First Truly Winters Day in Durban

Wow.

After several hot, sticky and sweaty months in Durban I think the cold weather is finally getting here. Not that it really gets cold in Durban but hey cold is better than hot therefore cooler weather is great.

Well despite spending most of my day editing wedding images and the like I still managed to get some time in on my development and have managed to throw together a few android apps to control various aspects of my house and entertainment system using my phone the HTC One which happens to have a built in IR transceiver. ;-)

I will be starting development on my home control system soon and am still in two minds whether I want to go Android or Linux. Its a tricky choice to make as both have their pluses and minuses.

I would be glad to hear from anyone who is doing something similar.

Cheers for now

Dionne

UPDATE : 12/04/2014 – Prototyping Platforms

Hey everyone.

What are prototyping platforms and what is available to those out there wanting to learn and tinker with digital systems?

When I first started in electronics there was no such thing as a prototyping platform. Sure we had components and kits that could be had from places like A1 radio and the likes but everything we wanted to do or learn was a long process.

Information was still scarce and component info even more scarce. We used to use component books to look up component info etc. There was no internet and books where the only source of information. It was only when I was in high school that the internet really started becoming something that home users had and even then it was far and few between. SA was after all a late adopter.

Not going to dwell into the internet etc but lets just say anyone wanting to play with electronics now has it so much easier than 20 years ago.

In the image above from top left to bottom right:

1. PCDuino V2.0 – An Arm Cortex based Arduino compatible mini computer which is similar to the Raspberry Pi but much more capable and powerful.
2. LCD Sheild  - These shields are used on the Arduino platform for development and testing.
3. USBASP – This is used to program the AVR chips which Arduino and a few other platforms are based on.
4. Breadboard PSU – This is both a 3.3v and 5.0v breadboard Power supply. It is super handy for getting the right voltages from a single power source.
5. Freeduino – This is essentially an Arduino UNO with ATMEGA328P-PU microcontroller. I only prefer purchasing the Freeduino as it is cheaper and more customizable when it comes to assembly.
6. Arduino Pro – This is essentially a miniture Arduino board minus the USB port and FTDI chip.
7. IRF24L01 – 2.4ghz Radio Boards.
8. 10 Pin to 6 Pin adaptor.
9. FTDI Board – This essentially is a USB port for hardware projects.
10. Arduino Mega 2560 – One of the bigger Arduino Boards. Very capable and awesome for systems development.
11. Chipkit UNO32 – Technically this is a PIC based Arduino board. It is very Arduino compatible and runs most of the Arduino code however is far more powerful and capable with many more I/O lines compared to Arduino. The best thing is it costs the same. Please note that Arduino does feature more info and support and a much larger user base at present.
12. Couple of LCD panels and breakout boards etc.

Most of my hardware development thus far has been done on the ARM based board as well as the Arduino and Freeduino. I tend to develop on Arduino then build the project standalone using an AVR chip with the needed components around it. This saves cost and makes things more practical. I also tend to use the Arduino environment to create the HEX files which I prefer to burn straight to the ATMEGA chips without the bootloader which makes them faster and more efficient.

At present I am working on a standalone micro PC which can be attached to any TV set essentially turning it into a home automation system, multimedia player, decoder, Internet browser, Email system all based on a standard home television. This system is being designed for ease of use and stability and will be easy to use. I am hoping to have the system on demo within a few more weeks. Am awaiting the Arm Cortex CPU’s etc to arrive from manufacturer.

My recommendation to those wanting to dable with digital systems at a high level is to get your hands on an Arduino UNO R3 and start googleing and playing with the sample code avail to you in the Arduino IDE.

Cheers for now.

Dionne

The Humble MULTIMETER. What can one measure with it.

Hey everyone.

Despite being very tied up in high level digital development and various other projects I decided to do a small article about multimeters and what one can typically measure with one. I will also cover basic component testing etc in this post.

Multimeters go back many years. The volt meter and amp meter or ammeter predate all the fancy test gear we have available now days however as an engineering type I make use of one of my multimeters almost every day.

Below you can see my multimeters layed out: Please note that these pics are taken on cell phone so not best quality.

These are the four meters that I make use of the most.

If I am wanting to do data logging or analysis I generally go to my Uni-T UT71A as it has the capability of connecting to PC via USB which allows me to log voltages, currents or just about anything without being around.

Below is the UT71A closeup.

   

This meter also has a fantastic large LCD display and allows you to check voltages etc with very fine levels.

My spare meter is my little Major Tech MT24 which has seen me through many jobs, repairs and designs and is used fairly often when a small meter is needed on the bench to measure secondary signals.

   

I find this meter to be very accurate and great value for money.

My third meter and my primary bench meter (my go to meter) is my Major Tech MT1880 IV. This meter was a lucky find at a local second hand store and after a good cleanup she sits proud on my bench as my primary meter. Why this meter some may ask. Well its simple, clean and does most of what I need on a single unit. I also enjoy the analogue (digital) bar at the bottom.

   

The last meter and my least capable but still very capable meter is the TA EM5511. All the other meters here where well over R1000 each whilst this unit set me back about R200.00 second hand.

I will use this meter for my tutorial and article.

   

The first few things you will notice is that all my meters are Auto Ranging, they all have backlights and are all very multitask meters. The Auto Ranging feature used to be reserved for the high end meters however some of the newer low end meters also have this feature now days and it really does make sense to get one which is auto ranging as it does two positive things for you. The first is that you do not have to keep selecting ranges all the time so is convenient and the second is that your rotary button will not wear out as quickly as it will be used less.

I have pretty much gotten rid of my Fluke 77 and various other meters as I really was not using them half as much as these and these cover everything that I would want to cover in my work and experimenting.

Anyway this is not technically a review of multimeters, That will be done pretty soon as well as reviews of development boards, Oscilloscopes etc. All in due coarse. This is more a tutorial on multimeters and how to use them and what you can measure.

For this article I will be using the above TA multimeter as it is simple, clean and most probably closer to what many people starting out will be using. If you know what you are doing you wont be here after all.

So lets start.

On all meters you have what I call the mode selector which is usually a rotary dial with a whole bunch of options. If you have a autoranging meter then the options will be less.

Below a close up":

From left to right going clockwise you will see the modes as below:

1. OFF (Power Off Mode)
2. V~ (Voltage AC – Alternating Current) which is the kind of stuff that comes out of our wall sockets and out of step down transformers etc.
3. V= (Voltage DC – Direct Current) this is what comes out of batteries and power supplies that output DC power. This is what you will most likely measure a lot as this is cells, batteries, power supplies and so many other things.
4. OHMS (This is to measure resistance or ohms) Used to measure circuit resistance, component resistance and so many other things.
5. Diode / Continuity Test (In diode test mode you are able to measure the voltage drop of a PN junction such as a diode, transistor and various other devices. In the continuity mode it will beep if the resistance is below a certain value of around 30ohms.
6. Capacitor Test (This is limited on most meters but does come in handy for checking capacitor values and testing capacitors.
7. Hz% ( This is used for measuring frequency and duty cycle) For example if you wanted to use a microcontroller such as an Arduino to control the speed of a motor or brightness of a LED then you could use Pulse Width Modulation or PWM. In the case of Arduino this is usually defaulted to 490hz. You are then able to measure this frequency as well as its duty cycle. The duty cycle of PWM is used to control the amount or speed of the device or motor. For example at 0% duty cycle the switching mosfet or transistor would be off whilst at 100% it will be at full power or speed. This is the most popular method for using microcontrollers to control large motors or lights etc. More on PWM and how to use it in another article.
8. Deg C (Measuring temperatures of various devices)
9. mG (In the case of this meter it is used to measure the EMF from the sensor on the top of the meter.)
10. uA ( Measuring very small currents or Micro Amps)
11. mA ( Measuring Milliamps)
12. A ( Measuring Amps)

So basically with this little meter you can fault diagnose most electronic or electrical components, you can tinker with digital signals and various other things.

I am not going to cover the entire how to use a multimeter as this is more about showing you what can be accomplished using a humble multimeter.

As a field components level technician for many years working for one of South Africa’s biggest RF or radio frequency networks I learnt how to use a multimeter for more than it was originally planned and even went so far as to build my own probe devices for measuring RF signals and others.

I will upload a video to this post in due coarse showing you how to use this meter to measure various signals.

Go out and grab a multimeter. It will make your day, unless you already have one. ;-)

 

Cheers for now

Dionne