Marios Andreopoulos writes:
A few days ago I wrote a blog post about Arduino and EMI. By using fast PWM and a plain breadboard wire, I was able to detect electromagnetic interference using a usb TV tuner, with its antenna near my circuit. Not only that, but by manipulating duty cycle to create a primitive form of amplitude modulation, I was able to transfer through EMI a very simple audible signal (few notes of one of the most famous riffs) in many frequencies and up to 1.76GHz
Fast PWM and Electromagnetic Interference - [Link]
LED drivers are electrical devices that regulate the power of LEDs. What makes them different from conventional power supplies is their ability to respond to the ever-changing need of LEDs in a circuit by supplying a constant amount of power as electrical properties change with temperature.
The PCA9622 is an I2C-bus controlled 16-bit LED driver optimized for voltage switch dimming and blinking 100 mA Red/Green/Blue/Amber (RGBA) LEDs. Each LED output has its own 8-bit resolution (256 steps) fixed frequency individual PWM controller that operates at 97 kHz with a duty cycle that is adjustable from 0 % to 99.6 % to allow the LED to be set to a specific brightness value. An additional 8-bit resolution (256 steps) group PWM controller has a fixed frequency of 190 Hz and an adjustable frequency between 24 Hz to once every 10.73 seconds with a duty cycle that is adjustable from 0 % to 99.6 % that is used to either dim or blink all LEDs with the same value.
These LED drivers are based on system-centric, mixed-signal LED driver technology for backlighting and solid-state lighting (SSL) applications. This broad-based and rapidly growing market includes LCD TVs, PC monitors, specialty panels (industrial, military, medical, avionics, etc.) and general illumination for the commercial, residential, industrial and government market segments. LED drivers utilize a proprietary and patented combination of analog and digital circuit techniques and power control schemes.
- PCA9622 I2C-bus controlled 16-bit LED driver
- 2C-BUS/SMBus MASTER
- Resistor 10kΩ ( 27 units)
- LED (88 units)
- Voltage Source 40Vdc
- Voltage Source 5Vdc
I2C Bus Controlled LED Drivers for backlighting and SSL applications – [Link]
“Click And See “ is a system supporting the search of electronic components. The idea came during yesterday’s shopping in one of the electronics stores , cabinets with electronic components fill the entire wall. When buying several different components , the seller needs time to find them first in your computer , then in the appropriate bins , and the queue of customers getting longer … To facilitate this, I designed a simple , wireless and easy to expand the system to highlight the drawer of the element that want to buy .
more info here: CLICK_AND_SEE_ENG
Click and See – find electronics parts with a click - [Link]
Nick Leijenhorst build a 555 PWM circuit to dim his room LED lighting. He writes:
I wanted to dim my room LED lighting with a potentiometer, and decided on creating a solution from scratch to make it more fun and educative. I decided to go with the fairly well-known 555 PWM circuit. To decrease size and for learning purposes I decided on using surface-mount components for the first time. The reason I wanted to make this 555 PWM circuit is actually just to see if I could solder SMD components on home-etched PCB’s, and to see how hard it actually is.
Surface-mount 555 PWM circuit - [Link]
by Aruna Rubasinghe:
The LM317T from National Semiconductor is a popular adjustable-voltage regulator that provides output voltages of 1.25 to 37V with maximum 1.5A current. You can adjust the output voltage with a potentiometer. The circuit in Figure 1 replaces the potentiometer with an analog voltage that you can control from a PWM (pulse-width-modulation) signal. You control this signal with a microcontroller or any other digital circuit. You can use the same microcontroller to dynamically monitor the output and adjust the LM317T.
Control an LM317T with a PWM signal - [Link]
Embedded Lab’s new development board for PIC12F series microcontrollers:
The 12F series of PIC microcontrollers are handy little 8-pin devices designed for small embedded applications that do not require too many I/O resources, and where small size is advantageous. These applications include a wide range of everyday products such as hair dryers, electric toothbrushes, rice cookers, vacuum cleaners, coffee makers, and blenders. Despite their small size, the PIC12F series microcontrollers offer many advanced features including wide operating voltage, internal programmable oscillator, 4 channels of 10-bit ADC, on-board EEPROM memory, on-chip voltage reference, multiple communication peripherals (UART, SPI, and I2C), PWM, and more. Today we are introducing a new development board (rapidPIC-08 V1.0) for easy and rapid prototyping of standalone applications using PIC12F microcontrollers.
Rapid development board for PIC12F series microcontrollers - [Link]
Davide Gironi writes:
This library is an update of the software PWM driver you can find here.
This update implements also progressive start / stop features. So, with this one, you can drive up to 4 motors independently controlling: speed, direction, slow start / stop
Driving a DC motor using software PWM with AVR ATmega - [Link]
The MAX31740 is a sophisticated, yet easy-to-use fan-speed controller. It monitors the temperature of an external NTC thermistor and generates a PWM signal that can be used to control the speed of a 2-, 3-, or 4-wire fan. The fan control characteristics are set using external resistors, thereby eliminating the need for an external microcontroller. Controllable characteristics include the starting temperature for fan control, PWM frequency, fan speed at low temperatures, and slope of the temperature-duty-cycle transfer function.
MAX31740 – Ultra-Simple Fan-Speed Controller - [Link]
jimk3038 @ instructables.com writes:
This instructable fully describes building a PWM driver to control four LEDs from one small Microchip 12F609 board. The original design was called the “Kemper LED Lamp” and I sold a few lamps to several brave folks through my web site. However, I’ve come to discover selling small quantities to a few folks is a major pain in the backside. Hand soldering these together and then selling them at $4 bucks each is no way to make money.
Open Source Microchip LED / PWM Driver Project - [Link]