What does it do?
In this project I will
In this project I will
It’s been said that the best way to tackle the issue of childhood obesity would be to hook those children’s video game consoles up to a pedal-powered generator. Of course, this was said by [Alex], the creator of Cykill. Cykill interfaces an Xbox to an exercise bike, so to keep the video game going you’ll have to keep pedaling the bike.
While there is no generator involved in this project, it does mimic the effect of powering electronics from a one. The exercise bike has a set of communications wires, which are connected to a relay on the Xbox’s power plug. When the relay notices that the bike isn’t being pedaled enough, it automatically cuts power to the console. Of course, the risk of corrupting a hard drive is high with this method, but that only serves to increase the motivation to continue pedaling.
The project goes even further in order to eliminate temptation to bypass the bike. [Alex] super-glued the plug of the Xbox to the relay, making it extremely difficult to get around the exercise requirement. If you’re after usable energy instead of a daily workout, though, there are bikes out there that can power just about any piece of machinery you can imagine.
In this tutorial, I will be evaluating Prextron CHAIN blocks – a new system that allows you to connect your sensors and actuators to an Arduino NANO using clever 3D-printed prototyping boards that can be stacked sideways. This very modular system makes it easy to connect, disconnect and replace project components, and eliminate the “rats nest of wires” common to many advanced Arduino projects. CHAIN BLOCKS are open, which means that you can incorporate any of your sensors or actuators to these prototyping boards, and you can decide which specific pin on Arduino you plan to use. The CHAIN BLOCK connections prevent or reduce common connection mistakes, which make them ideal for class-room projects and learning activities.
I am going to set up a project to put these CHAIN BLOCKs to the test:
When I place my hand in-front of an Ultrasonic sensor, the Arduino will transmit a signal wirelessly to another Arduino, and consequently turn on a motor.
You need the following Prextron Chain Blocks
This project does not use any libraries. However, you will need to upload Arduino code to the Arduino. For this you will need the Arduino IDE which can be obtained from the official Arduino website:
The purpose of this project was to evaluate Prextron CHAIN BLOCKs and put them to the test. Here is what I thought of CHAIN BLOCKS at the time of evaluation. Some of my points mentioned below may no longer apply to the current product. It may have evolved / improved since then. So please take that into consideration
Thank you very much to Prextron for providing the CHAIN BLOCKS used in this tutorial, and allowing me to try out their product. If you are interested in trying them yourself, then make sure to visit them at:
The time for putting up festive lights all around your house is nigh, and this is a very popular time for those of us who use the holiday season as an excuse to buy a few WiFi chips and Arduinos to automate all of our decorations. The latest in this great tradition is [Real Time Logic]’s cloud-based Christmas light setup.
In order to give public access to the Christmas light setup, a ESP8266 WiFi Four Relay board was configured with NodeMCU. This allows for four channels for lights, which are controlled through the Light Controller Server software. Once this is setup through a domain, all anyone has to do to change the lighting display is open up a web browser and head to the website. The creators had homeowners, restaurants, and church displays in mind, but it’s not too big of a leap to see how this could get some non-holiday use as well.
The holidays are a great time to get into the hacking spirit. From laser-projected lighting displays to drunk, animatronic Santas, there’s almost no end to the holiday fun, and you’ve still got a week! (Or 53!)
I have a good background working with high voltage, which for me means over 10,000 volts, but I have many gaps when it comes to the lower voltage realm in which RC control boards and H-bridges live. When working on my first real robot, a BB-8 droid, I stumbled when designing a board to convert varying polarities from an RC receiver board into positive voltages only for an Arduino.
Today’s question is, how do you convert a negative voltage into a positive one?
In the end I came up with something that works, but I’m sure there’s a more elegant solution, and perhaps an obvious one to those more skilled in this low voltage realm. What follows is my journey to come up with this board. What I have works, but it still nibbles at my brain and I’d love to see the Hackaday community’s skill and experience applied to this simple yet perplexing design challenge.
I have an RC receiver that I’ve taken from a toy truck. When it was in the truck, it controlled two DC motors: one for driving backwards and forwards, and the other for steering left and right. That means the motors are told to rotate either clockwise or counterclockwise as needed. To make a DC motor rotate in one direction you connect the two wires one way, and to make it rotate in the other direction you reverse the two wires, or you reverse the polarity. None of the output wires are common inside the RC receiver, something I discovered the hard way as you’ll see below.
I wasn’t using the RC receiver with the toy truck. I extracted it from the truck and was using it to control my BB-8 droid. My BB-8 droid has two motors configured as what in the BB-8 builders world is called a hamster drive, though is more widely known as a tank drive or differential drive (see the illustrations). Rotate both wheels in the same direction with respect to the droid and the droid moves in that direction. Reverse both wheels and it drives in the opposite direction. Make the wheels rotate in opposite directions and it turns on the spot.
The motors in my BB-8 are drill motors and are controlled by two H-bridge boards. An Arduino does pulse width modulation to the H-bridge boards for speed control, and controls which direction the motors should turn. Finally, the RC receiver is what tells the Arduino what to do. But a converter board, the subject of this article, is needed between the RC receiver and the Arduino. Note that the Arduino is necessary also for countering when the BB-8 droid wobbles and for synchronizing sounds with the movement, but those aren’t addressed here.
Since there are two motors and two directions for each motor, the RC receiver needs to control four pins on the Arduino to make the two drill motors behave as follows: motor 1/clockwise, motor 1/counterclockwise, motor 2/clockwise, motor 2/counterclockwise. And whatever voltages the receiver puts on those pins has to be relative to the Ardunio’s ground.
And herein lies the problem. The Arduino expects positive voltages with respect to its ground on all those pins. So I needed a way to map the RC receiver’s two sets of motor control wires, which can have either positive or negative voltages across them, to the Arduino pins which only want positive voltages. And remember, none of those RC receiver wires are common inside the receiver.
Now, keep in mind, electronics is a general interest of mine and except for what we were taught in high school physics class, I’m self-taught. That means I’ve “read ahead” but much of my knowledge has been determined by what projects I’ve done. So I have gaps in my knowledge. I’d never turned negative voltages into positive before. It sounded simple enough. Searching online didn’t help though. The closest I got was in two old posts in forums where the answers were “It’s easy to do. I can do it with a single resistor.” But there was no further explanation and I didn’t ask my own question anywhere at that point.
Instead I came up with my own approach with just one set of wires from the RC receiver first. The wires coming from the receiver were blue and brown and could have either polarity depending on which way the receiver is being told to rotate the motor: clockwise or counterclockwise. That meant I needed two diodes to create two possible paths for the different polarities the brown wire could be: positive or negative. I then added a battery for the one path that was negative, to turn it into a positive.
Next, I put a PNP transistor between the positive of the battery and the receiver. With no signal from the RC transmitter, the transistor’s base is negative with respect to the emitter, but not enough to turn the transistor on. That’s because the battery’s negative is connected to the receiver’s blue wire and since there’s no signal from the transmitter, the brown wire is also at the same potential as the blue wire, and with battery negative.
The idea was that when the transmitter sent a signal to make that brown wire negative with respect to the blue wire, it would become even more negative and turn on the PNP transistor. A positive signal would then go from the battery, through the transistor to the Arduino.
The most obvious problem was that the Arduino wanted to see 3 volts to register as a HIGH input, meaning the battery would have to be at least 3 volts and so even with no signal from the transmitter, that would be -3 volts to the transistor, turning it on when it wasn’t supposed to be on.
And so I immediately thought of using a relay instead. I’d use the current running through the negative path to energize the relay, closing a switch that was completely independent of the RC receiver. The Arduino has a 5V output pin, so I made that switch close a circuit between the 5V pin and the Arduino’s pin 7, giving pin 7 the needed positive voltage.
The 1 in the circle in the schematic shows where I wanted to put a resistor in order to limit the current going through the relay’s coil. However, I tried with resistors all the way down to 4.7 ohms but the coil didn’t have enough current to close the switch. With no resistor, it worked and the current was 70mA. The relay’s coil was rated for 3V/120mA so I left it.
Using a relay did seem very heavy-handed, but it was the only solution I could come up with and I already had the relay in stock.
The next step was to add a second relay, doing the same for the second set of wires coming from the RC receiver for the second motor.
But the behavior was seemingly sporadic. And keep in mind that there was a whole dual H-bridge circuit that was also connected to the Arduino’s ground. I’d worked with relays a lot before, and the RC receiver came from a commercially made and functional toy so I had no reason to suspect that. On the other hand, I’d made the H-bridge circuit from scratch since I already had most of the parts, and I was new to H-bridges and MOSFETs. So at first I spent a good two weeks of spare time thinking my problem was with the H-bridge and drill motor side. I’m sure we’ve all experienced the same blindness, thinking the most likely culprit is the part you had a hand in.
But at some point I disconnected the H-bridge and tested just the RC receiver circuit, watching the voltages at the Arduino pins while I remotely turned on both “motors” in both directions in all combinations (no motors were connected at the time though). The only odd behavior I saw was when I turned the motors on in opposite directions.
Notice in the schematic that I’d connected together both blue wires coming from the RC receiver. Up to that point I’d been assuming that the blue wires were common inside the receiver and that it was only the brown wires that switched from positive to negative with respect to the blue wires. From the behavior I was seeing it looked like both wires were switching polarity, possibly around some other internal common reference.
So I added a third relay on one of the positive paths of one of the sets of wires. That meant the corresponding blue wire no longer needed to be grounded, keeping both of the receiver’s blue wires separate. Note that I didn’t bother putting in a fourth relay for the remaining positive path, and it turned out to not be necessary. At that point the circuits worked great and continue to do so.
And so I ask, is there a better way to convert the RC receiver output to something the Arduino can use? Relays require power, so it would be nice if there was a solution that didn’t require any extra power. My relay solution seems very early 1900s. Or maybe it’s a good solution after all, but just one of many. Let us know in the comments below.
After printing pieces to Prusa I3 is the new 4-legged spider with bluetooth comm :)
My attention is drawn towards the noise behind me....
I cannot believe it.
There it is.
The Arduino is taking a SELFIE !!
How did this happen?
Well actually, it is not that difficult for an Arduino.
I found out that my Canon Powershot SX50 HS camera has a port on the side for a remote switch. In the "Optional Accessories" section of the camera brochure, it identifies the remote switch model as RS-60E3. I then looked up the model number on this website to find out the size of the jack (3 core, 2.5mm), and the pinout (Ground, focus and shutter) required to emulate the remote switch. Once I had this information, I was able to solder some really long wires to the jack and connect up the circuit (as described below).
By connecting up the camera to an Arduino, the camera just got smarter !!
The Arduino connects to 2 different channels on the relay board in order to control the focus and the shutter of the camera. The relays are used to isolate the camera circuit from that of the Arduino. I have also included a couple of diodes and resistors in the circuit as an extra precaution, however they may not be needed.
Warning : Any circuit you build for your camera (including this one) is at your own risk. I will not take responsibility for any damage caused to any of your equipment. Do your research, and take any precautions you see fit.
However, if you do not have a google profile...
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Please make sure that you read and understand how your relay/relay module board works, the voltage and current it is rated for, and the risks involved in your project BEFORE you even attempt to start putting it together. Seek professional and qualified assistance BEFORE you undertake ANY high power projects.
If you choose to follow the instructions in this tutorial, you do so at your own risk. I am not an electrician, and am not a qualified electrical engineer - so please do your research and seek advice BEFORE undertaking a project using a relay. Please check your connections and test them BEFORE turning the power on.
I accept no responsibility for your project, or the risk/damage/fire/shock/injury/death/loss that it causes. You take full responsibility for your actions/project/creation, and do so at YOUR OWN RISK !!!
Please note: It is illegal in some countries to wire up a high power project without an electrician. Please check your country's rules/laws/regulations before you undertake your project. If you have any doubts - don't do it.
The Red light on the Relay board turns on when power is applied (via the VCC pin). When power is applied to one of the Channel pins, the respective green light goes on, plus the relevant relay will switch from NC to NO. When power is removed from the channel pin, the relay will switch back to NC from NO. In this sketch we see that power is applied to both LEDs in the setup() method. When there is no power applied to the CH1 pin, the yellow LED will be on, and the Green LED will be off. This is because there is a break in the circuit for the green LED. When power is applied to CH1, the relay switches from NC to NO, thus closing the circuit for the green LED and opening the circuit for the yellow LED. The green LED turns on, and the yellow LED turns off.
I also show what happens when you apply power to a channel (eg. CH3) when there is nothing connected to the relay terminals. The respective onboard LED illuminates. This is useful for troubleshooting the relays, and knowing what state the relay is in (NC or NO). NC stands for Normally closed (or normally connected) NO stands for Normally open (or normally disconnected)
Here is a circuit diagram for two of the relays on the relay module (CH1 and CH2).
This was taken from the iteadstudio site.
What do you do if you suck at a smartphone game? Buy some in-game upgrades to pretend like you’re good? Screw that! [Valentin] did what any self-respecting hacker would: developed an automated system to play for him.
Granted, when you see the demo video embedded below you’ll realize there isn’t much strategy involved in this game. But that setup to simulate the touchscreen presses is pretty neat. We’re used to seeing mechanical touchscreen hacks but this one is electronic, using a couple of pads of copper foil tape and some relays to make it happen. Here’s the one caveat: you still need to be touching something with your hand. This just uses the relays to switch the connection between the pads and your body.
We’ve looked around for this before. Does anyone have a cheap, simple, and effective hack to fully automate presses on a modern touchscreen? Can we use a potato or something? Tell us below, but send it in to the tips line too!