vehicle didn’t trigger the sensor, so cycle after cycle went by and the traffic system never gave the left turn lane a green light, thinking the lane was unoccupied. Had the driver known about this the world would have been a better place. The first step in intelligent automation is sensing, and there are a variety of methods used to sense traffic’s flow.

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Simple hydraulics using syringes

Super Simple Hydraulics Using Syringes

August 9, 2017 by 34 Comments

When making a toy excavator arm, or any robotic arm, the typical approach is to put motors at the joints, or if there isn’t room, to put the motors somewhere else and transfer the force using fishing line and pulleys. [Navin Khambhala] chose instead to do it more like the real excavators, with hydraulics using syringes. And we have to admit, the result it pretty elegant in its simplicity.

The syringes do the job of single-acting hydraulic actuators, one at the motor and the other where the force is needed. In between them, what appears to be clear vinyl tubes carry the fluid between syringes. 12 volt DC motors with bolts on them move nuts attached to the syringe pistons to push and pull the pistons. It is so simple that no further explanation is needed, though like most apparently simple things, we’re sure a lot of effort went into making it that way. The video below shows the finished product, as well as walks through the making of it.

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Laser Cut Enclosures From Eagle Files

August 9, 2017 by 16 Comments

Once a project is finished, it might still need a decent enclosure. While it’s possible to throw a freshly soldered PCB in a standard enclosure, or piece of Tupperware, or cardboard box, these options don’t have the fit and finish of something custom-made. If you have a laser cutter sitting around, it’s a simple matter to cut your own enclosure, but now that process is much easier thanks to [Ray]’s latest project.

Since [Ray] was already using Eagle to design his PCBs, it seemed like a short step to using the Eagle files to design the enclosure as well. The script runs from those files and creates everything necessary to send to the laser cutter for manufacturing. Right now, [Ray] points out that the assembly time for each enclosure can be high, and this method might not be suited for large numbers of enclosures. Additionally, some of the calculations still need to be done by hand, but there are plans to automate everything in the future.

For single projects, though, this script could cut a lot of time off of designing an enclosure and building it from scratch, and could also help improve aesthetics over other options like 3D printed enclosures. Of course, if you have a quality 3D printer around but no laser cutter, there are options for custom enclosures as well.