A Custom Built FPV Monitor to Keep the Fans Happy

If you’re going to be flying around a FPV-capable aircraft, be it a quadcopter or a fixed-wing plane, you shouldn’t be surprised if bystanders want to take a turn wearing your googles. Of course we hope that you’re good enough flying line of sight that you don’t need to be wearing the googles to stay airborne, but it does make it harder to pull off the sort of tricks and maneuvers that your audience wants to see. So if you want to put on a good show, the audience really needs their own display.

Unfortunately, as avid FPV flier [Michael Delaney] discovered, even the “cheap” ones will run you at least $100 USD. So he did what any self-respecting hacker would do, he set out to build his own. Using a collection of off the shelf components he was able to build a very impressive monitor that lets the viewer see through the eyes of his quadcopter at less than half the cost of commercially available offerings. Though even if he hadn’t manged to beat the cost of a turn-key monitor, we think it would have been more than worth it for this piece of highly customized gear.

At the heart of the monitor is a Boscam RX5808 5.8 GHz receiver, which is controlled by an Arduino Pro Mini. The video output from the receiver is sent to a 4.2″ TFT screen intended for the Raspberry Pi, and on the backside of the laser-cut wooden enclosure there’s a 128 x 64 I2C OLED to display the currently selected channel and diagnostic information.

An especially nice touch for this project is the custom PCB used to tie all the components together. [Michael] could have taken the easy route and sent the design out for fabrication, but instead went with the traditional method of etching his own board in acid. Though he did modernize the process a bit by using a laser and pre-sensitized copper clad board, a method that seems to be gaining in popularity as laser engravers become a more common component of the hacker’s arsenal.

We’ve previously covered using the RX5808 and Arduino combo to create a spectrum analyzer, in case you want to do more than just watch your friends do powerloops.

Look Upon Eyepot, And Weep For Mercy

Hope you weren’t looking forward to a night of sleep untroubled by nightmares. Doing his part to make sure  Lovecraftian mechanized horrors have lease in your subconscious, [Paul-Louis Ageneau] has recently unleashed the horror that is Eyepot upon an unsuspecting world. This Cycloptic four legged robotic teapot takes inspiration from an enemy in the game Alice: Madness Returns, and seems to exist for no reason other than to creep people out.

Even if you aren’t physically manifesting nightmares, there’s plenty to learn from this project. [Paul-Louis Ageneau] has done a fantastic job of documenting the build, from the OpenSCAD-designed 3D printed components to the Raspberry Pi Zero and Arduino Pro Mini combo that control the eight servos in the legs. If you want to play along at home all the information and code is here, though feel free to skip the whole teapot with an eyeball thing.

A second post explains how the code is written for both the Arduino and Pi, making for some very illuminating reading. A Python script on the Pi breaks down the kinematics and passes on the appropriate servo angles to the Arduino over a serial link. Combined with a web interface for control and a stream from the teapot’s Raspberry Pi Camera module, and you’ve got the makings of the world’s creepiest telepresence robot. We’d love to see this one stomping up and down a boardroom table.

Seems we are on a roll recently with creepy robot pals. Seeing a collaboration between Eyepot and JARVIS might be too much for us to handle. Though we have a pretty good idea how we’d want to control them.

 

Mini Spy Bug Walkthrough

What we like most about [GreatScott’s] project videos is that he not only shows making them but also the calculations for selecting parts and the modifications along the way. This time he’s made a mini spy bug that records up to nine hours of audio.

His first task was to figure out if the ATmega328p’s ADC is suitable for audio sampling, but only after he explains how sampling works by periodically checking the input voltage from the microphone. Checking the datasheet he found that the ADC’s fastest conversion time is 13 microseconds, which works out to a sampling rate of 76.923 kHz. Good enough.

He then walks through why and how he decided to go with a pre-made amplifier circuit built around the MAX9814 IC. Spoiler alert. His electret’s amplifier output voltage was too low, using an off-the-shelf circuit instead of making his own kept things simple, and the circuit has automatic gain control.

At this point, he added the MicroSD card adapter. Why not just transmit the audio over FM as so many others have done with their hacks? Perhaps he’s worried about someone detecting the transmission and finding his bug.

His final optimization involved getting a good battery life. He measured the circuit’s current draw at 20 milliamps. With a 160 mAh battery capacity, that would be 8 hours of recording time. Removing the Arduino Pro Mini’s voltage regulator and two LEDs got the current down to 18 milliamps and a recording time of 9 hours. Better.

Those are the highlights. Enjoy his full walkthrough in the video below.

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Sub-$20 Arduino-Based Telemetry System

[William Osman] set out to prove that unlike expensive commercial data logging rigs, he could get the same results for under twenty bucks. He wanted to build a wireless three-axis accelerometer for a race car project, allowing engineers to make modifications to the suspension based on the data collected.

The hardware consists of an Arduino Pro Mini connected to a three-axis accelerometer, and an nRF24L01 wireless module. Power is supplied by the race car’s 12 V, changed to 5 V by a linear regulator with the Pro Mini in turn supplying 3.3 V. The base station consists of an Arduino and another nRF24L01 module plugged into a laptop.

The telemetry system is based on COSMOS, an open-source, realtime datalogging platform put out by Bell Aerospace. COSMOS consists of fifteen separate applications depending on how you want to view and manage your telemetry. You can download [William]’s COSMOS config files and Arduino sketch on Google Docs.

We’ve published a bunch of pieces on telemetry, like this ESP8266 telemetry project, a rocket telemetry rig, and open sourcing satellite telemetry.

[Thanks, Dennis Nestor!]

Building a Self-Balancing Robot Made Easy

Not only has [Joop Brokking] built an easy to make balancing robot but he’s produced an excellent set of plans and software for anyone else who wants to make one too. Self-balancers are a milestone in your robot building life. They stand on two-wheels, using a PID control loop to actuate the two motors using data from some type of Inertial Measurement Unit (IMU). It sounds simple, but when starting from scratch there’s a lot of choices to be made and a lot of traps to fall into. [Joop’s] video explains the basic principles and covers the reasons he’s done things the way he has — all the advice you’d be looking for when building one of your own.

He chose steppers over cheaper DC motors because this delivers precision and avoids issues when the battery voltage drops. His software includes a program for getting a calibration value for the IMU. He also shows how to set the drive current for the stepper controllers. And he does all this clearly, and at a pace that’s neither too fast, nor too slow. His video is definitely worth checking out below.

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Ceiling Tiles Give it Up for Christmas LED Ornaments

The great thing about holidays is that they always seem to require some shiny things. The modern version of shiny things seems to be LEDs and advances in technology being what they are, we now have amazing programmable LEDs. And programmable LEDs mean animated shiny things! Years ago, [wpqrek] made an LED ornament using discrete components. This year he revisited his ornament and decided to make a new, animated, RGB ornament.

[Wpqrek]’s build is based around five WS2812b strips connected to an Arduino Pro Mini. The ornament itself is a thick styrofoam ceiling tile cut into a star shape with a red-painted wooden frame. Decorated with baubles and stars, the LED strips start in the center and end up at each point in the star. With each strip connected in parallel to the Pro Mini, [wpqrek] used the Arduino Light Animation library to handle the animations.

[Wpqrek] says the result is too big for his tree, so he uses it as a stand-alone ornament. Perhaps using lighter materials would help — or getting a bigger tree! Check out the Arduino lighting controller or the Trompe-l’oeil Menorah for more holiday hacks.

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