Thrift Store Razor Scooter Gets More Kick

Beyond pride, the biggest issue keeping adults off small motorized scooters is the fact that their tiny motors usually don’t have the power to move anything heavier than your average eighth grader. That didn’t stop [The_Didlyest] from snapping up this $7 thrift store find, but it did mean the hot pink scooter would need to be beefed up if it had any hope of moving 170 lbs of hacker.

Logically, the first step was fitting a more capable motor. [The_Didlyest] used an electric wheelchair motor which had a similar enough diameter that mounting it was fairly straightforward. The original sprocket and chain are still used, as are the mounting holes in the frame (though they had to be tapped to a larger size). That said, the new motor is considerably longer than its predecessor so some frame metal had to be cut away. This left the scooter without a kickstand and with a few inches of motor hanging out of its left side, but it’s all in the name of progress.

Naturally the upgraded motor needed similarly upgraded batteries to power it, so [The_Didlyest] put together a custom pack using eighteen 18650 cells spot welded together for a total output of 25V. Coupled with a 60A battery management system (BMS), the final 6S 3P configured pack is a very professional little unit, though the liberal application of duct tape keeps it from getting too full of itself.

Unfortunately the original motor controller consisted of nothing but relays, and didn’t allow adjusting speed. So that needed to go as well. In its place is a homebrew speed controller made with three parallel MOSFETs and an Arduino to read the analog value from the throttle and convert that into a PWM signal.

[The_Didlyest] says the rear tire is now in need of an upgrade to transmit all this new power to the road, and some gearing might be in order, but otherwise the scooter rebuild was a complete success. Capable of mastering hills and with a top speed of about 10 MPH, the performance is certainly better than the stock hardware.

Of course this is far from the first time we’ve seen somebody put a little extra pepper on a scooter. Some of them even end up being street-legal rides.

The Crustacean Battle Bot of your Nightmares

We’ve all seen a movie or TV show that got our imagination going, and the more studious of us might get fired up over a good book (one without pictures, even). You never know were inspiration might come from, which is why it’s so hard to track down in the first place. But one place we don’t often hear about providing many hackers with project ideas is the grocery store. But of course the more we learn about [Michael Kohn], the more we realize he’s got a very unique vision.

On a recent trip to the grocery store, [Michael] saw a two pack of frozen lobsters and thought they would make fine battling robots. You know, as one does. Unfortunately the process of taking a frozen lobster and turning it into a combat droid (which incidentally does include eating the thing at some point in the timeline) ended up being so disgusting that he only finished one of them. Whether that makes this poor fellow the winner or loser though…that’s a question that will require some contemplation.

The first step was cooking and eating the beast, and after that came cleaning the shell of as much remaining meat and innards as possible. He then baked it in a toaster oven for 40 minutes and let it sit for a couple of days to make sure it didn’t have any residual smell. Once he confirmed the shell was clean, he glued it back together and got started on mounting it to his hardware.

A wooden frame under the lobster holds the dual HD-1711MG mini servos that power the karate chop action of the claws, as well as the electronics. [Michael] used a ATtiny85 and NTD4963N MOSFETs to make a basic RC platform which responds to IR from a Syma S107 toy helicopter controller. He tried to power everything with AAA and then AA batteries, but found they just didn’t give him the juice he needed once the bot got going. So the final version utilizes a 5 V regulator and a standard RC 7.2v LiPO battery pack.

If you’re not big on shellfish, never fear. He’s created similar roving contraptions based around sausages and carrots too. One could say he’s truly a man of refined…taste.

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LED “Candle” Gets the 555 Treatment

Regular readers may recall we recently covered a neat Arduino trick that allowed you to “blow out” an LED as if it was a candle. The idea was that the LED itself could be used as a rudimentary temperature sensor, and the Arduino code would turn the LED on and off when a change was detected in its forward voltage drop. You need to oversample the Arduino’s ADC to detect the few millivolt change reliably, but overall it’s pretty simple once you understand the principle.

But [Andrzej Laczewski], like many of our beloved readers, feels the Arduino and other microcontrollers can be a crutch if used exclusively. So he set out to replicate this hack with that most cherished of ICs, the 555 timer. In the video after the break, he demonstrates his “old-school” LED candle for anyone who thinks the only way to control an LED is with digitalWrite.

Not to say it’s easy to replicate the original Arduino project with a 555, or that it’s even practical. [Andrzej] simply wanted to show it was possible, which is something we always respect around these parts. He goes into great detail on how he developed and tested the circuit, even including oscilloscope screenshots showing how the different components work together in real-time. But the short version is that a MOSFET is used to turn the LED on and off, a comparator detects change in the LED’s voltage drop, and the 555 is used to control how long the LED stays off for.

Ever the traditionalist, [Andrzej] wrapped up this build by etching his own PCB using a variation of the classic laser toner transfer method. If this all looks a bit too much like Black Magic to you, there’s no shame in sticking with the Arduino version. At 1/20th of the parts count, and with no calibration required, who’s to say which version is “simpler”.

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Transistor Fundamentals Animated

When we were in school, every description of how transistors work was pretty dry and had a lot of math involved. We suppose you might have had a great instructor who was able to explain things more intuitively, but that was luck of the draw and statistically unlikely. These days, there are so many great videos on the Internet that explain things that even if you know the subject matter, it is fun to watch and see some of the great animations. For example [Sabin] has this beautifully animated explanation of how MOSFETs work that you can see below.

It uses the same basic graphics and style as his earlier video on bipolar transistors (second video, below) which is a great one to watch, too. In all fairness to your electronics teacher, the kind of graphics in these videos would have cost a fortune to do back in the 20th century — just watch some of the videos we talk about in some of our historical posts.

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Gamers Rejoice: Here’s a Fix for ASUS Strix Vega 64 Thermal Issues

Every year, we demand our computers to be ever faster, capable of delivering progressively more eye-watering graphics and doing it all as reliably as ever. Unfortunately, sometimes, new designs miss the mark. [Cloakedbug] was having issues with voltage regulator temperatures on an ASUS Strix VEGA 64 — one of the latest RADEON graphics cards on the market — and decided to investigate.

Right away, issues were apparent; one of the main thermal pads was making poor contact with the FETs it was intended to carry heat for, and was poorly sized to boot. In a show of poor quality, the pad wasn’t nicely sized for the aluminium plate it was attached to, and was applied in a rather haphazard manner. Suspecting this was perhaps one of the root causes of the card running hot, the decision was made to replace the pad with something more suitable.

Specifying a thicker pad that was properly sized to the heatsink plate was the order of the day, and a couple of other smaller heatsink pads were also replaced, all with Thermal Grizzly Minus Pad 8. [Cloakedbug] reports a temperature drop of over 30 degrees C under load on the VR SOC bank, down from 115 C initially. It sounds like this will go a long way to keeping the card happy and healthy over time. Looking around the web, there’s definitely a few reports of thermal issues out there, so this could be a useful fix if you’re having trouble with the same card at home.

In the end, it’s a simple, tidy fix to an expensive piece of hardware that really should have shipped with this sorted from the factory. We’ve seen a fair few thermal fixes over the years here, like this one involving a thermal camera as a diagnosis tool.

[Thanks to Keith O for the tip!]

Federico Faggin: The Real Silicon Man

While doing research for our articles about inventing the integrated circuit, the calculator, and the microprocessor, one name kept popping which was new to me, Federico Faggin. Yet this was a name I should have known just as well as his famous contemporaries Kilby, Noyce, and Moore.

Faggin seems to have been at the heart of many of the early advances in microprocessors. He played a big part in the development of MOS processors during the transition from TTL to CMOS. He was co-creator of the first commercially available processor, the 4004, as well as the 8080. And he was a co-founder of Zilog, which brought out the much-loved Z80 CPU. From there he moved on to neural networking chips, image sensors, and is active today in the scientific study of consciousness. It’s time then that we had a closer look at a man who’s very core must surely be made of silicon.

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Understanding a MOSFET Mixer

A mixer takes two signals and mixes them together. The resulting output is usually both frequencies, plus their sum and their difference. For example, if you feed a 5 MHz signal and a 20 MHz signal, you’d get outputs at 5 MHz, 15 MHz, 20 MHz, and 25 MHz. In a balanced mixer, the original frequencies cancel out, although not all mixers do that or, at least, don’t do it perfectly. [W1GV] has a video that explains the design of a mixer with a dual gate MOSFET, that you can see below.

The dual gate MOSFET is nearly ideal for this application with two separate gates that have effectively infinite input impedance. [Stan] takes you through the basic circuit and explains the operation in whiteboard fashion.

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