Chinese Regulators May Kill Retractable Car Door Handles That Never Should Have Existed

November 26, 2025 by Lewin Day 157 Comments

Headlights. Indicators. Trunk releases. Seatbelts. Airbags. Just about any part of a car you can think of is governed by a long and complicated government regulation. It’s all about safety, ensuring that the car-buying public can trust that their vehicles won’t unduly injure or maim them in regular operation, or in the event of accident.

However, one part of the modern automobile has largely escaped regulation—namely, the humble door handle. Automakers have been free to innovate with new and wacky designs, with Tesla in particular making waves with its electronic door handles. However, after a series of deadly incidents where doors wouldn’t open, regulators are now examining if these door handles are suitable for road-going automobiles. As always, regulations are written in blood, but it raises the question—was not the danger of these complicated electronic door handles easy to foresee?

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A Look Inside A Lemon Of A Race Car

May 21, 2025 by Fenix Guthrie 7 Comments

Automotive racing is a grueling endeavor, a test of one’s mental and physical prowess to push an engineered masterpiece to its limit. This is all the more true of 24 hour endurance races where teams tag team to get the most laps of a circuit in over a 24 hour period. The format pushes cars and drivers to the very limit. Doing so on a $500 budget as presented by the 24 hours of Lemons makes this all the more impressive!

Of course, racing on a $500 budget is difficult to say the least. All the expected Fédération Internationale de l’Automobile (FIA) safety requirements are still in place, including roll cage, seats and fire extinguisher. However, brakes, wheels, tires and safety equipment are not factored into the cost of the car, which is good because an FIA racing seat can run well in excess of the budget. Despite the name, most races are twelve to sixteen hours across two days, but 24 hour endurance races are run. The very limiting budget and amateur nature of the event has created a large amount of room for teams to get creative with car restorations and race car builds.

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Lost Foam Aluminium Alloy Casting

February 28, 2025 by Dave Rowntree 21 Comments

[Kelly Coffield] makes intake manifolds for old Ford throttle bodies for fun, demonstrating an excellent technique for making such things in the small shop. The mould patterns are CNC machined from a solid polystyrene block, with all the necessary gates to feed the aluminium into the mould. The principle is to introduce aluminium from a large central runner into the mould structure, which feeds the gates into the mould parts. The various foam mould components are then glued with an extra brace bar at the bottom to strengthen it.

The complete structure is then sprayed with surfactant (just plain old soapy water) and dip-coated in a refractory slurry. The surfactant adjusts the coating’s surface tension, preventing bubbles from forming and ruining the surface quality produced by this critical coating step.

Once a satisfactory coating has been applied and hardened, the structure is placed inside a moulding pan fitted with a pneumatic turbine vibrator, to allow sand to be introduced. The vibrations ease the flow of sand into all the nooks and crannies, fully supporting the delicate mould structure against the weight of the metal, and gases produced as the foam burns away. A neat offset pouring cup is then added to the top of the structure and packed in with more sand to stabilise it. It’s a simple setup that can easily be replicated in any hackerspace or backyard for those motivated enough. [Kelly] is using A356 aluminium alloy, but there’s no reason this technique won’t work for other metals.

It was amusing to see [Kelly] demould by just dumping out the whole stack onto the drive and throwing the extracted casting into a snow bank after quenching. We might as well use all that free Midwest winter cooling capacity! After returning to the shop, [Kelly] would typically perform any needed adjustments, such as improving flatness in the press, while the part was in the ‘as cast temper’ condition. We’ll gloss over the admission of cutting the gates off on the table saw! After these adjustments, the part is artificially aged to a T5-like specification, to give it its final strength and machinability properties. There are plenty more videos on this process on the channel, which is well worth a look.

Aluminium casting is nothing new here, here’s a simple way to cast using a 3D printed pattern. But beware, casting aluminum can be hazardous, it does like to burn.

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A Brand-New Additive PCB Fab Technique?

October 27, 2024 by Dan Maloney 68 Comments

Usually when we present a project on these pages, it’s pretty cut and dried — here’s what was done, these are the technologies used, this was the result. But sometimes we run across projects that raise far more questions than they answer, such as with this printed circuit board that’s actually printed rather than made using any of the traditional methods.

Right up front we’ll admit that this video from [Bad Obsession Motorsport] is long, and what’s more, it’s part of a lengthy series of videos that document the restoration of an Austin Mini GT-Four. We haven’t watched the entire video much less any of the others in the series, so jumping into this in the middle bears some risk. We gather that the instrument cluster in the car is in need of a tune-up, prompting our users to build a PCB to hold all the instruments and indicators. Normally that’s pretty standard stuff, but jumping to the 14:00 minute mark on the video, you’ll see that these blokes took the long way around.

Starting with a naked sheet of FR4 substrate, they drilled out all the holes needed for their PCB layout. Most of these holes were filled with rivets of various sizes, some to accept through-hole leads, others to act as vias to the other side of the board. Fine traces of solder were then applied to the FR4 using a modified CNC mill with the hot-end and extruder of a 3D printer added to the quill. Components were soldered to the board in more or less the typical fashion.

It looks like a brilliant piece of work, but it leaves us with a few questions. We wonder about the mechanics of this; how is the solder adhering to the FR4 well enough to be stable? Especially in a high-vibration environment like a car, it seems like the traces would peel right off the board. Indeed, at one point (27:40) they easily peel the traces back to solder in some SMD LEDs.

Also, how do you solder to solder? They seem to be using a low-temp solder and a higher temperature solder, and getting right in between the melting points. We’re used to seeing solder wet into the copper traces and flow until the joint is complete, but in our experience, without the capillary action of the copper, the surface tension of the molten solder would just form a big blob. They do mention a special “no-flux 96S solder” at 24:20; could that be the secret?

We love the idea of additive PCB manufacturing, and the process is very satisfying to watch. But we’re begging for more detail. Let us know what you think, and if you know anything more about this process, in the comments below.

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Fundamentals Of FMCW Radar Help You Understand Your Car’s Point Of View

October 19, 2024 by Dan Maloney 3 Comments

Pretty much every modern car has some driver assistance feature, such as lane departure and blind-spot warnings, or adaptive cruise control. They’re all pretty cool, and they all depend on the car knowing where it is in space relative to other vehicles, obstacles, and even pedestrians. And they all have another thing in common: tiny radar sensors sprinkled around the car. But how in the world do they work?

If you’ve pondered that question, perhaps after nearly avoiding rear-ending another car, you’ll want to check out [Marshall Bruner]’s excellent series on the fundamentals of FMCW radar. The linked videos below are the first two installments. The first covers the basic concepts of frequency-modulated continuous wave systems, including the advantages they offer over pulsed radar systems. These advantages make them a great choice for compact sensors for the often chaotic automotive environment, as well as tasks like presence sensing and factory automation. The take-home for us was the steep penalty in terms of average output power on traditional pulsed radar systems thanks to the brief time the radar is transmitting. FMCW radars, which transmit and receive simultaneously, don’t suffer from this problem and can therefore be much more compact.

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Building An Automotive Load Dump Tester

October 13, 2024 by Dave Rowntree 11 Comments

For those who have not dealt with the automotive side of electronics before, it comes as somewhat of a shock when you find out just how much extra you have to think about and how tough the testing and acceptance standards are. One particular test requirement is known as the “load dump” test. [Tim Williams] needed to build a device (first article of three) to apply such test conditions and wanted to do it as an exercise using scrap and spares. Following is a proper demonstration of follow-through from an analytical look at the testing specs to some interesting hand construction.

The load dump test simulates the effect of a spinning automotive alternator in a sudden no-load scenario, such as a loose battery terminal. The sudden reduction in load (since the battery no longer takes charging current) coupled with the inductance of the alternator windings causes a sudden huge voltage spike. The automotive standard ISO 7637-2:2011 dictates how this pulse should be designed and what load the testing device must drive.

The first article covers the required pulse shape and two possible driving techniques. It then dives deep into a case study of the Linear Tech DC1950A load dump tester, which is a tricky circuit to understand, so [Tim] breaks it down into a spice model based around a virtual transistor driving an RC network to emulate the pulse shape and power characteristics and help pin down the specs of the parts needed. The second article deals with analysing and designing a hysteric controller based around a simple current regulator, which controls the current through a power inductor. Roughly speaking, this circuit operates a bit like a buck converter with a catch diode circulating current in a tank LC circuit. A sense resistor in the output path is used to feedback a voltage, which is then used to control the driving pulses to the power MOSFET stage. [Tim] does a good job modeling and explaining some of the details that need to be considered with such a circuit.

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Junk Bin Build Lets You Test Fuel Injectors On The Cheap

July 30, 2024 by Dan Maloney 32 Comments

Fiddle around with cars long enough and you’ll realize two things: first, anything beyond the simplest repairs will probably require some kind of specialized tool, and second, those tools can be prohibitively expensive. That doesn’t mean you’re out of luck, though, especially if you’ve got scrap galore and a DIY spirit, as this junk bin fuel injector test stand ably demonstrates.

[Desert Rat Racer]’s test rig is designed to support four injectors at once and to test them under conditions as close as possible to what they’ll experience when installed. To that end, [Rat] mounted a junk intake manifold to a stand made from scrap wood and metal found by the side of the road. A pickle jar serves as a reservoir for the test fluid — he wisely used mineral spirits as a safer substitute for gasoline — and a scrap electric fuel pump pressurizes a junk fuel rail, which distributes fuel to the injectors under test.

For testing, the injectors are wired up to an electric injector tester, which is one of the few off-the-shelf components in the build. The fuel pump and injectors are powered by the 12 volt rail of a scrapped PC power supply. Just being able to watch the spray pattern is often enough to find a faulty injector, but in case a more quantitative test is indicated, each injector is positioned over a cheap glass cylinder to catch the test fluid, and scraps of a tape measure are used to measure the depth of the collected fluid. No fancy — and expensive — graduated cylinders required.

While we truly respect the hackiness of [Desert Rat Racer]’s build, the concept of avoiding buying tactical tools is foreign to us. We understand the logic of not dropping a ton on a single-use tool, but where’s the fancy blow-molded plastic case?

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