4-Way P-DMX Splitter (Non Isolated)

[David_AVD]

Here's the 4 way P-DMX splitter design that was discussed in chat over the last couple of days.



One MAX485 is for the input, while each of the other MAX485 chips feeds two outputs. This is ok as this is an implementation of a mid-span driver.

The input is also P-DMX and has a loop output so you can effectively get 4+1 outputs.

A DC input connector and fuse is provided for using this board as a P-DMX injector.

I have provided an LED to indicate presence of the 5V power.

The P-DMX voltage can be disconnected from the RJ45 sockets by simply removing the fuse.

Board size is approx 100mm x 35mm and it screws neatly into a Jaycar HB6122 plastic enclosure.

 

[Slite]

Nice... now for a complete novice... what does it do?

I assume since it is a "splitter", it takes one incoming DMX signal ans sends that to 4 controllers, or?

 

[XDU]

Nice David. Can you outline the performance differences between this board and the isolated version please.

 

[David_AVD]

Nice... now for a complete novice... what does it do?

Yes, it is for distributing DMX signals. You can loop in and out of some DMX controllers, but this isn't always convenient due to the physical layout. eg. You might want to send your DMX signal in a few different directions (in a "star" pattern). Doing this passively (without electronics) is not recommended and can lead to unreliable operation.

Can you outline the performance differences between this board and the isolated version please.

The other (larger, more expensive) splitter has each output electrically isolated from each other and the input. This can be important for layouts where the DMX controllers being fed are at different ground potentials. A major fault on an output of an isolated splitter will usually only damage that output and stop nasty voltages feeding back into every other out and the input.

This design is non-isolated. If you feed a nasty voltage into the input or one of the outputs, that fault voltage is quite likely to propagate and damage other connected equipment. For some application this is not a problem as the connected equipment is all low voltage and fairly risk free.

This design is much lower cost as it need no DC-DC converters, has less driver chips and a smaller PCB. It can also distribute the P-DMX power from either the input or a separate supply. The overall P-DMX power capability is still 2 Amps at 35 Volts.

So in a nutshell, if you want cheap and simple, this design is for you. If you want the protection of an isolated design, the more expensive isolated version is what you need.

 

[David_AVD]

Prototype is built but not tested yet.

 

[David_AVD]

I've added details to the wiki:

http://auschristmaslighting.com/wiki/APC756

 

[David_AVD]

Prototype tested and silly routing error fixed. I have a couple of the revision A boards built and available for sale. ($44 each including GST)

 

[mmkooiman67]

Hi David,
I am intereseted in one of these splitters. Do you ship to the US?
I am in California.
Thanks,
Mark