A DIY Sprinkler Controller Using An ESP8266

There is something strangely amusing about the idea of a sprinkler system relying on a cloud. But it was this limitation in some commercial offerings that led [Zack Lalanne] to create his own controller when it was time to upgrade his aging irrigator.

It’s a straightforward enough device, he’s taken an ESP8266 on the ubiquitous NodeMCU board, and added a shift register for some output line expansion to drive a set of relays. The interest here lies with the software, in which he’s used the ESPHome firmware and added his own custom part for the shift register. This change alone should be useful for many other experimenters with the ‘8266 and ESPHome combination.

The ESP8266 end of the device ties in with his instance of the Home Assistant home automation hub software. On this he’s been able to tie in all his various sprinkler outputs he added, and apply whatever automation scripts he chooses. The result is a freshly watered lawn, with not a cloud in the sky (or backend).

The value of this project lies only partly in its use for sprinkler owners, for us it also lies in the clear write-up showing the way for others with similar home automation tasks. It’s not the only way to make an ESP sprinkler controller, you should also see this one from 2017.

A Trash-Steam-Machine-80

Sometimes for a retrocomputing enthusiast it can be challenging to see a surviving machine gutted and used for another purpose. But in the case of [Tom Pick]’s Radio Shack TRS-80 based Steam Machine PC we can forgive him, because it began with a very unpromising machine that had most definitely seen better days.

The TRS-80 in question is a Model III, the all-in-one console device with a numerical keypad, CRT monitor, and dual 5.25″ floppy drives built in. This provided plenty of space for the components of a modern PC with a 12″ LCD monitor. The PC itself is a run-of-the mill 2.6 GHz Pentium and nothing exceptional, but its input devices are of note. The keyboard is a Red Dragon mechanical item which has been made to look the part in place of the old Radio Shack item with a set of custom colour-coded keycaps, while the pointing device in a particularly neat touch is a modern Radio Shack-branded mouse. The boot screen is the proper Radio Shack logo from the TRS-80’s heyday, meaning that if you didn’t know any differently you might think this was meant to be. Sadly the two floppy drives are unconnected, though we’re sure it would be possible to make a modern PC see them for a bit of 360k storage goodness.

We don’t see as many projects featuring the TRS-80 series as we should, and the model III is a particular rarity. Far more common in these pages is the portable Model 100, most recently gaining a cellular connection.

Plot Your Way Past A Tiny Buffer

There is a dedicated community of plotter enthusiasts who keep their often-aging X-Y axis pen drawing devices going decades after they were built, and who share plotter-generated paper artwork online. [Dhananjay Balan] was seduced by this, so acquired a second-hand HP7440A through eBay and set about bringing it to life.

Bringing it to life was in the first instance the usual progression of cleaning the mechanism and checking all was in order, before doing a bit of research to find that the missing power supply was a 10-0-10V AC item. Then some adapters and a USB-to-serial port had it talking to a modern PC, and thanks to the wonders of HPGL it was working once more. This could thus have been a very simple tale worthy of the dreaded Not A Hack moniker, had the focus then not changed from the hardware into the software.

Back in the day, a 60-byte buffer in a plotter must have seemed huge. But in 2019 a plotter can be sent data at a rate that will swiftly fill it, after which the commands are not stored and are never drawn. Introducing a delay between sending commands solves the problem, but at the expense of very slow plotting. This was solved with a very clever use of the HPGL command to send the pen position, which waits until the pen has finished moving before sending its return value. This became a handy way to detect when the plotter was ready for more, allowing speedier printing without buffer overruns.

The plotter has an expansion port into which an optional module containing trigonometric drawing functions could have been plugged, but was missing in this example. HP’s idea was that the buffer was so small that a programmer would have difficulty writing their own, but the buffer hack in the previous paragraph put paid to that. Python code for all this and more is in a handy GitHub repository.

Via Hacker News.

Here’s How Hard It Is To Produce A Conference Badge

Making an event badge is hard work. Making a single prototype badge is hard enough, but the whole process of sourcing components and coordinating manufacture for hundreds of badges on a shoestring budget with the looming deadline of the event and its expectant attendees is a Herculean task.

[Uri Shaked] is one who bears the scars of producing an event badge, and he’s written a fascinating account of his experience. The conference in question was Aramcon 2019, a private tech event in Israel, and the badge has an nRF52840 driving an e-ink display, multi-colour LED, and an audio codec, with a set of full-size keyboard keys as user input. Since the nRF chip supports mesh networking, the idea was to produce a badge capable of streaming audio across the entire event.

A clothes-pin as a programming jig, we like it!
A clothes-pin as a programming jig, we like it!

We follow the team through nail-biting months of prototype boards, reversed connectors with last-minute cable bodges, compatible parts that didn’t turn out to be quite so compatible, and wrong footprints, and see them arriving at a badge which worked, but without the audio they’d hoped for. Along the way they came up with a clothes-pin-based programming jig which would surely have merited its own Hackaday write-up had they covered it on its own. Demonstrating the mesh networking by turning a whole auditorium’s worth of badges LEDs yellow was their reward, and we can see they’ve produced a very creditable badge. We particularly like the use of keyboard key switches, and we commend them for planning a life for the badge after the event.

Our Hackaday colleague [Brian Benchoff] is a veteran of badge production, read his write-ups of the genesis of our Superconference 2017 badge and the Tindie dog badge. Meanwhile the keen-eyed among you may recognise the nRF52840 as the guts of the latest generation of Particle boards.

This is the Raspberry Pi Mini Laptop that We Want

In the seven years since the Raspberry Pi was first launched to an expectant audience we have seen many laptops featuring the fruit-themed single board computers. Some of them have been pretty jaw-dropping in their quality, so for a new one to make us stop and gape it needs to be something really special. On cue, here comes [Igor Brkić] with one of the neatest efforts we’ve seen, a high quality Pi laptop that’s smaller in frontal area than many smartphones.

At its heart is a Pimoroni Hyperpixel touchscreen HAT, and a Pi sitting behind it that has been stripped of all bulky connectors to reduce its height. The keyboard is a mini Bluetooth affair, and power comes courtesy of a deconstructed USB power bank with a lithium-ion pouch cell. The whole is contained within a neatly designed 3D-printed clamshell enclosure, making for a tiny and very neat laptop. We want one, and now you probably do too. (We wouldn’t say “no” to some level shifters and a GPIO port…)

If we had to pick another high-quality Pi laptop to compare this one with, it would have to be this one with a Psion-inspired hinge.

In This Aussie’s Back Yard, No Cat Is Safe From An Automated Soaking!

Some of us here at Hackaday are cat lovers, but we also understand that a plethora of unwanted cats using a suburban back garden can be bothersome, and a few years ago we featured a project from Aussie YouTuber [Craig Turner], in which he created a motion-detecting water spray for use as a relatively harmless cat repellent. Now he’s back with an updated version which is a little slicker and easier to make.

At its heart is the same PIR-turns-on-water operation, but this time there is a solenoid valve and purpose-built nozzle instead of a car central locking actuator and a lawn sprayer. Doing the electronic work is an off-the-shelf PIR module, so there is no  longer any need to hack a security PIR detector. Add in some pipe sections and PTFE tape with a bit of hot glue, and the result is a far more professional and streamlined device. The video gives a full run-down on construction, though we notice he neglected to emphasise the polarity of his protection diode so keep an eye out if you follow his example.

So if the thought of a continuous supply of free feline company courtesy of your neighbours is not for you then now you are equipped to send them packing. The latest video incarnation of the project is below the break, but if you are in search of the original then you can go back to our coverage at the time.

Continue reading “In This Aussie’s Back Yard, No Cat Is Safe From An Automated Soaking!”

Battle Tested Current Limiter for Cheap DC Motor Controllers

Running a brushed motor in muddy or dusty environments takes a toll on controllers, with both heavy back EMF and high stall currents. This explains one of the challenge in Europe’s Hacky Racer series, which is decidedly more off-road than America’s Power Racing Series.

In pushing these little electric vehicles to the limits, many builders use brushless Chinese scooter motors since they’re both available and inexpensive. Others take the brushed DC route if they’re lucky enough to score a motor — and then the challenge becomes getting the most performance without burning up your controller. To fix this, [MechanicalCat] has come up with a current limiter for cheap DC motor controllers.

Circuit protection added to motor controller

The full write-up is in the included PDF file, and describes the set-up of an Arduino Nano sitting between throttle and controller, and taking feedback from a current sensor. The controller in question is a 4QD Porter 10 so an extra component is a DC-to-DC converter to provide a floating ground for the Arduino. However, there is also the intriguing possibility of the same set-up being used with absurdly cheap Chinese motor controllers. There is also advice on fitting flyback diodes, something which might have saved one controller in the Hackaday pits last year.

It’s yet to be seen what effect this will have on Hacky Racer competitiveness, however its applications go far beyond that field into anywhere a reliable small DC motor drive on the cheap is required. Meanwhile, if you’re unsure where this Hacky Racer stuff came from, you could start here.