DIY RC Controller Built With Old-School Parts

March 20, 2024 by Lewin Day 16 Comments

Once upon a time, RC transmitters were expensive units that cost hundreds of dollars even at the low end. Now, you can get them pretty cheaply, or, you can choose to build your own. [Phytion] did just that.

The design isn’t based around a modern microcontroller, nor does it rely on WiFi or Bluetooth connections. Instead, it’s a little more old school. It’s built using the HT12E parallel-to-serial encoder chip, and the HT12D decoder chip for the receiver. The controller uses a pair of HT12Es on the transmitter, and a pair of HT12Ds on the receiver. These accept inputs from a pair of analog joysticks and encode them as serial data. However, they essentially just act as digital joysticks in this design. The HT12Es feed into an STX882 module which transmits the data from the HT12Es over 433 MHz. Another STX882 module receives this signal, and passes it through HT12Ds for decoding.

At the receiving end, one joystick can turn four outputs on or off depending on whether it is pushed up, down, left or right. A channel select switch then allows it to do the same for four further outputs. The second joystick just mirrors the operation of the first. It’s just intended to make controlling something like an RC car easier by allowing one stick to be pushed forwards and backwards, and the other left and right.

You don’t see many designs like this anymore. Realistically, it’s possible to get far more functionality out of a design based on an ESP32 or similar wireless-capable chip. However, this one doesn’t require any complicated handshaking and powers up instantly, which is a nice bonus. Plus, it’s always interesting to see alternative designs tried out in the wild. Video after the break.

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Fail Of The Week: The Little Remote-Controlled Snowblower That Couldn’t

March 3, 2024 by Dan Maloney 17 Comments

[Punxatawny Phil]’s prognostications aside, winter isn’t over up here in the Northern Hemisphere, and the snow keeps falling. If you’re sick of shoveling the driveway and the walk and you don’t have a kid handy to rope into the job, relax — this rapidly assembled junkyard RC snowblower will do just as crappy a job while you stay nice and warm inside.

This build seemed to have a lot of potential at the start, based as it was on a second-hand track-drive snowblower, something that was presumably purpose-built for the job at hand. [Lucas] quickly got to work on it; he left the original gasoline engine to power the auger but took most of the transmission off so that each track could be driven separately with a wheelchair motor. That seemed like a solid idea as far as steering goes, but the fact that he chose to drive the 24 volt motors with a single 12 volt deep-cycle battery worked against him out in the snow.

With a battery upgrade for better traction, the snowblower actually got around in the snow pretty well. [Lucas] also added some nice features, like a linear actuator to remotely engage the auger — a nice safety touch when kids and pets are around — and a motor to control the direction of the chute. Even these improvements weren’t enough, though; it worked insofar as it moved snow from where it was to where it wasn’t, but didn’t really move it very far. To the casual observer, it seems like there’s just not enough weight to the machine, allowing it to ride up over the snow rather than scraping the driveway clean. Check out the video below and see what you think.

Now, we’re not picking on [Lucas] here. Far from it — we enjoyed this build as much as some of his other stuff, like his scratch-built CO2 laser tube and his potty-mouthed approach to Kaizen tool organization. We still think this one has a lot of potential, and we’re glad he vowed to continue working on it for next winter.

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No Inductors Needed For This Simple, Clean Twin-Tee Oscillator

February 18, 2024 by Dan Maloney 11 Comments

If there’s one thing that amateur radio operators are passionate about, it’s the search for the perfect sine wave. Oscillators without any harmonics are an important part of spectrum hygiene, and while building a perfect oscillator with no distortion is a practical impossibility, this twin-tee audio frequency oscillator gets pretty close.

As [Alan Wolke (W2AEW)] explains, a twin-tee oscillator is quite simple in concept, and pretty simple to build too. It uses a twin-tee filter, which is just a low-pass RC filter in parallel with a high-pass RC filter. No inductors are required, which helps with low-frequency designs like this, which would call for bulky coils. His component value selections form an impressively sharp 1.6-kHz notch filter about 40 dB deep. He then plugs the notch filter into the feedback loop of an MCP6002 op-amp, which creates a high-impedance path at anything other than the notch filter frequency. The resulting sine wave is a thing of beauty, showing very little distortion on an FFT plot. Even on the total harmonic distortion meter, the oscillator performs, with a THD of only 0.125%.

This video is part of [Alan]’s “Circuit Fun” series, which we’ve really been enjoying. The way he breaks complex topics into simple steps that are easy to understand and then strings them all together has been quite valuable. We’ve covered tons of his stuff, everything from the basics of diodes to time-domain reflectometry.

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Hot Wheel Car Becomes 1/64 Scale Micro RC Car, Complete With Camera

November 13, 2023 by Donald Papp 20 Comments

If you enjoy watching skilled assembly of small mechanical systems with electronics to match, then make some time to watch [Max Imagination] transform a Hot Wheels car into a 1/64th scale RC car complete with video FPV video feed. To say the project took careful planning and assembly would be an understatement, and the results look great.

The sort of affordable electronics available to hobbyists today opens up all kinds of possibilities, but connecting up various integrated modules brings its own challenges. This is especially true when there are physical constraints such as fitting everything into an off-the-shelf 1/64 scale toy car.

There are a lot of interesting build details that [Max] showcases, such as rebuilding a tiny DC motor to have a longer shaft so that it can drive both wheels at once. We also liked the use of 0.2 mm thick nickel strips (intended for connecting cells in a battery pack) as compliant structural components.

There are actually two web servers being run on the car. One provides an interface for throttle and steering (here’s the code it uses), and the other takes care of the video feed with ESP32-CAM sending a motion jpeg stream. [Max]’s mobile phone is used to control the car, and a second device goes into an old phone-based VR headset to display the FPV video feed.

Circuit diagrams and code are available for anyone wanting to perhaps make a similar project. We’ve seen micro RC builds of high quality before, but integrating an FPV camera kicks things up a notch. Want even more complex builds? All the rules change when weight reduction is a non-negotiable #1 priority. Check out a micro RC plane that weighs under three grams and get a few new ideas.

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Fly Like You Drive With This Flying RC Drift Car

May 26, 2023 by Dan Maloney 9 Comments

So it’s 2023, and you really feel like we should have flying cars by now, right? Well, as long as you ignore the problem of scale presented by [Nick Rehm]’s flying RC drift car, we pretty much do.

At first glance, [Nick]’s latest build looks pretty much like your typical quadcopter. But the design has subtle differences that make it more like a car without wheels. The main difference is the pusher prop at the aft, which provides forward thrust without having to pitch the entire craft. Other subtle clues include the belly-mounted lidar and nose-mounted FPV camera, although those aren’t exactly unknown on standard UAVs.

The big giveaway, though, is the RC car-style remote used to fly the drone. Rather than use the standard two-joystick remote, [Nick] rejiggered his dRehmFlight open-source flight control software to make operating the drone less like flying and more like driving. The lidar is used to relieve the operator of the burden of altitude keeping by holding the drone at about a meter or so off the deck. And the video below shows it doing a really good job of it, for the most part — with anything as complicated as the multiple control loops needed to keep this thing in the air, it’s easy for a sudden input to confuse things.

We have to admit that [Nick]’s creation looks like a lot of fun to fly, or drive — whichever way you want to look at it. Either way, we like the simplification of the flight control system and translating the driving metaphor into flying — it seems like that’ll be something we need if we’re ever to have full-size flying cars.

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Remote-Controlled Hypercar Slices Through Air

May 23, 2023 by Bryan Cockfield 17 Comments

Almost all entry-level physics courses, and even some well into a degree program, will have the student make some assumptions in order to avoid some complex topics later on. Most commonly this is something to the effect of “ignore the effects of wind resistance” which can make an otherwise simple question in math several orders of magnitude more difficult. At some point, though, wind resistance can’t be ignored any more like when building this remote-controlled car designed for extremely high speeds.

[Indeterminate Design] has been working on this project for a while now, and it’s quite a bit beyond the design of most other RC cars we’ve seen before. The design took into account extreme aerodynamics to help the car generate not only the downforce needed to keep the tires in contact with the ground, but to keep the car stable in high-speed turns thanks to its custom 3D printed body. There is a suite of high-speed sensors on board as well which help control the vehicle including four-wheel independent torque vectoring, allowing for precise control of each wheel. During initial tests the car has demonstrated its ability to corner at 2.6 lateral G, a 250% increase in corning speed over the same car without the aid of aerodynamics.

We’ve linked the playlist to the entire build log above, but be sure to take a look at the video linked after the break which goes into detail about the car’s aerodynamic design specifically. [Indeterminate Design] notes that it’s still very early in the car’s development, but has already exceeded the original expectations for the build. There are also some scaled-up vehicles capable of transporting people which have gone to extremes in aerodynamic design to take a look at as well.

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Hackaday Prize 2023: Tiny RC Aircraft Built Using Foam And ESP12

April 29, 2023 by Lewin Day 13 Comments

Once upon a time, a radio controlled plane was a hefty and complex thing. They required small nitro engines, support equipment, and relatively heavy RC electronics. Times have changed since then, as this lightweight RC build from [Ravi Butani] demonstrates.

The body of the plane is lightweight foam, and can be assembled in two ways. There’s a relatively conventional layout, using a main wing, tailplane, and rudder, or a pusher model with the main wing at the rear and a canard up front. The open hardware electronics package, which [Ravi] calls VIMANA, consists of an ESP12 module with a pair of MOSFETs to act as two independent motor drivers — allowing the plane to be flown and steered with differential thrust.

For more advanced flight control, it can also command a pair of servos to control ailerons, a rudder, canards, or elevons, depending on configuration. There’s also potential to install an IMU to set the plane up with flight stabilization routines.

Thanks to the low-cost of the VIMANA board, [Ravi] hopes it can be used in STEM education programs. He notes that it’s not limited just to aircraft, and could be used for other motorized projects such as boats and cars. We’ve featured an early version of his work before, but the project has come a long way since then.

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