Quick and Dirty Driver Tips for Surplus VFDs

Sometimes it seems like eBay is the world’s junk bin, and we mean that in the best possible way. The variety of parts available for a pittance boggles the mind sometimes, especially when the parts were once ordered in massive quantities but have since gone obsolete. The urge to order parts like these in bulk can be overwhelming, and sooner or later, you’ll find yourself with a fistful of old stuff but no idea how to put it to use.

Case in point: the box of Russian surplus seven-segment vacuum fluorescent displays (VFDs) that [w_k_fay] had to figure out how to use. The result is a tutorial on quick and dirty VFD drivers that looks pretty handy. [w_k_fay] takes pains to point out that these are practical tips for putting surplus VFDs to work, as opposed to engineered solutions. He starts with tips on characterizing your surplus tubes in case you don’t have a pinout. A 1.5 V battery will suffice for the hot cathode, while a 9 V battery will turn on the segments. The VFDs can be treated much like a common cathode LED display, and a simple circuit driving the tube with a 4026 decade counter can be seen below. He also covers the challenges of driving VFDs from microcontrollers, and promises a full build of a frequency counter wherein the mysteries of multiplexing will be addressed.

Sounds like it’s time to stock up on those surplus VFDs and put them to work. For inspiration, take a look at this minimalist VFD clock, or perhaps mix VFDs with Nixies to satisfy your urge for all things glowy.

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Celebrate Display Diversity for a Circuit Circus Clock

There’s a lot to be said for nice, tidy projects where everything lines up and looks pretty. Seeing straight lines and pleasing proportions speaks to our obsessive-compulsive tendencies, and tends to soothe the mind and calm the spirit. But disorder is not without its charm, and mixing it up a little from time to time, such as with this mixed-media digital clock, can be a good idea.

Now, we know what you’re thinking — yet another Nixie clock. True, but that’s only half the story — or more accurately, one-sixth. There’s but a single Nixie in [Fuselage]’s circus-punk themed clock, used for the least significant digit in the hours part of the display. The other digits are displayed with four seven-segment devices — a Numitron, a vacuum fluorescent display, and an LED dot display — plus a real oddball, an old electromechanical display with individual slides for each character and a rear-screen projector. The RTC part of the project is standard Arduino fare, but as you can imagine the power supply needed for such a diversity of displays is pretty complex and has to provide everything from +5 to -270 volts. Each display needs its own driver, too, making this more of a zoo than a circus. The mixed up look just works with the circus theme, too. We’d really like more information on the projector display, though.

Looking for a real statement for your next clock build? Check out the rare as hens’ teeth NIMO tube.

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VFD Puts the Suck Back into Desoldering Station

A dedicated desoldering station is a fantastic tool if you’re in the business of harvesting components from old gear. Having heat and suction in a single tool is far more convenient than futzing with spring-loaded solder suckers or braid, but only as long as the suction in the desoldering tool has a little oomph behind it. So if the suction on your solder sucker is starting to suck, this simple VFD can help restore performance.

Luckily for [Mr. Carlson], his Hakko 470 desoldering station is equipped with an AC induction motor, so it’s a perfect candidate for a variable frequency drive to boost performance. He decided to build a simple VFD that boosts the frequency from 60-Hz mains to about 90-Hz, thereby jacking the motor speed up by 50%. The VFD is just a TL494 PWM chip gating the primary coil of a power transformer through a MOSFET. Duty cycle and frequency are set by trimmers, and the whole thing is housed in an old chassis attached to the Hakko via an anachronistic socket and plug from the vacuum tube days. That’s a nice touch, though, because the Hakko can be returned to stock operation by a simple bridging plug, and the video below shows the marked difference in motor speed both with and without the VFD plugged in.

We’ve marveled at [Mr. Carlson]’s instrument packed lab before and watched his insider’s tour of a vintage radio transmitter. Here’s hoping we get to see more of his hopped-up solder sucker in action soon.

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Reusing Motors From Washing Machines

Big ol’ motors are great when you need to get a big job done, but they can be expensive or hard to source new. However, there’s a source of big, fat, juicy motors right at home for most people – the garden variety washing machine. These motors would usually require a special controller, however [Jerry] is here to show us how to hack the controller that comes with the machine.

The hack begins as [Jerry] decides to gut a Maytag MAH7500 Neptune front loader. Many projects exist that borrow the motor but rely on a seperately sourced variable frequency drive, so the goal was to see if the machine’s original controller was usable. The machine was first troubleshooted using a factory service mode, which spins the drum at a set speed if everything is working correctly.

From there, it was a relatively simple job to source the machine schematics to identify the pinouts of the various connectors.  After some experimentation with a scope and a function generator, [Jerry] was able to get the motor spinning with the original controller doing the hard work.

It’s a simple hack, and one that relies on the availability of documentation to get the job done, but it’s a great inspiration for anyone else looking to drive similar motors in their own projects. The benefit is that by using the original motor controller, you can be confident that it’s properly rated for the motor on hand.

Perhaps instead of an induction motor, you’d rather drive a high powered brushless DC motor? This project can help.

Fighting Machine Tool Chatter with a 555 Timer

Vibration is a fact of life in almost every machining operation. Whether you’re milling, drilling, turning, or grinding, vibration can result in chatter that can ruin a part. Fighting chatter has generally been a matter of adding more mass to the machine, but if you’re clever about things, chatter reduction can be accomplished electronically, too. (YouTube, embedded below.)

When you know a little something about resonance, machine vibration and chatter start to make sense. [AvE] spends quite a bit of time explaining and demonstrating resonance in the video — fair warning about his usual salty shop language. His goal with the demo is to show that chatter comes from continued excitation of a flexible beam, which in this case is a piece of stock in the lathe chuck with no tailstock support. The idea is that by rapidly varying the speed of the lathe slightly, the system never spends very long at the resonant frequency. His method relies on a variable-frequency drive (VFD) with programmable IO pins. A simple 555 timer board drives a relay to toggle the IO pins on and off, cycling the VFD up and down by a couple of hertz. The resulting 100 RPM change in spindle speed as the timer cycles reduces the amount of time spent at the resonant frequency. The results don’t look too bad — not perfect, but a definite improvement.

It’s an interesting technique to keep in mind, and a big step up from the usual technique of more mass.

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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.

CNC Machine Boasts Big Bed, Impressive Power from Off-the-Shelf Parts

A lot of homebrew CNC machines end up being glorified plotters with a router attached that are good for little more than milling soft materials like wood and plastic. So if you have a burning need to mill harder materials like aluminum and mild steel quickly and quietly, set your sights higher and build a large bed CNC machine with off-the-shelf components.

With a budget of 2000 €, [SörenS7] was not as constrained as a lot of the lower end CNC builds we’ve seen, which almost always rely on 3D-printed parts or even materials sourced from the trash can. And while we certainly applaud every CNC build, this one shows that affordable and easily sourced mechatronics can result in a bolt-up build of considerable capability. [SörenS7]’s BOM for this machine is 100% catalog shopping, from the aluminum extrusion bed and gantry to the linear bearings and recirculating-ball lead screws. The working area is a generous 900 x 400 x 120mm, the steppers are beefy NEMA23s, and the spindle is a 3-kW VFD unit for plenty of power. The video below shows the machine’s impressive performance dry cutting aluminum.

All told, [SörenS7] came in 500 € under budget, which is a tempting price point for a machine this big and capable.

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