Power Supply.
The illuminator is powered by an external DC power pack, or wall type transformer at a voltage of
24 volts DC, and a current of 350 milliamperes minimum. Suitable power sources are available
with approvals from UL and other electrical safety agencies, and in several input voltage ranges.
Power is applied to the illuminator unit through the 2.1 millimeter center positive DC plug J1 on the
rear panel of the unit. Power applied to unit passes through a self resetting current limiter, a
polarity protection diode, and a transient surge absorber before it is applied to the 5 volt regulator
IC Q3, which reduces the input voltage to the 5 volt level required by the microprocessor and other
logic circuitry. The higher unregulated voltage from the external power supply is applied to the
power / sync indicator LED, and to the LED array, as the extra voltage is needed to drive the series
connected ultraviolet LED’s used in the array. A separate 5 volt DC to DC converter is used to
power the DMX input section. This separate power supply allows the electrical isolation of the
DMX input and output lines from the remaining circuits in the unit.
Microcontroller
The illuminator is based on an Atmel ATMEGA8 microcontroller U2, which operates all critical
illuminator functions. The microcontroller uses an external 16 megahertz clock oscillator X1 for
timing control, and is internally protected against transient voltage conditions. The processor
operates from permanent firmware EPROM programming which controls all functions of the
illuminator. This programming is performed during manufacturing, and may not be re-written by
the user. The microcontroller has three 8 bit input / output ports, which may be programmed as
needed for each particular application. These ports are commonly identified by letter designations,
B, C, and D. In the BL-48 illuminator, the B port is used output data to the LED driver circuitry,
and for device programming, the C port is used for device programming and to read DMX address
settings, and the D port is to read address and mode settings, and for DMX input and sync
indication.
DMX Interface Circuits
The DMX data stream is applied to the BL-48 unit on the 5 pin male XLR connector J2, and passed
directly through to the 5 pin female XLR connector J3. DMX data is buffered by the IC U5, and the
opto-isolator OP1 before it is applied to the RXD terminal of the microcontroller on pin 30 (PD0).
The microcontroller processes the incoming DMX data, and indicates proper data reception by
outputting a sync indication on pin 11 (PD7) to the LED driver Q1 and the power / sync indicator
LED
Address / Mode Selection Circuit
The three DMX address switches S1,2 and 3 are connected directly to microcontroller inputs on
pins 23 through 28, (PC0-5), on pins 31,32, 1, and 2 (PD1-4), and on pins 19 and 22 (ADC6,7).
These pins to provide DMX address information to the microcontroller. Other inputs on pins 9 and
10 (PD5,6) are used to select the general operating mode of the unit. The remaining input
connections on pins 14-17, and 29 (PB2-5, PC6) are used for device programming.
