PCB Layout I have provided the PCB layouts in Gerber, Postscript and PDF formats. Both the zip and gzip archives contain all the layouts. PCB_dmx_relay.tgz (112KB) PCB_dmx_relay.zip (140KB) Assembling the PCB You should familierise yourself with the PCB and the positions of the components. Get the components and make sure you know which one is which, and where it goes. Removing components is not all that easy and its much better to spend some time getting them right in the first place. You will need an iron with a small tip as some of the tracks are very close together. Its also a good idea to make sure you iron is fairly hot (mine is set to 600 °F / 340 °C), that way you can be a lot quicker, thus having less potential to damage any components.

Whilst nearly all of the components will be fitted on the top of the PCB, there is the possibility that C3 will need to be mounted on the underside. This will depend on wether you plan on using a socket to mount the microprocessor (IC1) in. My recommendation is that you do use a socket as this not only facilitates swapping it out if necessary, but also means you are not soldering directly onto the microprocessor so are a lot less likely to damage it.

Not all the components are marked on the PCB silk. To the left of IC2 and IC3 you will find a pair of unmarked holes, these are for C1 & C2. C3 fits in the middle of IC1, and may need to be mounted on the underside of the PCB. The SIL bussed resistors R13 & R14 fit immediatly to the left of IC1, and then the DIP switches or jumpers fit to thier left.

Having sorted out your components its time to solder them onto the PCB. I always start with the smallest components first, moving up through the sizes till I come to the largest. This means that when you turn the PCB over to solder the part can be held more securely against your workbench, as opposed to flapping around.

The order I reccomend is :-

1. Resistors
2. Diodes (not LEDs)
3. Capacitors (Remember to check if C1 will be underneath)
4. XTAL
5. IC's
6. Transistors
7. LEDs
8. Connectors
9. Relays
10. DIP Switches.

Connections and testing You will need to connect 0v and 5v to CN7. 0v connects to pin 3 and 5v to pin 2. DMX is connected on CN8. 0v is connected to pin 1, Data -ve to pin 2 and Data +ve to pin 3 Set the DMX start address to at least 1, connect it to your lighting desk, and power up the board. The LED next to the CN8 shoulds light. This shows that DMX data is being received by the interface. Bring the level on the start address channel up to full and RL1 and its associated LED should switch on.