IR Controlled Car

Today I want to talk a little about DC motors. DC motors are a simple way to make objects move such as robots. One draw back of the DC motor is that it takes a lot of power to run. Meaning it takes a lot of energy to get it running at all. So if I wanted to make a robot that was battery powered I would somehow need to make these DC motors efficient. A really practical DC motor that a lot of people use when efficiency is needed is the solar DC motor. This motor runs fine with much less power than the standard current hogging motor. In my case I realized I needed a solar DC motor if I was to pull off a robot that lasted for a relatively long time.
Now after I had decided on my right motor I could get to the IR remote control part. The last couple blogs I talked about IR signals and what you could use them for. In this segment I want to use IR signals to control the direction of a robot. So say for instance if I pressed the up button on the remote control the controller would send a specific frequency that would turn on the motors to go forward. The brain of the robot would receive specific signals from the remote and act accordingly. So in this case my remote should have four different signals, each representing a command for the robot to go forward, backward, left or right. From this standpoint I could easily make an remote controlled car with four different oscillator signals and a robot that interpreted four different IR signals. What a cool idea!

Video of IR Detector

In this video I will be showing you how I came up with the idea and how I implemented it. I found out that IR technology is really cool stuff and there are endless possibilities of stuff you can do with it. Take what I did with this project and try to make it even better. Enjoy!

IR Sensor from Peter Morley on Vimeo.

Autonomous Bot

Have you ever seen one of those vacuum cleaner robots that move around the house on their own and do their cleaning? Well I have and they really didn't capture my attention until I realized I could make something similar to it with a different take on it. I came up with the idea of taking an IR emitter and an IR detector and angling them towards each other but not directly at each other. So whenever the vehicle came up to an obstacle the light from the emitter would deflect off the boundary and hit the detector and the motor would stop. Essentially the circuit made the motor run continually until the bot came upon an object.

I setup the IR emitter to emit a beam of light at a frequency of 38 Khz. I set the frequency using a 555 timer which is a clock that controls how many electric pulses get emitted per second. Once I had my emitter setup I could now start playing with my IR detector portion. To setup the IR detector I first had to get a detector that did what I wanted it to do when 38 KHz was pulsed at it. I found a good detector that allowed a voltage to leak through whenever a 38KHz light was hitting it. Then I had to pop the voltage even higher for it to work in a logic gate that is called an inverter. I amplified the voltage using a comparator circuit. Once the voltage was high enough I inverted it so the motor would get 0 current and 0 voltage. Basically the motor would run continuously until the IR detector received a 38KHz beam. Once I had it setup it was time to implement it and the next post will show you how I set it up on my prototyping breadboard.

Infrared Technology

I finally decided I would get my hands on some IR technology and make something with it. Today I will be explaining how infrared light technology works. Look around you and you can see hundreds or even thousands of different colors. The colors we see are a type of light that are within the visible spectrum. What a lot of people don't realize is that there is light all around us that is not visible to the human eye. Radiation is a form of light we can't see and one type of radiation we get is the sun's rays that can cause skin cancer. Those sun rays that are harmful are called ultra-violet rays and you have probably heard about them. So at this point hopefully you understand that there is visible light (very small spectrum) and invisible light (very large spectrum). Most of the light in the universe can not be seen by the human eye so we are left with only a small "bandwidth" of light but it is quite beautiful as we all know. Infrared light is a type of light we can't see and we will be using it in an experiment.

The experiment I will talk about has to do with receiving frequencies of light. I will have an emitter that emits light at a certain frequency so we can pretend our emitter is a sun that emits only one frequency. Our detector will act as an eye ball that can only one color. Another words the detector can only see one color so the detector only gets alerted when our emitter shoots a beam of light at it. The eyeball filters out every single frequency of light except our one color coming from the emitter.

This type of emitter/detector setup is used in a lot of sensor applications. If you have a garage that stops moving when you are in the way of it then there is a sensor involved in that garage opener. In this case an emitter is planted on the ground to the left of the garage and the detector is planted on the ground to the right of the garage. When there is no interference/blockage of the light to the detector the garage opener will operate as normal. So when a person comes up to it, the person blocks the light and the detector realizes that and stops the garage door from moving. Another cool project would be to make a door sensor that rang an alarm whenever the door blocked the path of the light.

Guitar Amplifier using Op-Amp

Today I made a simple guitar amp. I based my design around the 741 op amp chip. There are a lot of ways to make a guitar amp but this one is quite easy and involves only a couple of components. First you will need a 741 op amp chip. One resistor with a value of 470Ω and a 470Ω potentiometer/rheostat. You will also need two nine volt batteries, one acting as the positive supply rail and the other acting as the negative supply rail. An op amp needs both supplies because it amplifies signals that involve positive and negative voltage signals. The last three components you will need is a quarter inch guitar jack, a guitar and a guitar chord.

I have attached the schematic for building this circuit so I will just go into the theory of our guitar amplifier. First the 470Ω resistor is used to be compared to the value of our 470Ω rheostat. We set the amplifier as a non-inverting amplifier so when we turn the rheostat the gain of the signal will increase instead of increasing negatively. A signal is generated from the guitar that is very small and must be amplified. The signal is created by a device usually being an inductor in the guitar that takes the sound signals that you strum and converts it to electricity. Once we increase the amplitude of the guitar signal we send it to a speaker. Now we have audible sound from the guitar. Turning the rheostat to the left (< resistance) lowers the gain and makes the audio cleaner while turning the rheostat to the right(> resistance) saturates the signal and creates a cool distortion sound. Have fun building this one!

AM Transmitter Design

Here is a video of me making an AM transmitter.  It doesn't work that great but I will make it better.

Enjoy the Show!

Radio Waves WOWIE!

I have always been fascinated with radio wave signals.  When I first started learning about them I thought it was magic.  How can a certain frequency carry information which can then be decoded?  Well the radio stations we listen to include AM and FM.  AM radio is different from FM in that AM radio sends its information using amplitude modification and FM sends its information using frequency modulation.  

Transmitting amplitude modulation signals involves a carrier signal that contains audible frequencies within its bandwidth.  The carrier signal only acts as a messenger while the frequencies inside that AM bandwidth contain the audible sound.  Transmitting frequency modulation signals is similar in that it has a carrier frequency but the audible sounds are decoded by phase changes in the carrier signal.  So the audible sound of an AM signal is detected by amplitude changes in the frequency while the audible sound of an FM signal is detected by frequency changes of the carrier signal.  

The way a signal travels through air is an amazing concept.  Transmitters somehow manage to pulse out signals that can be detected hundreds of miles away.  How people do this depends on the intensity of power of that transmitter.  Transmitters need a lot of power output so the signal can be detected within a certain radius.  Air is a horrible conductor so the waves transmitting through the air really need to be pushed to be detectable by radios within the area.  That is why power is so crucial and to be more specific: power is the voltage multiplied by the current of that signal.  So that's how radio works, ain't it cool?