Close-Up On The RP2350 HSTX Peripheral

August 20, 2024 by Jenny List 24 Comments

The new Raspberry Pi Pico 2 with its RP2350 microcontroller has only been with us for a short time, and thus its capabilities are still being tested. One of the new peripherals is HSTX, for which the description “High speed serial port” does not adequately describe how far it is from the humble UART which the name might suggest. CNX Software have taken a look at its capabilities, and it’s worth a read.

With a 150 MHz clock and 8 available pins, it’s a serial output with a combined bandwidth of 2400 Mbps, which immediately leaves all manner of potential for streamed outputs. On the RP2040 for example a DVI output was made using the PIO peripherals, while here the example code shows how to use these pins instead. We’re guessing it will be exploited for all manner of pseudo-analogue awesomeness in the manner we’re used to with the I2S peripherals on the EP32. Of course, there’s no corresponding input, but that still leaves plenty of potential.

Have a quick read of our launch coverage of the RP2350, and the Pico 2 board it’s part of.

Custom Pneumatic Cylinders Lock This Monitor Arm In Place

August 9, 2024 by Dan Maloney 8 Comments

Few consumer-grade PCs are what you’d categorize as built to last. Most office-grade machines are as likely as not to give up the ghost after ingesting a few too many dust bunnies, and the average laptop can barely handle a few drops of latte and some muffin crumbs before croaking. Sticking a machine like that in the shop, especially a metal shop, is pretty much a death sentence.

And yet, computers are so useful in the shop that [Lucas] from “Cranktown City” built this neat industrial-strength monitor arm. His design will look familiar to anyone with a swing-arm mic or desk light, although his home-brew parallelogram arm is far sturdier thanks to the weight of the monitor and sheet-metal enclosure it supports. All that weight exceeded the ability of the springs [Lucas] had on hand, which led to the most interesting aspect of the build — a pair of pneumatic locks. These were turned from a scrap of aluminum rod and an old flange-head bolt; when air pressure is applied, the bolt is drawn into the cylinder, which locks the arm in place. To make it easy to unlock the arm, a pneumatic solenoid releases the pressure on the system at the touch of a button. The video below has a full explanation and demonstration.

While we love the idea, there are a few potential problems with the design. The first is that this isn’t a fail-safe design, since pressure is needed to keep the arm locked. That means if the air pressure drops the arm could unlock, letting gravity do a number on your nice monitor. Second is the more serious problem [Lucas] alluded to when he mentioned not wanting to be in the line of fire of those locks should something fail and the piston comes flying out under pressure. That could be fixed with a slight design change to retain the piston in the event of a catastrophic failure.

Problems aside, this was a great build, and we always love [Lucas]’ seat-of-the-pants engineering and his obvious gift for fabrication, of which his wall-mount plasma cutter is a perfect example.

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Adapter Salad: Making Your Own Server Cables Because HP Won’t Sell Them To You

August 8, 2024 by Lewin Day 24 Comments

The world is tough and uncaring sometimes, especially if you’re at home tinkering with HP Enterprise equipment. If you’re in the same boat as [Neel Chauhan], you might have found that HPE is less than interested in interacting with small individual customers. Thus, when a cable was needed, [Neel] was out of luck. The simple solution was to assemble a substitute one instead!

[Neel] had a HPE ProLiant ML110 Gen11 server, which was to be used as network-attached storage (NAS). Unfortunately, it was bought as an open box, and lacked an appropriate serial-attached SCSI (SAS) cable. Sadly, HPE support was of no assistance in sourcing one.

SlimSAS LP x8 to dual MiniSAS x4 cables aren’t easy to find from anyone else, it turns out. Thus, [Neel] turned to Amazon for help sourcing a combination of parts to make this work. A SlimSAS LP 8X to 2x MiniSAS SFF-8643 cable was used, along with a pair of Mini SAS SFF-8087 to SAS HD SFF-8643 female adapters. From there, SFF-8087 cables could be used to hook up to the actual SAS devices required. The total cost? $102.15.

The stack of cables and adapters looks a bit silly, but it works—and it got [Neel]’s NAS up and running. It’s frustrating when you have to go to such lengths, but it’s not the first time we’ve seen hackers have to recreate obscure cables or connectors from scratch! What’s the craziest adapter salad you’ve ever made?

The 555 As A MOSFET Driver

August 5, 2024 by Jenny List 25 Comments

To drive a MOSFET requires more than merely a logic level output, there’s a requirement to charge the device’s gate which necessitates a suitable buffer amplifier. A variety of different approaches can be taken, from a bunch of logic buffers in parallel to a specialised MOSFET driver, but [Mr. T’s Design Graveyard] is here with a surprising alternative. As it turns out, the ever-useful 555 timer chip does the job admirably.

It’s a simple enough circuit, the threshold pin is pulled high so the output goes high, and the PWM drive from an Arduino is hooked up to the reset pin. A bipolar 555 can dump a surprising amount of current, so it’s perfectly happy with a MOSFET. We’re warned that the CMOS variants don’t have this current feature, and he admits that the 555 takes a bit of current itself, but if you have the need and a 555 is in your parts bin, why not!

This will of course come as little surprise to anyone who played with robots back in the day, as a 555 or particularly the 556 dual version made a pretty good and very cheap driver for small motors. If you’ve ever wondered how these classic hips work, we recently featured an in-depth look.

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Print Your Own Magnetic Connector

July 27, 2024 by Al Williams 22 Comments

If you have a late-model laptop, you’ve probably seen how the chargers magnetically snap into place. In theory, this should be easy to recreate for your own purposes. But why reinvent the wheel when [DarthKaker] has already done the work for you — assuming you only need two conductors.

The 3D-printed shells take the usual round magnets. Obviously, the north pole on one part should point to the south pole on the other part. In addition, if polarity matters, you should also have each housing contain one north-facing and one south-facing magnet so that the connectors will only mate one way.

It appears the project uses wires soldered or spot welded to the magnets. Heating magnets sometimes has bad effects, so we might try something different. For example, you could solder the wires to thin washers affixed to the magnets with epoxy, perhaps. Or use the magnets for alignment and make a different arrangement for the contacts, although that would take a different shell design.

We have talked about magnet soldering for connectors before. Don’t forget that you can build magnets into your prints, too.

A Simple Liquid Level Indicator With A Single IC

July 25, 2024 by Lewin Day 14 Comments

Often, the only liquid level indicator you need is your eyes, such as when looking at your cold beverage on a summer’s day. Other times, though, it’s useful to have some kind of indicator light that can tell you the same. [Hulk] shows us how to build one for a water tank using a single IC and some cheap supporting components.

If you’re unfamiliar with the ULN2003, it’s a simple Darlington transistor array with seven transistors inside. It can thus be used to switch seven LEDs without a lot of trouble. In this case, green, yellow, and red LEDs were hooked up to the outputs of the transistors in the ULN2003. Meanwhile, the base of each transistor is connected to an electrode placed at a different height in the water tank. A further positive electrode is placed in the tank connected to 12 volts. As the water raises to the height of each electrode, current flow from the base to the positive electrode switches the corresponding transistor on, and the LED in turn. Thus, you have a useful liquid level indicator with seven distinct output levels.

It’s a neat build that might prove useful if you need to check levels in a big opaque tank at a glance. Just note that it might need some maintenance over time, as the electrodes are unlikely to remain completely corrosion free if left in water. We’ve seen some other great uses of the ULN2003 before, too. Video after the break.

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Exploring Cheap Tantalum Caps Of Mysterious Provenance

July 22, 2024 by Dan Maloney 25 Comments

We’ve all heard about the perils of counterfeit chips, and more than a few of us have probably been bitten by those scruple-free types who run random chips through a laser marker and foist them off as something they’re not. Honestly, we’ve never understood the business model here — it seems like the counterfeiters spend almost as much time and effort faking chips as they would just getting the real ones. But we digress.

Unfortunately, integrated circuits aren’t the only parts that can be profitably faked, as [Amateur Hardware Repair] shows us with this look at questionable tantalum capacitors. In the market for some tantalums for a repair project, the offerings at AliExpress proved too tempting to resist, despite being advertised alongside 1,000 gram gold bars for $121 each. Wisely, he also ordered samples from more reputable dealers like LCSC, DigiKey, and Mouser, although not at the same improbably low unit price.

It was pretty much clear where this would be going just from the shipping. While the parts houses all shipped their tantalums in Mylar bags with humidity indicators, with all but LCSC including a desiccant pack, the AliExpress package came carefully enrobed in — plastic cling wrap? The Ali tantalums were also physically different from the other parts: they were considerably smaller, the leads seemed a little chowdered up, and the package markings were quite messy and somewhat illegible. But the proof is in the testing, and while all the more expensive parts tested fine in terms of capacitance and equivalent series resistance, the caps of unknown provenance had ESRs in the 30 milliohm range, three to five times what the reputable caps measured.

None of this is to say that there aren’t some screaming deals on marketplaces like AliExpress, Amazon, and eBay, of course. It’s not even necessarily proof that these parts were in fact counterfeit, it could be that they were just surplus parts that hadn’t been stored under controlled conditions. But you get what you pay for, and as noted in the comments below the video, a lot of what you’re paying for at the parts houses is lot tracebility.

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