LEDs Give HP 3457A DDM’s LCD Display the Boot

Have you ever been so frustrated with a digital display that you wanted to rip the whole thing out and create a better one? That is exactly what [xi] did. Replacing their constantly used HP 3457A multimeter’s LCD display with a brighter LED one was a necessary project — and a stress reducing one at that.

While this digital multimeter is well-known for its reliability, its standard display is rather lacking. In fact, there are several mods already out there that simply add a backlight. However, as [xi] notes, LCD screens always have a certain angle where they still don’t quite show properly. So this hack reverses the LCD’s protocol and details the process of creating new LED display.

The issue of dim displays that comes with traditional digital multimeters is not a new one. One solution to this that we have seen before is a hack where someone decided to add a backlight onto their cheap multimeter. [Ken Kaarvik] got around the dimness altogether by giving his multimeter a wireless remote display of his choosing. It is interesting to see the different solutions that are made to the same nuisance. The first item on the agenda of [xi]’s hack was to successfully analyze the HP LCD protocol. With the aid of an ATmega32, the digits were decoded throughout the transmission frames.

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How Many Hacks in an LED Display?

There are so many nice hacks in [Joekutz]’s retro LED display project that it’s hard to know where to start. There’s his DIY LED display controlled by an Arduino UNO. To have some text or picture for the display, he’s wired the output of a Bluetooth speaker directly to the Arduino, and sends it speaker tones that encode the text to draw. And as if that wasn’t enough, he’s hacked a quartz driver board from an analog clock to use the display as a clock as well.

Let’s start with the LED matrix display, perhaps the best excuse for trying your hand at shift registers. This display uses two such 8-bit shift registers daisy chained together feeding two 8-bit Darlington arrays. The display has ten rows of sixteen columns, and you guessed it, the columns are controlled by the sixteen shift registers. Two Arduino pins tell the shift registers which column to turn on. The rows are turned on and off using ten transistors controlled by ten more Arduino pins. Scanning at 80 frames per second he gets a nice, flickerless display.

To make both the LED matrix circuit board and the control board, [Joekutz] carved out isolation paths in copper clad boards using his homemade CNC mill. Be sure to check out the first video below to see his misadventures with it that ultimately led to his gorgeous boards.

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Hackaday Links: May 21, 2017

It’s time to talk about something of supreme importance to all Hackaday readers. The first trailer for the new Star Trek series is out. Some initial thoughts: the production values are through the roof, and some of this was filmed in Jordan (thank the king for that). The writers have thrown in some obvious references to classic Trek in this trailer (taking a spacesuit into a gigantic alien thing a la TMP). There are a few new species, even though this is set about 10 years before waaaait a second, those are the Klingons?

In other news, [Seth MacFarlane] is doing a thing that looks like a Galaxy Quest series. We can only hope it’s half as good as a Galaxy Quest series could be.

The Dayton Hamvention should have been this week, but it’s never going to happen again. The Hara Arena, the traditional venue for the biggest amateur radio meet on the continent (thankfully) closed this year. Last year it was looking old and tired. This year, Hamvention moved to Xenia, Ohio, and it looks like we’re still getting the best ham swap meet on the planet. Remember: if you  drove out to Hamvention, the Air Force museum is well worth the visit. This year they have the fourth hangar open, full of space craft goodness.

Last week we saw an Open Source firmware for hoverboards, electric unicycles, and other explodey bits of self-balancing transportation. [Casainho], the brains behind this outfit, recently received an eBike controller from China. As you would expect, it’s based on the same hardware as these hoverboards and unicycles. That means there’s now Open Source firmware for eBikes.

Last year, [Cisco] built a cute little walking robot. Now it’s up on Kickstarter.

This week saw the announcement of the Monoprice Mini Delta, the much-anticipated 3D printer that will sell for less than $200. For one reason or another, I was cruising eBay this week and came upon this. They say yesterday’s trash is tomorrow’s collectors’ item, you know…

A new Tek scope will be announced in the coming weeks. What are the cool bits? It has a big touchscreen. That’s about all we know.

The ESP32 is the next great wonderchip, and has been for a while now. The ESP32 also has a CAN peripheral stuffed in there somewhere, and that means WiFi and Bluetooth-enabled cars. [Thomas] has been working on getting a driver up and running. There’s a thread on the ESP32 forum, a Hackaday.io page, and a GitHub page.

What do you do when you have a nice old Vacuum Fluorescent Display and want to show some stats from your computer? You build a thing that looks like it’s taken from a cash register. This is a project from [Micah Scott], and it has everything: electronics 3D modeling, magnets, print smoothing, creating snap-fit parts, and beautiful old displays.

Here’s something that randomly showed up in our Tip Line. [Mark] recently found some unused HP 5082-7000 segment displays in a collection of electronic components (pics below). According to some relevant literature, these were the first LED display package available, ever.  They were released in 1969, they’re BCD, and were obviously very expensive. [Mark] is wondering how many of these were actually produced, and we’re all interested in the actual value of these things. If anyone knows if these are just prototypes, or if they went into production (and what they were used for), leave a note in the comments.

Handheld Sudoku (Assuming You Have Large Hands)

[Hari Waguna] wanted to build a computerized Sudoku game. Ordinarily, that wouldn’t be a big deal. You can buy one, of course, but what fun is that? There’s plenty of apps for phones, but again, not much of a challenge. If you want to preserve your hacker cred, you’d use a CPU board like an Arduino or a Raspberry Pi with an LCD screen, right? But if you want to grow your hacker cred, you’d follow [Hari’s] lead and use 81 seven-segment displays and a membrane keyboard.

Driving that many displays takes some doing (in this case shift registers). [Hari] uses some other tricks, like reading the keyboard using a single pin (and a resistor network). He’s made several videos about the project, including the one below.

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64×16 LED MQTT Laundry Display

When you have an MQTT broker receiving messages, you want to be able to see them. [Xose Pérez] already had a system set up that sent him notifications, but he had a pair of 32×16 LED matrices, so he decided to make a big, bright sign to let him know when he got an important message sent to the broker.

[Xose Pérez] had already built a laundry monitor which was sending messages to an MQTT broker so he wouldn’t forget his laundry sitting in the washing machine. To communicate with the broker, he used an ESP-12. He had already ported an Arduino library for the Holtek HT1362C display drivers used by the matrices to work with his driver board.

mqtt-led-matrix-driver-boardHe wanted to try out SMD soldering so he built a custom PCB to hold the ESP-12, power supply, passive components, and a connector and he describes his methods and results. Instead of hardcoded messages, he wanted the system to be configurable and display messages coming in, not only from his laundry system, but also from other sensors. A web interface, built with jQuery and WebSockets, running on the ESP-12 allows the user to subscribe to a topic on the broker and show a customized name and value on the display when a payload is available.

All-in-all, [Xose Pérez] has posted a great tutorial in which he goes over the hardware he built, the libraries he used, SMD soldering, how he made the enclosure, and even his choice in IDE (PlatformIO). He also posted the software, board designs and enclosure models software and hardware on bitbucket. The end result is a great looking LED matrix that displays not only his laundry’s status, but also anything else he wants to from his MQTT broker.

If you want to try your hand with MQTT, the ESP8266 is a wonderful device for sensor nodes, and any Linux box (like the Raspberry Pi) makes an easy broker. Check out [Elliot Williams’] Minimal MQTT series and you will be up and running in no time.

SIM Card Connectors and White PCBs Make Huge LED Snowflakes Happen

[Mike Harrison] talked about designing and building a huge scale LED lighting installation in which PCBs were used as both electrical and mechanical elements, and presented at Electromagnetic Field 2016. The project involved 84,000 RGBW LEDs, 14,000 microcontrollers and 25,000 PCBs. It had some different problems to solve compared to small jobs, but [Mike] shared techniques that could be equally applied to smaller scale projects or applications. He goes into detail on designing for manufacture and assembly, sourcing the parts, and building the units on-site.

The installation itself was a snowflake display for a high-end shopping mall in Hong Kong in the 2015 Christmas season. [Mike] wanted a small number of modular boards that could be connected together on-site to make up the right shapes. In an effort to minimize the kinds of manufacturing and parts needed, he ended up using modular white PCBs as structural elements as well as electrical. With the exception of some minor hardware like steel wire supports, no part of the huge snowflakes required anything outside of usual PCB manufacturing processes to make. The fewer suppliers, the fewer potential problems. [Mike] goes into design detail at 6:28 in the video.

For the connections between the boards, he ended up using SIM card connectors intended for cell phones. Some testing led to choosing a connector that matched up well with the thickness of a 1.6mm PCB used as a spacer. About 28,000 of them were used, and for a while in 2015 it was very hard to get a hold of that particular part, because they had cleaned everyone out! Continue reading “SIM Card Connectors and White PCBs Make Huge LED Snowflakes Happen”

How Many LEDs are Too Many?

“Should you answer a rhetorical question?” But anyway, the answer is that you can never have enough LEDs. At least that’s what [Adam Haile] at maniacallabs seems to think. So far, he’s up to 3,072.

We’ve reported on a previous big-LED build of [Adam]’s before, called the “Colossus”. And while this current display is physically smaller, it’s got a lot more LEDs. And that means a lot more, well, everything else. Weighing in at roughly 500W when full-on, with 175-part 3D printed frame and diffuser elements and driven by three Teensy 3.2 microcontrollers driving shift registers, this display is capable of putting out 60 frames per second of blinding RGB LED goodness.

The designs, adapter boards, and animation code will be posted once they’ve “had a chance to clean things up a little”. Here’s hoping that’s soon! [Edit: Code and designs are here. Thanks Adam!]

If you’re in the greater Washington DC area, you can even swing by the NoVA Maker Faire in Reston to check it out in person. If you do, tell ’em Hackaday sent you.

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