Rajendra Bhatta writes:
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 interesting 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. The following project board is designed for fast and easy development of standalone applications using PIC12F microcontrollers. It features on-board regulated +5V power supply, header connectors to access I/O pins, ICSP header for programming, a reset circuit, and small prototyping area for placing additional components.
PIC12F microcontroller project board - [Link]
I designed this controller for my Crystalite Sparrow 48V electric bicycle hub motor. The core function of a DC motor controller is to periodically read the throttle setting and adjust the current being supplied to the motor. It does this with a technique called pulse-width modulation or PWM (more on this later). Other functions of the controller include: 1) low-voltage cutoff .. monitor the battery voltage and shut down the motor if the battery voltage is too low .. this protects the battery from over-discharge. 2) over-temperature cutoff .. monitor the temperature of the FET power transistors and shut down the motor if they become too hot .. this protects the FET power transistors. 3) over-current cutoff .. reduce the current to the motor if too much current is being supplied .. this protects both the motor and the the FET power transistors. 4) brake cutoff .. shut down the motor when the brake is applied .. this is a safety feature .. if the user applies brake and throttle, the brakes win.
DC Motor Controller for Electric Bicycle - [Link]
Giorgos Lazaridis writes:
Some time ago i published a theory page regarding the LED driving and controlling methods. These methods were all linear regulators, very simple to make but very inefficient -in terms of power consumption- for high current applications. The idea was to use this theory page as an entrance level for the SMPS LED drivers.
The first SMPS (Switching Mode Power Supply) LED driver that i made is a Buck-Regulating LED Driver using a chip from Allegro Microsystems, the A6210. I was provided some samples from Farnell for testing and prototyping, along with some other cool staff. Do not forget to pay a visit to Farnell on-line store and Element14 website.
The A6210 can drive up to 3A load with constant current, with switching frequencies up to 2 MHz and supply voltage from 9 to 46 volts. It has additionally an optional PWM input to control the brightness of the LED. The sense voltage is limited to 0.18 volts for higher efficiency, since the power dissipation on this sense resistor is minimal. I will be using a 10-12V 1A 10 Watt LED, powered from 24 VDC supply.
High Efficiency High Current LED Buck Driver using the A6210 - [Link]
Giorgos Lazaridis writes:
The idea for this project came from Viktor’s site, a guy that has some interesting projects in his DIY subdirectory. He cloned a HDD spindicator with 10 LEDs driven from a 4017 chip. I liked the idea but the implementation was kinda… sterilized. So, i decided to make one for my PC, but spice it up with PWM control…
HDD LED Spindicator - [Link]
This is the fraAngelico synth by Standuino. He writes – [via]
FraAngelico 8-bit PWM digital synth is unique by the means of its sound generation. It does not use any D/A convertor but the sound is generated by just one digital output pin using Pulse With Modulation which means that by fast changing of different lenghts of pulses we can make different output voltages. Resolution of this technique to achieve different voltage levels is 8-bit but in the true essence the output form the synth is just 1-bit because the output pin does jus 1 or 0 which makes distinctive digital character to its sound.
Although this puristic and minimalistic approach to sound generation, FraAngelico is able to make wide range of different sound colours from powerfull bass to glitchy noises as well as complex rhithmic structures.
This unprocessed raw digital output can be also synchronised with any MIDI device through its MIDI input. To connect standart midi cable use the Standuino MIDI conector (coming very soon) or see tutorial how to connect more standuino devices to you soundcard (coming soon).
fraAngelico Synthesizer by Standuino - [Link]
This simple circuit that converts a 5V PWM signal into a variable precision reference voltage with a rang of -2.5V to +2.5V. Many designs, like a digitally controlled power supply, programmable dummy load, etc, require a Digital to Analog Converter to supply a stable reference votlage. [via]
The circuit described here uses the ubiquitous LM431 shunt regulator to implement a second-order Sallen-Key low pass filter together with a level shifter (see the figure). Compared to the traditional approach, it provides a far sharper roll-off along with a low-impedance output, bipolar output. It will produce a –2.5- to +2.5-V output with a 0- to 5-V PWM signal input. The value of Vout is equal to (5 V × dc) – 2.5 V, where dc is the PWM duty from 0.0 to 1.0 (0% to 100%)
Digitally adjustable precision reference driven via PWM - [Link]
Derek Wolfe writes:
This circuit provides a pulse width modulation (PWM) signal for varying the duty cycle of a load from 1-99% using a potentiometer. This is a useful way to control motor speed, LED brightness, etc.
PWM Power Supply - [Link]
LEDs don’t dim well using a an adjustable resistor, instead a pulse-width modulator is usually used to blink them rapidly giving the appearance of less light. Giovanni brings the analog charm back to LED dimming by controlling brightness via an adjustment knob (machine translation). This dimmer reads the value of an adjustable trimmer resistor with an analog to digital converter, and adjusts a the PWM output accordingly.
LED dimmer using an analog knob - [Link]
The SM72441 is a programmable MPPT controller capable of controlling four PWM gate drive signals for a 4-switch buck-boost converter. Along with SM72295 (Photovoltaic Full Bridge Driver) it creates a solution for an MPPT configured DC-DC converter with efficiencies up to 98.5%. Integrated into the chip is an 8-channel, 12 bit A/D converter used to sense input and output voltage and current, as well as board configuration. Externally programmable values include maximum output voltage and current as well as different settings on slew rate, and soft-start.
Programmable Maximum Power Point Tracking Controller for Photovoltaic Solar Panels - [Link]
Giorgos Lazaridis writes:
I decided to write this quick tutorial for two reasons: First because there are many people who would like to know more about driving and controlling LED lights, and second because i was provided an excellent LED driver chip from Farnell for test, and i wanted to put it under the microscope. So i will place this chip against some other LED drivers to see how good it is.
The chip that I’m talking about is the A6210 from Allegro Microsystems. It is a Buck-Regulating LED Driver able to drive up to 3A load with constant current, with switching frequencies up to 2 MHz and supply voltage from 9 to 46 volts. It has an optional PWM input to control the brightness of the LED. The sense voltage is down to 0.18 volts for higher efficiency.
LED driving and controlling methods - [Link]