WDØDXD

In part 4 of our Power Management Unit Build, we start to wire things up.  There are essentially two separate sections we have to wire.

First we wire the power to the power supply and then to the relays, fuses and power poles.  I have a fuse that protects the hot side of the power supply and then each port has a 10 amp fuse installed on the hot side to protect the devices attached to the unit.

I show how I don’t trust the crimp connectors, so I remove the plastic insulators from them and crimp, solder and finally use heat shrink tubing to protect the connectors.  I also use WAGO LEVER-NUTS for the first time.  I am really happy with how they work and plan on using them again.

To wire up the connections for the controls and the Arduino, I use jumper wires from Pololu and some of our own connectors from Flatwater Trading Post.

The 5v power supply is also hooked up.  I have a heatsink on the LM9805 since it runs so hot.

At the end of this episode we have the Unit running like it was on the breadboard.  So we have to finish the wiring of the momentary switches, port LED’s and the current indicator circuit.

We will do that in Part 5 of the series.

Part 3 of our Power Management Unit Build covers mounting the switching power supply, circuit boards, Arduino and cutting some more holes in the back panel.

First I mask off the back panel and measure the holes for the USB port and Ethernet port.  Then I use a Dremel tool to cut the holes out.  It takes a while to cut the holes, so I need to investigate alternate ways to do this.

After that is done, I lay out the components in the chassis and drill the holes for mounting.  I am careful to use screws that don’t protrude too far below the bottom of the chassis so that they don’t catch on any other equipment when I slide the unit into the rack for mounting.

I also use nylon washers on the project boards when mounting them using metal stand offs.  I am hoping to avoid shorting issues by doing this.  I mount the switching power supply using some “L” brackets that I have made with a 3D printer.

In part 4 we will start to wire the components together.

In part two of our Power Management Unit Build we are going to start constructing the front and back panels of the case.

To start I apply painters tape to the front and back panel in a semi successful attempt to prevent marring of the panels.

Then I use product spec sheets and a caliper to layout the component placement on the panels.

Finally I use a drill press, air hack saw and a Dremel tool to cut out and finish the panels.

In working on the panels I learned a couple of things.

1.  I need to be more precise when cutting out holes with the air hack saw.  I spent a lot of time with the Dremel tool making the cutouts larger.

2.  I will probably need to put two layers of painters tape on the panels.  The air hack saw bounced around a lot and marred the panels.

3.  When drilling the holes, I need to stop and remove the shavings as I go along.  In some areas, the shavings scratched the panels as they turned on the drill bit.

I would really appreciate it if anyone has any suggestions on how to do a more professional job on this process.  It looks ok, but I would like to have a cleaner more finished look as I move forward.

In part 3 we will mount some of the boards and install the components in the front and back panels.  I also still need to cut holes in the back panel for the Arduino USB connection and the Ethernet port.

This is the part 1 of my Power Management Unit Build.  The purpose of this project is to create a power center for my homebrew Amateur Radio station so that I can control and monitor it directly from the unit or over an IP based network remotely.

I will accomplish this by employing an Arduino micro controller board that we sell at flatwatertradingpost.com.  The components in the PMU are as follows:

A 40 amp switching power supply purchased off the internet.  It features adjustable voltage from 10 – 13.8V, line and load regulation and Hiccup mode (recovers automatically after fault conditions).

I looked at building the power supply myself as I wanted a switching power supply due to is size and weight.  I found some plans on the internet.  The closest was a design by Manfred Mornhinweg XQ2FOD published in QST in the December 1998 issue.  It looked like what I wanted, but you had to wind the transformer yourself, and I didn’t feel that I wanted to tackle that at this time.  This project is modular in it’s design, so if I decide I want to build the power supply myself at a later date, I can then just drop it in place of the current supply.

The next major part of the unit is the Arduino Mega 2560 board.  I will be using it to control the other components in the PMU.  I have written most of the code and will post it as soon as I have finished it.  There is also a Ethernet shield.

Then we will have a 5v power supply to drive the Arduino, 5v relay board and the back light of the LCD.  There will also be a voltage divider to measure the output of the main power supply.

The front panel will consist of an on/off switch, LCD display, 4 momentary switches to turn the ports on and off and 4 leds to indicate the status of the ports.

The back panel will consist of a power cord receptacle, a fuse block and a set of power pole connectors for each port.

In the video I will show the panel parts and the bread board setup that has been completed so far.

In the next edition of this series I will actually cut out the front and back panels to start construction.