LiPo Added to LEGO Power Functions Power Brick

LEGO’s Power Functions elements mostly consist of DC motors and the hardware to be driven by those motors like gears and wheels. They also include battery packs, usually a bunch of AA cells in a plastic box. One of the challenges of the system — for hackers, anyway — is interfacing with the product line’s plugs, which resemble 2×2 plates with power and ground connectors built in, designed to be impossible to connect in reverse. It’s difficult to make the physical shape of the plug, with the connectors right where they should be. This hurdle means you also pretty much have to use LEGO’s power boxes or take your chances with frying your components from an unregulated LiPo.

The LiPo Power Brick project serves as a DC-DC power supply, serving up constant 9 V output, with
over current protection limiting current to 3 A peak or 2 A continuous and over-discharge protection shutting down the power supply when it zeroes out. It can be used in conjunction with Sbrick smart Power Functions controllers. The SBrick can also source 3A per channel, which is more than any LEGO PF-compatible power supply can deliver.

The LiPo Power Brick is the same size as a standard 2×4 brick, allowing you to easily add it to your next project.

DPS5005 Makes Digital Power Supply a Snap

Few pieces of gear are more basic to electronics than some kind of power supply. It might be a box of batteries, or it might be a high-end lab supply. [Andreas] took a DPS5005 power supply module that has USB and Bluetooth and used it to build a very capable switching power supply which he then used to build a source measuring unit.

The user interface on the diminutive module is simplistic, so [Andreas] appreciated the PC-based software that can control the supply remotely. The module can output up to 50V, but you should plan accordingly as it does need 1.1 times the maximum voltage output on the input. It will work with lower input voltages, but it just won’t be able to output as high a voltage.

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Give Your Bench Power Supply A Helping Hand

[Sverd Industries] have created a pretty cool bench power supply integrating soldering helping hands into the build. This helps free up some much-needed bench space along with adding that wow factor and having something that looks unique.

The build is made from a custom 3D printed enclosure (Thingiverse files here), however if you have no access to a 3D printer  you could always just re-purpose or roll your own instrument enclosure. Once the enclosure is taken care of, they go on to install the electronics. These are pretty basic, using a laptop PSU with its output attached to the input of a boost/buck module. They did have to change the potentiometers from those small PCB mounted pots to full size ones of the same value though. From there they attach 4 mm banana sockets to the output along with a cheap voltmeter/ammeter LCD module. Another buck converter is attached to the laptop PSU’s output to provide 5 V for a USB socket, along with a power switch for the whole system.

Where this project really shines is the integrated helping hands. These are made from CNC cooling tubes with alligator clips super glued to the end, then heat shrink tubing is placed over the jaws to stop any accidental short circuiting while using them.

This isn’t a life changing hack but it is quite a clever idea if space is a hot commodity where you do your tinkering, plus a DIY bench power supply is almost a rite of passage for the budding hacker.

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Mixed Mode Bench PSU Delivers High Performance

If you have an electronics bench, it follows that you will need some form of bench power supply. While many make do with fixed-voltage supplies it’s safe to say that the most useful bench power supplies have variable voltage and a variable current limiter. These are available in a range of sizes and qualities, and can be had from the usual online suppliers starting with a surprisingly small outlay.

There is however a problem with inexpensive bench power supplies. They are invariably switch-mode designs, and their output will often be noisy. Expensive linear supplies provide a much more noise-free output, but do so at the expense of excessive heat loss when regulating a high voltage drop.

One solution is a mixed-mode design, in which a switch-mode supply does the hard work of reducing the voltage most of the way, and a linear regulator drops the last couple of volts to provide a noise-free output. [Andrei] shows us his design for just such a mixed-mode supply, and it’s one you can have a go at building yourself.

His primary supply is an off-the-shelf switcher that turns mains AC into 24 V DC. This then feeds an LTC1624 buck converter that brings the voltage down to about 1.2 V above the final output voltage, this is in turn fed to a parallel pair of LT3081 linear regulators that deliver the final noise-free output. There is an INA260 for voltage and current measurement, and an Arduino with LCD display as a user interface. His prototype has been nicely constructed using a four-layer PCB, though he suggests it could be made on stripboard with the appropriate SMD adaptors. The cardboard chassis he’s used looks slightly alarming though.

We’ve covered numerous bench power supplies here over the years here at Hackaday. If it is an author’s favourite you are seeking though, take a look at the 723.

USB Charger Fooled into Variable Voltage Source

USB chargers are everywhere and it is the responsibility of every hacker to use this commonly available device to its peak potential. [Septillion] and [Hugatry] have come up with a hack to manipulate a USB charger into becoming a variable voltage source. Their project QC2Control works with chargers that employ Quick Charge 2.0 technology which includes wall warts as well as power banks.

Qualcomm’s Quick Charge is designed to deliver up to 24 watts over a micro USB connector so as to reduce the charging time of compatible devices. It requires both the charger as well as the end device to have compatible power management chips so that they may negotiate voltage limiting cycles.

In their project, [Septillion] and [Hugatry] use a 3.3 V Arduino Pro Mini to talk to the charger in question through a small circuit consisting of a few resistors and diodes. The QC2.0 device outputs voltages of 5 V, 9 V and 12 V when it sees predefined voltage levels transmitted over the D+ and D- lines, set by Arduino and voltage dividers. The code provides function calls to simplify the control of the power supply. The video below shows the hack in action.

Quick Charge has been around for a while and you can dig into the details of the inner workings as well as the design of a compatible power supply from reference designs for the TPS61088 (PDF). The patent (PDF) for the Quick Charge technology has a lot more detail for the curious.

Similar techniques have been used in the past and will prove useful for someone looking for a configurable power supply on the move. This is one for the MacGyver fans.

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Current Sink Keeps The Smoke In

One of the most versatile tools on anyone’s work bench, at least as far as electrical projects are concerned, is a power supply. Often we build our own, but after we’ve cobbled together some banana jacks with a computer’s PSU or dead-bug soldered a LM317 voltage regulator to a wall wart, how will that power supply perform? Since it’s not desirable to use a power supply that’ll let the smoke out of everything it powers (or itself, for that matter) a constant current sink, or load, can help determine the operating limits of the power supply.

[electrobob] built this particular current sink from parts he had lying around. The theory of a constant current sink is relatively straightforward so it’s easily possible to build one from parts out of the junk drawer, provided you can find a few transistors, fuses, an op amp, and some heat sinks. The full set of schematics that [electrobob] designed can be found on his main project page. He’s also gone a step further with this build as well, since he shorted out his first prototype and destroyed some of the transistors. But, using a few extra transistors in his design also improves the safety and performance of the load, so it’s a win-win.

This constant current load also has the added feature of being able to interface with a waveform generator (an Analog Discovery, specifically) and as a result can connect and disconnect the load quickly. If you aren’t in need of an industrial-grade constant current sink and you have some spare parts lying around, this would be a great one to have around the work bench.

A Tiny Bench Power Supply

One of the more popular projects for beginners in electronics is a power supply. Yes, you can always go to Amazon and buy a nice power supply, but unfortunately, we haven’t set up our Amazon affiliate links yet. Instead, we’ll have to go with the next best thing and check out [Tron900]’s mini bench power supply build. It’s extremely capable and cute as a button.

The design goals for this project were to build a small and compact unit using mostly salvaged and recycled components, with all through-hole circuitry. The best guide you’ll ever find for a DIY power supply is one of [Dave Jones]’ earlier video series going over the construction of an adjustable power supply based on an LT3080. [Tron] didn’t have this regulator on hand and wanted to base his design around an op-amp instead. After rummaging through his parts, he found what he was looking for: a TIP3055 power transistor, a neat enclosure that could double as a heatsink and an AD680 voltage reference.

The design of this power supply was simulated in SIMETRIX, and after a few revisions [Tron] had a circuit that worked reasonably well. The circuit was populated on a piece of perfboard, a fantastic front panel was constructed, and one of those ubiquitous volt/ammeter panels added.

This is just a one-off project, but the results are fantastic. This is a very small, very capable power supply that does everything [Tron] needs. It’s accurate enough, at least when measured with a fancy benchtop HP meter, and looks adorable. What more could you want in a benchtop power supply?