February 28th, 2009

Head mount display hack

Head mount display hack

Ever wondered what’s inside a head mounted spy gadget? Well, now you have the answer, there was somebody curios enough to take apart a robot toy which had a camera and eye piece, considering the size, isn’t a James Bond type of gadget so don’t expect to find any nanotechnology inside, but you can see how the LCD displays work. Even your LCD monitor uses the same solutions, only in bigger.

Head mount display hack inside

This post is for people curios enough to dismount  similar electronics, my advice : don’t, you won’t find any components inside which you can use, or there are hard to remove from the pcb and if you damage the flexible pcb or any other part, you probably can’t repair it

Head mount display hack: [Link]

February 15th, 2009

IR light dimmer

IR light dimmer

This can be considered an old project, and yes you can buy the commercial version quite cheap too, but in case you want to build one, this is a working project. The source code isn’t made public, but since it was written in assembler language probably wouldn’t be any use at all.

It is a compact and clever dimmer, with capacitive power supply and a small PIC micro controller, it can be mounted in very small space. The learning process is straight forward and explained step by step. It has also a 110V/60Hz version of the hardware and complied firmware.

Keep in mind that this device uses the potentially lethal mains voltage, care should be taken when testing and mounting, use good quality isolation and disconnect from mains when handling.  When powered up, please don’t touch the triac to see if it gets hot because you will get zapped, this is a basic mistake, and maybe the most common among hobbyists.

IR light dimmer: [via] [Link]

February 13th, 2009

AVR FM transmitter

AVR FM transmitter

When it’s about FM transmitters most of the people think about complicated circuits with LC oscillators, tuning problems, pcb coupling issues and the high risk of failure. You can find dozen or more schematics on the web, I personally tried a few, but without luck because I couldn’t tune in the oscillator.

The mathematical background is complicated, but well explained for those interested, the code is written is assembler which is a must since the tight timing. Beside the inductor all of the components are widely available, this must be hand made and by stretching you can fine tune the oscillator, thing which will be probably needed.

By using surface mount components the pcb size could be greatly reduced, but keep in mind when making the layout to reduce coupling and noise susceptibility.

Make sure that you don’t disturb any local frequencies, or somebodies privacy with it.

AVR FM transmitter: [via] [Link]

February 12th, 2009

Video overlay with AVR

Video overlay with AVR

If you have a camera and want to add additional data in real time to the captured image, you need to overlay your text on the original picture, most of the cases the overlay image is a low resolution text, at first I thought this would be very complicated, but after I found this project I had to change my mind. By using only the ATmega8 and LM1881 the author can overlay any text on the S-video signal.

Video overlay with AVR

Since high frequencies are involved the proper ground is needed to avoid noise problems, since the breadboard isn’t suited for frequencies above 10kHz, the author used a thin aluminum  foil as shield, if you make a pcb keep in mind that the LM1881 is very sensitive.

The project doesn’t need any expensive components, and work even on a breadboard, the firmware is written in C and is available for download, you can easily modify it to display your custom messages. Since most of the video cards in PC’s have output in S-video format too, this device has a great potential.

Video overlay with AVR: [via] [Link]

February 7th, 2009

Random twinkling LED heart

Random twinkling LED heart

If you want to impress somebody on Valentine’s day this is a great opportunity, make a DIY led heart, the project comes along with all the source code schematics and even a tutorial to explain the software.

Beside the obvious, lets take a deeper look at the project, the leds are twinkling at random speed and pattern, and yes there are fading not just turning on and off, and there are 20 of them, so how do they do it? No there isn’t a large micro controller with 20 channel pwm, they emulate it in the firmware, and use random numbers to set each leds twinkle. Its worth looking at the solution since in many application, especially with leds  you will need to fade more channels than your pwm hardware can handle.

The project also comes with schematic, if you build this kit, place at least a series resistor of 100 Ohm value with PC5 pin, just in case you start to improve the software and forget that the pins can handle only 25mA.

Random twinkling LED heart: [Link]

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