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Hobby projects - Simple electronic circuits

Computer microphones Learn how to interface electret and dynamic microphones to the standard computer sound card. Metal detectors Theory of operation and schematics of the most common metal detectors used today: Very Low Frequency (VLF), Pulse Induction (PI) and Beat-Frequency Oscillator (BFO). Wireless microphone The wireless microphone transmitter can be built in an afternoon with simple, affordable and widely available parts.

ABCelectronique, portail de l'électronique Handbook of hardware pinouts, cables schemes and connectors layouts Mike's Electric Stuff Réalisations - Alim. led Electronique > Réalisations > Alimentations > Alimentation d'une LED Dernière mise à jour : 06/03/2016 Présentation Les lignes qui suivent décrivent comment utiliser une LED de façon isolée ou en groupe, avec des tensions alternatives ou continues. Pour plus de renseignements concernant ce composant, merci de vous reporter à la page Théorie - LED. Bases - Alimentation en basse tension continue Une LED, si on l'alimente directement et sans autre forme de procès à une source de tension continue (pile 9 V neuve par exemple) ou à une source de tension alternative (secondaire d'un transformateur 220V / 9V par exemple), a 99% de chances de griller. Sur le schéma qui précède, la valeur de la résistance R1 est donnée à titre indicatif, la tension V n'étant pas spécifiée. La LED utilisée pour les deux expériences qui suivent est une LED verte fonctionnant de façon nominale avec une tension de 2,2 V et un courant de 20 mA. Valeurs typiques de tensions et courants pour quelques LED Remarques Oulà !

Electronic Circuits on Circuit Exchange International (CXI) Motors and Microcontrollers 101 Electric motors are a key way of converting electrical power (voltage and current) into mechanical power (torque and speed), and because electric motors are simple and reliable machines, they can be found all over, in many different shapes and sizes. Just considering a normal (gasoline-powered) car, there are a great number of electric motors: the powerful starter motor and alternatoralternating windshield wiper motorsintermittent-use power windows and door locksthe blower fan that moves hot and cold air into the cabinthe tiny motors inside the CD player And I'm sure you can think of others. While a full analysis would have to look simultaneously at the motor and the attached mechanical system, in this video tutorial we're just going to address the electrical side of the system. Here are some photos and drawings related to the video (click to enlarge): Our final motor control circuit looks like this: Spinning the motor makes a voltage. Go give them a try! Maximum forward current.

Bipolar junction transistors as switches : Worksheet Question 1: Solid-state switching circuits usually keep their constituent transistors in one of two modes: cutoff or saturation. Explain what each of these terms means. "Cutoff" refers to that condition where a transistor is not conducting any collector current (it is fully off). "Saturation" means that condition where a transistor is conducting maximum collector current (fully on). Notes: In all fairness, not all transistor switching circuits operate between these two extreme states. Question 2: Explain the function of this light-switching circuit, tracing the directions of all currents when the switch closes: Notes: Ask your students to explain what possible purpose such a circuit could perform. Question 3: Trace the directions of all currents in this circuit, and determine which current is larger: the current through resistor R1 or the current through resistor R2, assuming equal resistor values. I'll let you determine the directions of all currents in this circuit! Question 4: Question 5:

b e a . s t [an error occurred while processing this directive] Magnetic Levitation using Hall effect Sensor Feedback, and Matched resonant wireless power transfer This work was completed initially for a final project for Joe Paradiso's class MAS.836 - Sensor systems for Interactive Environments, taken Spring 2oo5. Click to watch the following movies:Magnet Levitation Movie [100 megs], or in Small form. Motivation: My goal is to build the subsystems to be able to magnetically [stably] levitate a lightbulb that is powered at all times through the air using a matched resonant air-core transformer. In order to levitate a lightbulb, there are three main systems that needed to be explored and techniques that needed to be developed. Implementation: The general goal setup is as shown to the right. Around the electromagnet sits another coil, the primary of an air-core resonant transformer; the secondary winding sits near the neodymium magnets inside the light bulb. Hall Effect Sensing: One problem remains.

Tutorials The most fun you can have (after blinking LEDs) is using sensors to detect whats going on in the world and act on that information. However, all sensors have their own methods of interfacing. That can make them a real pain to work with: some need pull-up resistors, some need certain power supplies, some use lots of power, some don't. Since there aren't that many different sensors that people tend to want to use I have collected the most common sensors with code examples and wiring diagrams. Tutorials include: Force sensitive resistor - Used to detect physical pressure such as pinching, squeezing, pushing, brushing. Photocells - Used to detect light/dark, breakbeams, simple object detection.

Arduino and the AREF pin Learn how to measure smaller voltages with greater accuracy using your Arduino. This is chapter twenty-two of our huge Arduino tutorial series. Updated 12/12/2013 In this chapter we’ll look at how you can measure smaller voltages with greater accuracy using the analogue input pins on your Arduino or compatible board in conjunction with the AREF pin. However first we’ll do some revision to get you up to speed. Revision You may recall from the first few chapters in our tutorial series that we used the analogRead() function to measure the voltage of an electrical current from sensors and so on using one of the analogue input pins. And when we say the operating voltage – this is the voltage available to the Arduino after the power supply circuitry. This can easily be demonstrated by connecting an Arduino Uno to USB and putting a multimeter set to measure voltage across the 5V and GND pins. This is important as the accuracy of any analogRead() values will be affected by not having a true 5 V.

Lab 14: Inter-Integrated Circuit (I2C) communication I2C (Inter-Integrated Circuit) is a short distance serial interface that requires only 2 bus lines for data transfer. It was invented by Philips in 1980′s, originally to provide easy on-board communications between a CPU and various peripheral chips in a TV set. Today, it is widely used in varieties of embedded systems to connect low speed peripherals (external EEPROMs, digital sensors, LCD drivers, etc) to the main controller. In this experiment, we will cover an overview of I2C protocol, its implementation in PIC microcontrollers, and the method of connecting single and multiple devices on a common I2C bus. We will demonstrate the technique by connecting two I2C EEPROM chips (24LC512) and an I2C compatible temperature sensor (DS1631) with PIC18F2550 microcontroller. I2C devices with PICMicro Theory I2C bus has two lines: a serial data line (SDA) and a serial clock line (SCL). Start and Stop conditions Signaling for Start and Stop conditions I2C device addressing Data transfer Acknowledgment

10A H-Bridge Motor Controller - Introduction Motor control is the core heart of robotics. Without locomotion or any movement a robot is dull and lifeless. The H-bridge is a tried and true concept for DC motor control. 10A H-Bridge Test Video 10A H-Bridge Completed 10A H-Bridge PCB And All Parts 10A H-Bridge With PWM Input Purpose & Overview of this project The main goal for this tutorial is to build a 10 AMP motor controller that can control a DC motor with a digital input. Arduino’s AnalogWrite – Converting PWM to a Voltage D-A_converter When I first started working with the Arduino platform (it was also my first experience with microcontrollers), I was a little surprised that analogWrite didn’t actually output a voltage, but a PWM (pulse-width modulated) signal. After all, the ATmega had a A-D (analog to digital) converter along with Arduino’s analogRead. PWM Primer Pulse width modulation (or PWM as it is most commonly known), is a way of encoding a voltage onto a fixed frequency carrier wave. With the need for digital communication, a new modulation technique was invented – PWM. PWM outputs (curtesy arduino.cc) For the Arduino, you write a value from 0 to 255 on a PWM pin, and the Arduino library will cause the pin to output a PWM signal whose on time is in proportion to the value written. When it comes time for us to actually write an output voltage, the 0-255 value lacks meaning. Pin Value (0-255) = 255 * (AnalogVolts / 5); Modulating a Signal Changing the Modulation Frequency Low Pass Filtering Conclusion

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