AC Dimmer Board Version 0.1

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Revision as of 19:41, 1 January 2012 by Isaac (Talk) (With fully assembled and working box)

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The original version was used with success during Rush 2011, despite several design flaws that needed to be corrected before the devices were functional. At least 35 strands, if not more were controlled by two DMX boxes, receiving different frequency sine waves from a python program.

The design was conceived over the summer of 2011, about six weeks before Rush. In order to get the circuit boards on time, the layout was a bit rushed. The silk screen layer leaves much to be desired, not to mention the several functional errors mentioned below.

Known Issues

  1. Ground and VCC were reversed for one input to the PIC. This was fixed by cutting some traces. One set of power supply pins seemed to work.
  2. INT0 (the first external interrupt pin) did not seem to function (possibly do to problem 1). This was fixed by cutting a trace and wiring it to INT1
  3. Two outputs to channels 3 and 4 were not working, so as above, rerouted to different output pins
  4. A lack of terminating resistor made communication difficult at times
  5. The SHDN (Shutdown) pin on the 485 transceiver was left floating, making for unreliable communication.
  6. The traces to the Triacs are small, and the Triacs or not heat sinked, limiting the current handling ability of the board.

Usage and Documentation

This Device is not recommend for usage. It has many problems that are a pain to resolve.

With fully assembled and working box

Software Installation


Untested. There is a possibility the stock FTDI driver will not operate at 250Kbps, and needs patch. Google is your friend.



Python Support for Any OS

This section has not been verified!

  • Install python 2.6 or python 2.7
  • Install libFTDI
  • Install PyUSB or maybe python-ftdi for ubuntu
  • Download the sketchy jelle library (I don't even know where the file is, probably hbf)

Hardware Setup

  • Connect the USB to DMX dongle to your computer, which should appear as a virtual serial port. oa* Connected an RJ-45 from the dongle to the box
  • Connect a few resistive loads to the box,
  • plug in the power with a standard (IEC C13) computer power cable


  1. Open QLC, click Manager > Outputs
  2. Click the pencil to edit the outputs
  3. Expand Enttec DMX USB Output
  4. Select the correct USB COM port (might require trial and error)
  5. Return to the main program window, and click on the stage light icon to open the fixture editor
  6. Click the plus icon, and add a generic fixture with 6 channels, or generic fixtures with 1 channel. The start address should be written on the box. The box will respond to the start address and the next 5 addresses.
  7. If you created a one channel fixture, repeat step 6 five more times.
  8. In Fixture Manager window, click on the fixture you want to control, and adjust the dimmes in the Console tab


  • Ensure the ftdi device is showing up properly. For version 0.1 Devices, ensure both JP1 and TXD jumpers are enabled
  • Ensure the green led is blinking rapidly (looks almsot solid green). This will happen if the device is properly configured in QLC
  • Ensure cables are good. For long runs, a terminating resistor must be connected across the data pins (Pins 1 and 2 on a RJ-45)
  • * A terminator that can be plugged inline should be available as well
  • * MAC. You're on your own. I have not had success. I think the FTDI driver is wonky. Virtualizing a linux box works.

With a unsoldered PCB

RJ-45 pinout

  1. Data 1+
  2. Data 1-
  3. Data 2+
  4. Not Assigned
  5. Not Assigned
  6. Data 2-
  7. Signal Common (0 V) for Data 1
  8. Signal Common (0 V) for Data 2