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Build your SEGmeter

published, Jun 27, 2010 3:51am
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Wondering how to go from this to SEGmeter, measuring, collecting and sending your energy data into the tubes? Well this guide will take you there.

created on: 07/26/10


Fresh SEGmeter, ready to rock

This is a first in a series of build guides, where we plan on taking you through the end to end of making SEGmeter, how to program it, set it up, install and start collecting energy data. This will include:

  • How to make SEGmeter from all it's little component and parts. This includes:
    5mm Current Sensor kit
    Zigbee kit

    Temperature kit
    Relay Kit
  • Programming Arduino with the SEGmeter Aiko code
  • Program the Zigbee to chit chat over the radio waves
  • Flashing and setting up the OpenWRT SEGbox gateway
  • Installing SEGmeter in your switchboard.
    ...and probably a whole bunch more.

It's also probably worth noting that I'm not using any special tools or techniques.  The whole idea is this little baby can be made by almost anyone with a soldering iron, pliers scissors. 


Get SEGmeter!

First you will need SEGmeter, and some SEGsensors, so head over to the SEGshop


Right-O lets get to it and make it!

First Up, I like to give my board a little clean with some Metho, apart from putting my mind at ease - it also makes sure any dust or other stuff is out of the way before hot solder finds its way into all the little holes.

created on: 06/27/10

is clean, is good, makes for happy solders

Current Sensing Componentry.  SEGmeter employs a high pass and low pass filter to get a better signal for the Arduino to process.  The basic components that comprise this are as follows:

created on: 06/27/10

for a moar betteror signal, we use magic.

So, I knew you couldn't wait, first up we will install some resistors.  These are a low value 22 ohm, used for part of the low pass filter circuitry in the SEGmeter.  You will need as many of these as you will SEGmeter channels - 6 per SEGmeter.

created on: 06/27/10

unlike others, these resistors aren't futile

Now it's possible to identify the resistors (current kits will come with these blue metal film resistors) we can put 'em in!

To make things easier I like to bend the legs first, and with the tape still on the ends this is a little time saving step.

created on: 06/27/10

this is much easier if you can imagine there is no spoon.

When we make the lovely white screen prints for SEGmeter, we didn't quite think of everything... So in case you were wondering, I got out my sharpie marker and documented channels 1-6.

created on: 06/27/10

from left to right, one, two, three...

And poke poke, you get the idea. This is called through-hole componentry - for a reason Laughing

created on: 06/27/10

Insert all the resistors, for all your channelz.  Then flip the board over and bend their leggies.  This stops them falling out during the soldering process.

created on: 06/27/10

When I learnt to ski, Hans told me to bend zee kneez

A little word about safety.  In my toyshop I have a rule - if it's stinky, it's bad mokay.  Solder generally has lead in it too (unless you live in the state of California and have contraband).  I use a high quality charcoal based respirator in these situations.  Do your lungs a favor and protect them from the nasties.

created on: 06/27/10

just say no to stinky things.

Some soldering tips 101

  • be patient, slowness makes for goodness
  • give the pad, and legs time to heat - I count to 2 before applying solder
  • apply the solder to the leg/iron and allow the solder to flow into the joint, a rhythm will be found
  • less solder is best, allow another count to 2 before removing heat to allow the solder to flow into the joint

created on: 06/27/10

shazam, we commit solder!

After all the leggies have been soldered in, we trim them.  It's important to be careful doing this to not damage the track or cause a short circuit between the solder joint and the ground plane on the SEGmeter.  Be careful of the leggies jumping when cut and landing inconveniently in one's eyeball.

created on: 06/27/10

long haired SEGmeters are considered out of style.

The BIG capacitors we use on the filter circuitry are 1uF jobbies.  These form part of the low pass filter arrangements. 

created on: 06/27/10

forcing electrons to jump through some hoops, only the best will do

Just like the resistors, they go into the holes marked 1u, have their legs bend and soldered.

created on: 06/27/10

the caps stop the resistors from getting all lonely

We install some more capacitors, this time the 100nF ones.  They go in some funny places, and some are used for power supply smoothing and other general circuitry goodness.  Don't fret, their placement is all identifiable, we got this labeling correct.

created on: 06/27/10

caps ON!

The final part of the filter circuitry comprises some 100k ohm resistors that ground the analog inputs to Arduino's analog-digital converters.  There are six in total that plug into two places, here and here.

created on: 06/27/10

two locations where some high resistance can be found on SEGmeter

We chose to use 3.5mm stereo connectors to plug in the current sensors for a couple of reasons. 


  • easy pluggability
  • they support both our passive current transformer and active hall effect current sensors.

For these, it's important to know the connections:

  • Tip is the positive signal from the sensor
  • Middle ring is 5V - for the active hall effect sensor (this can be disabled with a hack)
  • Base is the ground

Installation of the stereo jacks can be a little bit finicky, one method I use to make it nice, is to take a paddle pop stick and a small clippy thing, and solder on the outer ones.  When these are all on, I can then use the clip and solder in the other stereo jacks in the middle.

created on: 06/27/10

these are not wired for sound.

With all the stereo jacks in, it's time for the power jack.  I find a nice blob of blue tack holds this in place until the solder has made the connection fast.

created on: 06/27/10

guess where these are made?

What's an electronics project without some blinking LEDS?  Well SEGmeter gives you three of 'em.  The are:

  • Red LED for power.  This lights when it's on.
  • Yellow LED that blinks, letting everyone know that the energy is being sampled by flashing
  • Green LED for the relay power, this will light up green when the relay circuit is ON!

created on: 06/27/10

what did the man with three leds say?


LED's don't work when they go in backwards.  Don't let this happen to you!

The long leg is the positive side, and the short leg negative.  This indicator helps you know where to put the good leg first.

created on: 06/27/10

avoid LED failure on your SEGmeter, put the long leg here

Then the 150 ohm resistors are used to slow down the flow of electrons to the LED's making them work as advertised.  They go here:

created on: 06/27/10

pop em in here, and all will be swell.

Phew!  Well that was a lot!  I think now it's time for a little rest before we get on with the next in this little series, that will be

Build out the SEGmeter Zigbee kit






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muy buena la info. me sirve perfectamente.

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