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Project: A Breakout Box For The Neptune Apex

Neptune Systems sells an accessory for their aquarium controllers (in my case, the Apex) which they call a Breakout Box. It functions as a continuity checker - allowing up to six devices (in effect, switches) to be monitored by the Apex. The On/Off state of each switch connected to the box is continuously reported back to the Apex, allowing a user defined program instruction code to react in a predefined way according to the state of each switch. The simplest example might be a float switch.

Placing a float switch in a sump and connecting it to the breakout box would allow the Apex to control a top-off pump - turning the pump on and filling the sump with R/O water when ever the float switch "opened" as the water level dropped below a predetermined point. With another float switch (set just a little higher in the sump than the other one) and an additional connection to the breakout box, the Apex could be made to shut off the top-off pump when the water level in the sump had reached the "full" depth (the upper float switch closes).

Neptune's device sells for $40. A fair price - but, if you have a little experience with a soldering iron and an hour of free time, you can easily make one for half the cost. It's an easy project, so I won't go into a lot of detail. It's mostly self-explanatory.

What parts do you need?

The connection on the Apex for the Breakout Box is via an 8 pin mini-DIN connector. Each connection (for switches) to the box requires 2 wires - let's call them active and ground. Taking those facts into consideration, we need:

  • a cable with an 8 pin mini-DIN connector. These can be had cheaply on eBay in the form of a legacy Apple MAC serial printer cable. Get a 6ft cable and cut it in half - you only need a plug on one end.

  • a project box. Pick one up at Radio Shack. Their second smallest model is what I used.

  • 3.5mm mono headphone socket (6 pieces). Get panel mountable or circuit board mountable sockets - either type will work. I found these very cheap from Hong Kong on eBay.

  • 3.5mm mono headphone plugs (as many pieces as you need to complete your desired switch connections). Again, I found these very cheap from Hong Kong on eBay.

  • a 3 inch length of 16 or 18 gage wire, missing in the pic, below.

  • also missing, in the pic below, is a rubber grommet to hold the mini-DIN wire firmly in the project box.

Here's a pic of what the listed parts look like:

Assembling the Breakout Box

  1. The first thing to do is drill 6 holes in the project box to hold the 3.5mm sockets. The size drill you should used will depend on exactly which sockets you purchased. For most sockets the size is about 1/4 inch. Depending on your preference you can mount the sockets on the top of the box or on the side - I chose the side.
  2. Also drill a hole for the mini-DIN cable and mount the rubber grommet.

  3. Mount the 3.5mm sockets into the holes you just drilled in the project box.

  4. Strip around 3" of the insulation off the cut end of the DIN cable. You will find a metal mesh insulation layer inside - cut it off, its not required.

  5. Strip the insulation of the 3" length of 16 to 18 gage wire. This will be used to connect all the sockets together, using the ground terminal. Each mono socket will have at least 2 terminals. One for the tip of the mono plug that fits into the socket, and one for the base of the plug. For our purposes, let's call the tip +plus and the base -ground.

  6. Solder the 3" piece of wire to the -ground terminals along all six sockets. Start at one outside socket and continue to all six, leaving a 3/4" length of wire sticking out past the last socket (see the pic of the completed wiring, below).

  7. The Apex is configured so that pins 1,2,3,4,5,6 on the mini-DIN plug correspond to connected switches 1,2,3,4,5,6 when referred to in the controller's programs. Pin 7 is not used and pin 8 is the common ground. Looking at the plug, with the pins facing you this is the setup:

    The 8 wires in the mini-DIN cable will be color coded. You need to match the colors with a particular pin. Do this using a multi-meter in continuity (Ohm) mode, or you can use a battery and flashlight bulb. Once you have identified which wire corresponds to which pin, you can begin soldering the wires to the +plus socket terminals. Decide which end of the row of sockets you want to make the start and solder wire 1 (one) to the +plus terminal. Solder wire 2 to the +plus terminal on the next socket in line. Continue to the end. You can cut wire 7 off completely as it's not used. Solder wire 8 to the end of the ground wire (the 3/4" you left free for this purpose). When you have completed all the soldering, the inside of the project box should look something like this:

  8. Mark the outside of the breakout box with numbers identifying the 6 ports and screw the lid on to the box:

That's it - your breakout box is finished! Take a look at the Apex's user manual (or download a much better manual here) for instructions on how to use it. Also, I am definitely not the only person to think of DIYing this piece of equipment. Among others, there is a thread on Reef Central with more detailed instructions - check it out.



Harry says...
What are the dimensions of the Project Box?
GlassReef: 4" x 2" x 1" high
13th April 2016 8:14pm
DonL says...
Great little project! Just finished mine. Works a charm.

Thanks and keep up the good work!

GlassReef: Thank you, Don. You comments are much appreciated.
17th December 2010 11:46am
Chad says...
Nice project. Mind saying what you paid for the jacks and plugs?
GlassReef: I can't remember exactly. I can say that it was around $20 for 20 jacks and 20 plugs together - and that was with shipping. So, all up, it was around 50 cents apiece. Very cheap! Normally, you'd have to pay $2 or $3 for each piece. Buying in bulk definitely pays. Smile
5th October 2010 11:13am

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