Projector
A few years ago there was quite an active scene of DIY projector builders, using stripped down LCDs, metal hallide bulbs and fresnel lenses to produce an image. At the time XGA resolution (1024x768) projectors were quite expensive, so the economics of building your own were quite compelling - if you counted your labour as free of course. I decided to have a go and you can see the results of my efforts below. The projector can produce almost-HD images about 80” in size.
The projector was modelled in SolidWorks, and most of the parts were CNC machined (using a CNC router I also designed and built). A PIC16877 based control system drives four fans, a stepper motor to control focus, senses temperature at two locations via thermocouples, and interfaces with the user via a two line red-backlit LCD and a Blackberry style trackball. It keeps an eye on the temperature and shuts the bulb down if anything overheats. Fan speed is regulated according to temperature. When the power switch is flicked off it saves the focus position, retracts the lens, and keeps the fans running until everything’s at a safe temperature before shutting down. It restores the lens to its previous position on power up.
The projector was modelled in SolidWorks, and most of the parts were CNC machined (using a CNC router I also designed and built). A PIC16877 based control system drives four fans, a stepper motor to control focus, senses temperature at two locations via thermocouples, and interfaces with the user via a two line red-backlit LCD and a Blackberry style trackball. It keeps an eye on the temperature and shuts the bulb down if anything overheats. Fan speed is regulated according to temperature. When the power switch is flicked off it saves the focus position, retracts the lens, and keeps the fans running until everything’s at a safe temperature before shutting down. It restores the lens to its previous position on power up.