Power meter optical pulse detection

I’ve always planned to monitor my electricity usage. I had previously (about a year ago!) ordered some power transformers from seeedstudio and a six channel ADC for simultaneous three phase current and voltage measurement but never got around to starting the project.

We’ve since had a “smart meter” installed which has a handy LED on it that flashes once every watt hour of energy is consumed. It also has and IrDA port on it but I believe the communications protocol is password protected and will report a tamper state if the password is tried too may times. Because of this, I decided it was best to optically interface with the meter, and best of all, I’ll be measuring the exact amount of power we get billed for. Unfortunately I won’t be able to predict the bill amount (in dollars) as the three phases that come into the house are billed at different rates while this LED pulses the combined usage.

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Posted in Electronics, Embedded Systems, Power monitoring, Projects, Wino-Board

Wiring up the ESP8266

Before you can program the ESP8266, you need to wire it up.

First things first, the ESP8266 uses a 2mm pin spacing so you can’t use a standard breadboard as these use a 0.1 inch spacing. It also uses 3.3V logic, so you need to use a 3.3V serial adaptor or a 5V one with a level shifter.

Ideally, you will need the following things:

  • USB to 3.3V TTL serial adaptor (I use an FTDI TTL-232R-3V3)
  • ESP8266
  • 3.3v DC supply (capable of providing ~400mA)
  • Small SPST switch – Optional to switch between Run/Program mode
  • Momentary push button – Optional reset button
  • 4 x ~10k resistors
  • ~100nF capacitor

I wired up my ESP8266 like this (Source: https://github.com/esp8266/Arduino/blob/master/doc/boards.md#improved-stability)

Note: The pin CH-PD is marked EN on the ESP8266 12E

Note: The pin CH-PD is marked EN on the ESP8266 12E

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Posted in Electronics, Embedded Systems, ESP8266, Projects

Introducing the ESP8266

About a year ago I put up some money for the Wino-Board kickstarter project, received my Wino-Boards and did nothing with them for 12 months. They are effectively a tiny Arduino board attached to the innards of an ESP8266 WiFi module.

I finally had a play with them last week and after making a few changes to the Wino-Board libraries (The current version could not do an HTTP GET), I found them very easy to use.

The more intriguing thing about the Wino-Board was finding out more about the ESP8266 module and that it is now possible to directly program the module itself using the Arduino IDE.

Front and Back of the ESP8266 (12E)

Front and Back of the ESP8266 (12E)

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Posted in Electronics, Embedded Systems, ESP8266, Projects, Wino-Board

Fridge Wiring

My Humidity controller finally arrived this morning so I’ve started wiring up the control box.

It's still looking like a bit of a birds nest, but I can assure you, It's safe!

It’s still looking like a bit of a birds nest, but I can assure you, It’s safe!

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Posted in Cheese Fridge, Projects

Fans in the Fridge

I’ve finally found a bit of time to get my fans installed in the fridge.

I’m still waiting on the humidity controller to arrive from China. Everything else took about 8 days to arrive, but the humidity controller has so far been 36 days – The tracking number shows it in NZ now, so it should arrive very soon.

I’ve lined one of the holes with a short length of PVC pipe, the other has a longer piece to reach lower to the bottom of the Fridge section – The longer length “sucks” air from the bottom of the fridge, effectively trying to fight convection and move the cold air from the lowest point back to the highest point.
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Posted in Cheese Fridge, Projects

Drilling vents in the fridge

When I was investigating the wiring diagram of my fridge freezer, I was also trying to find out if there is anything important in the divider between the fridge and freezer. Based on the diagrams I was confident that there was nothing in this area so I was free to drill holes.

I opted to put one hole in the front left and one in the back right.
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Posted in Cheese Fridge, Projects

Ordering parts for the cheese fridge

After working out how my fridge works, I’ve now decided what I’m going to do to make it into a cheese fridge.
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Posted in Cheese Fridge, Projects

Understanding how a fridge freezer works

The fridge I’m using for my cheese fridge is a fridge freezer, this means that during normal operation, the two boxes are different temperatures – around 20 degrees C.

I want both the fridge and freezer to operate at the same temperature, so first job is to find out exactly how the cooling system works. I’m not talking about the Vapor-compression refrigeration process, but the specific details about how this specific model works.

The circuit diagram is a good starting point:
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Posted in Cheese Fridge, Projects

Cheese Fridge project

Wow, almost six months since my last post! Yes, I’ve been busy.

I’ve recently started making cheese. Generally you start off making soft cheeses like Brie & Camembert. After a little while these cheeses no longer do it for you and you move onto the gateway cheeses such as Gouda. Before too long, you’re an addict and you need something harder – Yep, I’m talking Cheddar and Parmesan.
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Posted in Cheese Fridge, Projects

Petit Studio Raspberry Pi HDMI extender cheap cable fix

Note: This fix is NOT due to a fault of the Petit Studio Raspberry Pi Camera extension kit, it’s due to the use of cheap HDMI leads.

I brought some Petit Studio Raspberry Pi HDMI camera extenders from Tindie. These boards passively convert the 15 pin ribbon cable into a convenient HDMI connector so the cable can be extended using HDMI cables. It doesn’t convert the signal to HDMI, it simply uses the HDMI cable as an extension. Sidenote: The $5 shipping only took 4 days to get to New Zealand from Japan!

I brought some cheap 3m HDMI cables from a supplier on TradeMe and thought I was all set.

It turns out not all HDMI cables are made the same. The cables I brought work perfectly between a PC and monitor, but not at all on the Tindie camera extender.

A quick Duck Duck Go (That’s so much harder to use as a verb than Google) and I found a fix – There are meant to be shields for each data pair but in cheaper cables these are not connected. It’s an easy fix, just use the metal shield of the HDMI plug as ground…..

Or not..
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Posted in Electronics, Raspberry Pi, Weather Station