All posts by Jeremy Costin

Radio Frequency: Transmitter and Receiver

Radio Frequency: The Basics

Transmitter and Receiver: Two devices that are wired and programmed – a transmitter can be wired and programmed to send information to a receiver

Uses: communication between two devices – sending information from one device to another

Ex: Actual radios

How it applied to my project:

From the start of working on my project, I knew that I would need some way for two devices to communicate with each other, as my project was a device that enabled soldiers to both manually send alerts to local command centers with the push of a button and automatically send alerts, their location and their heart rate when their heart rate became dangerously high or low. Radio frequency seemed to be a good avenue through which to achieve this communication because not only did it appear to be a reliable way to send information from one device to another, but the range over which it could send this information was higher than alternative communication devices, and it was cheaper than other devices.

 

Successes Failures
Wired and programmed radio frequency to work with pushbutton to send an alert from the device with the transmitter to the serial monitor of the device with the receiver.

 

 

We were unable to get the radio frequency to work with a GPS to reliably send the location of the device with the transmitter to the device with the receiver.

At certain points, the radio frequency worked to send this information, but it was not consistent enough for our project.

Advice:

Though this is a cheap option when it comes to getting two devices to communicate with each other, it is not reliable. Look into other options before dedicating a significant amount of time to becoming familiar with this technology. Other good options include Wifi or X-bee, a similar form of communication (what I ultimately used for my project). If you do end up using radio frequency and you find that it is not working after some time, move on. The devices can be vey faulty, so do not waste too much time trying to get them to work.

 

How I learned how to use this:

When I first started using the radio frequency transmitter and receiver, I knew nothing about it. I did some online research to get a basic understanding of how they work. The CIJE Biomedical Engineering Textbook was a great resource/starting place to learn how to wire and program these devices. I relied on that as a foundation, and ultimately tweaked the wiring and code to fit my product’s need as I went along. Ms. Smith was also a great resource; she was very knowledgeable about how radio frequency works, and I learned a lot by working with her.

 

Helpful Links:

CIJE Biomedical Engineering Textbook

Radio Frequency Power Point

Information for Sparkfun Model

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written by Lulu Wein Class of 2017

Electret Microphone Amplifier – MAX4466 with Adjustable Gain

 

The adafruit Electret Microphone Amplifier is an amplifier attached to a sound sensor which can be used to record audio, change voices, and any sound reactive projects like mine. These small amplifiers were perfect because they do not take up much space in the project but they are able to do a lot. They can adjust the amount of sound input and output to a voltage that the Arduino can detect. I did a lot of research regarding these sensors and learned how to adjust the volume and use them for sound reactive devices. The first step is to solder the header pins that come with the sensor to the OUT, GND, and VCC breakout pins. If you need help soldering refer to the soldering How-to on the website : http://etoolbox.org/tools/soldering-2/ . ‎Edit When soldering, be very careful not to leave the soldering iron on the metal for too long because to avoid frying the board. Once it has cooled, use wires to connect the sensor to an Arduino board: GND to ground, VCC to the VCC pin (2.4-5V), and OUT to an analog pin. On the back of the board is a small trick pot (labeled below). Use a screwdriver to gently turn it to adjust the gain based on how loud the sounds you are inputing are. If you don’t adjust the gain, the sound wave could clip, altering your results. When I was doing this, I had to play around with the gain for a few classes before I finally found the perfect setting. If you are using multiple sensors, not all of them will work on the same setting, they will probably need to be turned different amounts. This is all of the hardware you need to set up before beginning your code.

 

screen-shot-2016-11-18-at-10-57-11-am

When writing your code, keep in mind that the sound is measured through the analog pins, so it is a sound wave. When a loud sound is sensed, the Arduino will read either a very high or very low value from 0-1023. If you are making an audio reactive project, you must write in the code that when a loud sound is sensed, some other component will complete an action. For example, if you wanted to turn an LED on when a sound is sensed:

if (sensorValue < 300 || sensorValue>700)         // If sound wave is at its extremes (loud sound)

{

digitalWrite (RedLED, HIGH); // Turn red LED on

}

 

The most important thing is to keep trying and never give up! Be fearless!!

GOOD LUCK!!!!!

Written by Tamar Kellner Class of 2018

Soldering

Soldering is a process in which two or more metal items are joined together by melting and then flowing a filler metal into the joint—the filler metal having a relatively low melting point.

Soldering is very helpful if you want to join two or more metal objects with a stronger bond than tape, for example, but not too strong, as applying some pressure can break a soldered bond. Soldering is very important because it creates a temporary bond that can then be placed in a product. In my project Visionary Inc.’s caneye we build a cane for blind people. In our project , we used soldering to connect all of the wiring (including to the ultrasonic sensors). It was vital in the creation of the caneye, as the sensor array would not function throughout the cane if we didn’t use soldering to extend the wires.

Here is a quick lesson on how to Solder:

– Make sure you have all the proper pieces

  • The solder
  • The iron
  • The Fan
  • Whatever two things you are desiring to solder
  • Then you turn on the iron and put it up to your desired temperature you want it (about 375 to 400 degrees)
  • Then you wait for the Iron to warm up
  • You then place some solder onto the iron just to prep it up for your soldering job.
  • Then you place the solder and the iron right near to the place that you need to connect together (like between two wires or between a wire and Arduino board to give two examples) also make sure to place both onto the location to put the solder on but do not have the iron and solder touching eachother – feel free to use clips provided at the soldering station in order to hold some of your pieces you want to solder in place
  • Then once the metal melts onto your desired location, make sure the solder is on there nicely
  • Then move on to the next place you need to solder

 

However, despite our eventual success, we originally struggled a bit with soldering, so here are some tips:

  • Make sure you are using the lead-free solder & the temperature of the iron is around 400
  • Try to stabilize the objects your soldering as much as possible, because if something moves while you are soldering, it is very likely you will make a mistake or be unsuccessful.
  • Make sure that the fan is on, as the fumes caused by soldering can be quite strong and can be dangerous. The fan will minimize the odor.
  • While soldering, be sure to keep your fingers/body as far away from the soldering as possible (make special note of where you’re holding the soldering iron), as touching either the iron or the hot metal can be very painful.
  • When soldering, first melt some solder onto the metal objects. Then, push the objects together, and use the soldering iron to melt the already placed solder together (if needed, add some more). This popular practice is known as tinning.
  • When finished, it can be very helpful to wrap a piece of electrical tape around the soldered objects, especially if you are planning on putting a lot wires close to each other.

 

We learned how to solder from two sources: Dr. Aviv provided us with advice as we went along, and the Internet. Here are some great YouTube videos that provide many important tips and tricks for soldering beginners:

 

Picture to get you familiar with soldering:

screen-shot-2016-11-16-at-3-29-27-pm

Written by Ben Glicksman Class of 2018