About

The BlackBox case commercialised by Elbox seems to be just a mildly reverse-engineered Zalman PC case that, except from the backplate, seems to not be designed in any way specific to the Amiga 1200. One of its major flaws is the weird design decision to not provide a way to display the Amiga 1200 activity LEDs because, traditionally, the status LEDs (HDD, FDD and Power) provide crucial debugging information. In order to overcome the lack of Amiga-speficic design, the following guide illustrates how a simple LED circuit can be implemented and mounted onto the BlackBox case.

Requirements

3 LEDs - green for power, amber / orange for floppy disk activity and red for hard drive activity.
3 $220\Ohm$ resistors.
Small PCB board.
$40cm$ Dupont cables.
$2.54inch$ single row IDC pins.
Soldering equipment.

Circuit Design

Measuring the output from the Amiga 1200 status LED connectors it is observed that the voltage passed to the LEDs fluctuates with the purpose to indicate activity between $0$ and $5V$ . Knowing that LEDs are usually rated at about $20mA$ , the required resistor is deduced as:

$\begin{eqnarray*} U &=& R * I \\ R &=& \frac{U}{I} \\ &=& \frac{5V}{0.020A} \\ &=& 250\Omega \end{eqnarray*}$

For more brightness, a $220\Ohm$ resistor can be used instead. Following the schematics, the following sketch is used for the circuit:

<--- Amiga connector

GROUND *-----------------------+
                               |
       *                       |
              220      RED     |
HDD    *-----/\/\/-----(->)----+
              220      ORANGE  |
FDD    *-----/\/\/-----(->)----+
              220      GREEN   |
POWER  *-----/\/\/-----(->)----+

In order to reduce overhead and spare space, very small SMD resistors have been used for the project.

Gallery

Table of Contents

About

Requirements

Circuit Design

Gallery