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I am still busy with my DMX splitter. The circuit is (at least for me as beginner) quite exhausting to hand-solder. See circuit below (sorry for my 'artwork' as some used to call it, it benefits me a lot to locate exactly the positions to wire).

I spend several hours to one DMX output PCB. As you can see 4 of them are quite similar.

I was wonder, how worthwhile it can be to make some 'default' building block DMX and/or MIDI circuits and order them.

Let's assume I want to put both a DMX in and DMX out on one PCB, but I want to hand wire the connections between them, to be able to use them

  • as DMX input only (and not using the DMX output part)
  • as DMX output only (and not using the DMX input part)
  • as DMX input and output (possibly by handwiring or use some jumpers to be able to connect the input and output

The PCB I need to order would be a combination of what is shown in the left/right PCBs marked with BOTTOM (which is a DMX input (left) and DMX output (right).

The reason is that ordered PCB normally have to be ordered by 10 so I benefit from equal designs.

The same later for when I'm going to incorporate MIDI (like making a MIDI in + out + thru on one PCB, but being able to use them in any combination.

Would this be useful (with the use of jumpers) or is it better to make the PCB's minimalistic?

(btw, for now I'm continuing handwiring, because I want to have this project finished, getting some more experience with soldering, and also because I never ordered a premade PCB, no knowledge about Kicad or other application that can generate Gerber or alike files needed to order a PCB).

enter image description here

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    \$\begingroup\$ Usually for multiple configuration PCBs you would use jumper resistors or 2 pin headers with shunts if you want to be able to do them "on the fly". Regarding PCB costs, board area, single/double sided copper, quantity, production time all factor in. Depending on your requirements, (eg no ground plane required) you might be able to use a single sided board, it makes the through hole connector points a bit weaker, and you have to have the components "flipped" to the underside of the board with respect to the connectors. That's because you don't have plated-thru holes or pads on the other side \$\endgroup\$ – isdi Oct 21 '18 at 21:07
  • \$\begingroup\$ @isdi thank you for that info, I see at jlcpcb.com/quote that the price for single or double side is the same. Not sure what a 'ground plane' means yet. I need multiple grounds for DMX (one separate for DMX input, and DMX output, they are isolated). \$\endgroup\$ – Michel Keijzers Oct 21 '18 at 21:58
  • \$\begingroup\$ ground plane is a layer of copper that covers most of a layer of a PCB, it's useful when signals of several megahertz are involved. \$\endgroup\$ – Jasen Oct 21 '18 at 22:38
  • \$\begingroup\$ If you're not in a rush, small PCBs are so inexpensive that custom boards for everything you do are quite feasible \$\endgroup\$ – Scott Seidman Oct 22 '18 at 0:13
  • \$\begingroup\$ @Jasen thanks for the explanation, than in my case it would not be needed, MIDI is 31,250 bps, and DMX 250,000 bps. \$\endgroup\$ – Michel Keijzers Oct 22 '18 at 0:40
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You've got 4 output boards that are essentially identical. If you design an output board that mounts directly onto the power supply module they can be exactly identical and do not need any jumpers

You could probably do the input board on the same PCB design by adding another DIP8 outline with pins 3 and 4 connected differently and add pads for the indicator LEDs too.

Then the only interconnect needed is the signals to the opto-couplers and the connections to the DMX jacks.

I don't think you need a full 3W to drive an RS485 line, more like 0.5W (at 5V drive) I'd look into isolated DC-DC converters eg: B0505LS then you could run the whole thing off a single 5W supply

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  • \$\begingroup\$ Thanks for this answer, the above is just an example of what I'm currently making, but your tips like also putting pads for the LEDs would be good. I have to search in history questions, but there was a problem with B0505LS modules. \$\endgroup\$ – Michel Keijzers Oct 22 '18 at 0:42

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