pwm

140 Articles

Sound Card Driven Servo Motor

May 26, 2010 by 14 Comments

[youtube=http://www.youtube.com/watch?v=1LG2Ecsk13Q]

[Darrell] is using a sound card to drive this servo motor. The motor draws power from a cellphone battery with the control signal coming from one of the audio channels. It’s not too surprising that this works since the motor just needs a PWM signal to operate and that’s what is used to create the different frequencies of sound on electronic speakers. We’re not sure what [Darrell’s] got planned for this system but he mentions that two servos can be used, one on each audio channel. If you’re not using your sound card this would be a way to stop using the Arduino for that mail checker and just use a little flag attached to a servo. When mail comes in the appropriately engineered sound raises the flag.

USB VU-meter

April 22, 2010 by 14 Comments

[youtube http://www.youtube.com/watch?v=jsg24MGNpRc&feature=player_embedded%5D

WaitingForFriday’s [Simon Inns] is quite possibly the USB interface and PIC master. This week he let us know about his VU-meter repurposed as a computer performance monitor using a PIC18F2550 and his open source USB Generic HID communication class. With PWM the meter’s needles and RGB LED can be accurately set and even dampened for CPU usage, network usage, HDD utilization, and even memory usage. Oddly enough, in his software we didn’t find the ability to use the device as a VU-meter – go figure.

PWM Fan Controller For External Hard Drive

April 14, 2010 by 27 Comments

[Alan] noticed that his external hard drive was getting quite hot to the touch after a few hours. He says that it was probably designed to handle the heat sufficiently, he thought it would be fun to beef it up. He’s using a pic 12f675 microcontroller as the brain and an LM35 temperature sensor. The Fan speed is varried in 8 steps from 35 degrees C to 45 degrees C.

Autonomous Bassline Generator

December 18, 2009 by 16 Comments

[youtube=http://www.youtube.com/watch?v=dcqpxd0O6Mw]

We’ve been watching this project ever since [Dann] emailed us about the first prototype back in September. This bassline generator has a lot of functions we like, such as an adjustable melody seed, light-sensitive controls, and device interactivity. Line up a row of them and they’ll sync up the beat, building layers of sound on top of each other (see the first video after the break).

The system is built around an ATtiny84, putting its pulse width modulation channels to work for sound generation. [Dann] has some kits available but he’s also posted everything – the schematics, PCB layout, and code – if you want to throw one together on a breadboard.

Continue reading “Autonomous Bassline Generator” →

Software Pulse Width Modulation

September 17, 2009 by 11 Comments

daqq_pwm_schematic

Pulse Width Modulation is a topic that tends to give a lot of beginners trouble. [Daqq], whose nixie plasma ball we covered a few days ago, has a simple but effective PWM project that you should take a look at. The circuit used 9 LEDs clustered together into 3 sets of RGB modules and connected them to an AVR ATtiny2313 through some current limiting resistors. Most of the time the PWM function of the AVR’s timers would be used to generate the signal but this application calls for 9 signals which is more than can be produced by this chip. The workaround is to generate the signals using software PWM. Continue reading “Software Pulse Width Modulation” →

AVR Boost Converter

July 7, 2009 by 19 Comments

avrboost

Over at SpriteMods, [sprite_tm] realized that a microcontroller could be used as a boost converter to power itself. A boost converter steps up voltage from a battery by switching the output of a coil. First, it is tied to ground so a magnetic field can build up in the coil. It is then released as a higher voltage than the input. Normally dedicated chips do this at an incredibly high frequency, but the PWM signal from an AVR works well enough. This can be used in low-power situations where space is an issue.

[via EMSL]