bilda Hardware

What does bilda stand for? What is bilda?

bilda, the name of this project, is a contraction of "billiger D/A-Wandler mit ISP kompatiblem Ausgang", which means "cheap D/A-Converter with ISP compatible output" in English.

The task of this hardware is to generate the neccessary voltage signals to control a laser projector under computer control.
The laser projector uses these signals to set the deflection angle, color and brightness of the laser beam accordingly. Through fast variation of these signals it is possible to display graphics or beam effects. Because laser projectors are vector oriented a set of deflection and color data is also called a point. Laser projectors are usually supplied with points at a constant rate, that means the time interval between two consecutive points should always be equal.

bilda can output up tp 50.000 points per second with constant timing. The resolution of the X- and Y- channels is 8 Bit, also that of the three color channel.
The analog output signals conform to to the Standard Projector specification of the International Laser Display Association. This makes bilda compatible with a wide range of laser projectors.

The communication on the computer side occurs over the USB Port. The special transfer mechanisms used guarantee that the time between two points is always constant and is never disturbed, like it happens to other solutions that are based on the LPT port or ISA bus.

The bilda project does not only consist of hardware. A firmware for the USB-Microcontroller, which is doing its duty on the bilda board, and a Linux kernel module are neccessary for bilda to function. This Software is developed here as an open source project.

bilda was designed to be home-brew hardware for hobbyists and Laserfreaks. The circuit fits on a single-sided euro format(100mmx160mm) pcb. The parts cost about 50 Euro.

Please also see the Section about Laser Safety.

Hardware Plans

The .brd/.sch files can be opened using the freeware version of Cadsoft Eagle, a Schematic and Layout Editor for Linux and Windows.
bilda Schematic (.png)
bilda Schematic (.sch)
bilda Board (.brd)
bilda Board (.png)
bilda Layout (.ps)
bilda Layout (.pdf)

Parts List

Power Supply

bilda needs a DC supply of +5V, +12V and -12V for operation. The cheapest source of these voltages is probably an old AT(X) power supply.
bilda uses a Molex plug for power supply which is wired different from the standard. To use bilda with an AT(X) power supply the ground wire (black) next to the +12V wire(yellow) has to be exchanged with a -12V connection. -12V can be found on the motherboard connector, the wire is usually blue.
If bilda is supplied from an unmodified Molex plug, which connects bildas -12V input to ground, nothing will break, but all outputs will stay at 0V output voltage.

Pictures of the Prototype:

bilda at work:

The following pictures were all recorded using bilda.
The Projector used consists of a green und blue 100mW DPSS Laser, a red 100mW Laser Diode, a four channel A&A PCAOM and CT6210 Galvos with HB Apollo SuperMicro Amp.

Notice the smooth color gradient; bilda can generate 16.7 million colors.	A Dolphin. You can download this ILDA file from LaserFX.
	The ILDA Test Pattern. bildas 8-Bit Quantization harms the text rendition a little.
Even Raster-Scanning is possible.

These three pictures are impressions of the Explode Beamshow for HE_LaserscanII. Get it here.