Introduction: Pro USB DMX Controller and Terminator for QLC+

Today I want to share with you how to make a professional looking USB DMX controller to use with lighting control software such as QLC+. In roughly 5 to 10 minutes and about $35 in parts and shipping.

This project may actually take less time for you to compete than it takes for your soldering irons to heat up.

It only requires three parts. An FTDI USB-RS485-WE-1800-BT cable, A female XRL connector and a 13/64" x 1/4" piece of shrink tubing.

After you complete this project you will end up with a professional looking USB-DMX interface you can be proud to show off. If you complete the DMX terminator portion also; you will have everything you need to connect to any DMX enabled fixture or a whole DMX universe. You can also make and use more than one at a time to control multiple universes.

There are other tutorials that claim you can accomplish the same outcome for around $10. But this is not completely true. They fail to mention on top of purchasing the $10 board you need in addition: wire (?), panel mount connector ($6), a project box ($10) and shipping (shipping alone was around $30) for a total of about $65 not $10. Then the majority of the time the chips have to be hacked because the board manufacture changes chipsets or board design. In the end you end up with something pieced together and only works part of the time if you can even get it to work.

Im not claiming this project is cheaper depending on vendor and your location, shipping and tax may differ slightly. Im just saying this works, its clean, and parts can be purchased directly from the same manufacture and function as reliabley as a $150 name brand USB DMX controller.

Step 1: Make Sure We Have Everything We Need.

Parts and Tool list.
1) FTDI USB-RS485-WE-1800-BT cable

1) Female XRL connector

1) 13/64" x 1/4" piece of shrink tubing

1) Soldering iron.

1) Wire cutters

1) scissors

Other Links

Element 14 USB-RS485-WE-1800-BT

Element 14 XLR

Digi-Key USB-RS485-WE-1800-BT

Digi-Key XLR

Disclaimer: This is a do at your own risk. I hold no responsibility for burnt fingers, damaged equipment etc.

Step 2: Trim Red Wire

Do NOT cut the red wire all the way off.

We want to trim the red wire down to about 1/4".

If you cut the red wire flush with jacket you will likely short it out on a cup when putting XLR together. Causing damage to your DMX fixtures and your computer.

Step 3: Terminate Data

We need to terminate Data+ and Data- with 120 ohm resister as per TIA-485 standards and FTDI spec sheet.

Lucky for us there's a 120 ohm terminating resister on the PCB 120R Pin 1 (Brown Wire) and 120R Pin 2 (Green Wire)

Basically we just need to know we need to twist the green and yellow together. Then twist brown and orange together.

Step 4: +5V Isolation

We need to fold the red wire back onto jacket & secure with a piece of shrink tubing, insuring that the tip of the red wire is completely covered by the shrink tubing.

By doing this we are preventing the USB +5 volts from shorting out. If the red wire is not properly isolated it could destroy your DMX fixtures and/ or computers USB.

Step 5: Install XLR Strain Relief Boot

Step 6: Prep Female XLR

We need to tin the cups on the back of the XLR.

Step 7: Prep Cable

We need to tin the wires to insure a good solder connection to the XLR cups.

Note: Ive had a couple people ask how I got shrink tube to stay on the alligator clips without splitting.... That is not shrink tube on the alligator clips, it the outer jacket of a piece of Cat5. Cat5 jacket works good to protect wires when clamped in alligator clips. Protecting wire jacket from being nicked by the alligators serrated jaws. And slides off easily when you need to clamp connectors or boards in your alligator clips.

Step 8: XLR Pin 3 (Orange and Brown)

We need to solder the orange and brown wires to pin 3 on the back of the female XLR connector.

Step 9: XLR Pin 1 (Black)

We need to solder the black wires to pin 1 on the back of the female XLR connector.

Step 10: XLR Pin 2 (Yellow and Green)

We need to solder the yellow and green wires to pin 2 on the back of the female XLR connector.

Step 11: Install XLR Strain Relief

Step 12: Assemble XLR

Step 13: Part 2 (DMX Terminator)

Step 14: 120 Ohm Resistor

Solder a 120 ohm resistor between pins 1 and 3 on the back of a male XLR connector.

Step 15: Disassemble XLR Boot

Using a small screwdriver or something similar. Push the strain relief tension ring out of the XLR boot. Then remove the boot from the collar/ nut.

Step 16: Trim Strain Relief Tension Ring

Trim off the portion of the ring that protrudes into the boot.

Step 17: Trim Strain Relief

Trim strain relief so it flush when tension ring is push down on the strain relief.

Step 18: Test Fit

Step 19: Cap the Back

take a thin piece of plastic and cut it the same size as tension ring.

I used a plastic business card. But the top off a gallon of milk works well also if you want to color code universe ends to aid in troubleshooting.