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rookieelectronics writes:
This is my favourite project, its too simple and very interesting because it does not require any voltage source
it converts RF frequency waves from cell phone (whenever you call or send a text) to little current to flash a LED.
Actually this project is also called as LED power meter, it is used to test RF equipments. It can detect output power of our FM transmitters, by simply connecting voltmeter in the place of the load(LED) of this circuit.
Cell phone RF radiation Detector - [Link]
Detect particles and/or make a cool random number generator with this handsome Geiger counter kit. This easy-to-make pack of parts turns a simple Geiger-Muller tube (included) into a portable blink, beeping radiation detector. You can also connect an FTDI friend to the header, to get serial output for datalogging on your computer.
Geiger Counter Kit – Radiation Sensor - [Link]
IR detectors are little microchips with a photocell that are tuned to listen to infrared light. They are almost always used for remote control detection – every TV and DVD player has one of these in the front to listen for the IR signal from the clicker. Inside the remote control is a matching IR LED, which emits IR pulses to tell the TV to turn on, off or change channels. IR light is not visible to the human eye, which means it takes a little more work to test a setup.
IR detector – [Link]
Candymanproductions writes:
This is a great, simple project to make a small and robust 9V IR detector. It can be used to seek out security cameras that use infrared light to “see” or to check if your remote control is still working.
9V IR detector - [Link]
Mike Chambers writes:
Here is how it works. I have an Arduino Duemilanove with ATMega328 which has two photo-resistors connected (with a 10k pull down resistor). I set up two laser pointers to shine a laser directly onto the photo-resistor (which is enclosed within a dark box). The Arduino monitors the values returned from the light sensor, and watches for any changes that indicate that the laser bean has been broken. When both laser beams are broken, the Arduino calculates the amount of time between when each sensor was tripped. It then sends that value to the Adobe AIR based client, which is connected to the Arduino via USB / Serial port and a serial port proxy (in the case, TinkerProxy).
Arduino based speed detector with a Flash! – [Link]
1324itouch writes:
Hello everybody!!!
I have been messing around with a few components and my arduino. I figured out this project last week and just had to share it with all of you. What it is, is a laser beam hitting a photo cell. The arduino reads the photo cell and when it detects the voltage level is below a certain amount, the beam must be broken while sounding an alarm. The alarm stays on until you punch in the code you have set up to the keypad in. Once the correct code is typed in, the arduino turns of the buzzer and gives you 15 seconds ( or what ever you set the delay time to) to reset the laser beam. You are able to change the code if you like. The steps are very easy to follow and i hope everyone makes one!!!
Arduino laser detector with keypad – [Link]
Bill takes apart a smoke detector and shows how it uses a radioactive source to generate a tiny current which is disrupted when smoke flows through the sensor. He describes how a special transistor called a MOSFET can be used to detect the tiny current changes. [via]
Bill Hammack vs The Smoke Detector: “Engineering At Its Best” – [Link]
electrobob.com writes:
A certain knock at the door may tell you if the person behind it is the one expected or just somebody else. Each knock on the door itself cannot tell you too much, it can be lighter or stronger and that’s all about it, there’s no information on pitch here. But a certain sequence of knocks can be an actual secret code. The secret knock is encoded in the actual timings of the knocks, the time between each knock creating a distinguished pattern.
Secret knock detector with 555 – [Link]
This project is a simple bat detector that allows you to hear any ultrasonic sound. It digital scales the ultrasonic sound down to human hearing range (20 Hz to 20 kHz). The bat emits ultrasonic range from 9 kHz up to 200 kHz! Therefore, to enable us to hear the frequency, you should create a bat detector device that can analyze up to 20 kHz. To achieve that, digital frequency division is used.
The Ultrasonic Bat Detector – [Link]
This project is an IR beam break detector that has a range of 10m. After publishing IR Short Distance Beam Cut Detector Giorgos Lazaridis received requests for a version that will have extended range so he build the circuit on the link below. The transmitter is based on 556 timer IC that has two 555 timers inside and an high power IR led. The receiver is based on TSOP1838 IR receiver chip, a 555 timer IC and a 4017 decade counter. Check schematics and construction details on the link below.
Long Range (10m) IR Beam Break Detector – [Link]
