Sunday, 22 February 2015

DIY-Duino – The minimalist Arduino DIY

I’ve been looking for a simple project to play with since moving states. My goals for a simple project would be:

  • Extend my current knowledge and experience;
  • Useful in terms of my other projects;
  • Something that I haven’t tried before;
  • Uses components that I have on-hand

While hunting around for projects to play with, I found the “DIY-Duino” on Instructables by robonerd ( The DIY Duino is a simplified Arduino clone that works on a single sided PCB and has a minimum of elements ( a couple of resistors, a couple of ceramic and electrolytic capacitors, a 16MHz crystal, a bunch of female pin headers an LED and a pushbutton switch).


This project was a leap of faith for me because I was using someone else's design where the circuit template was a bitmap image (all of that nasty antialiasing means that the edges aren’t terribly crisp, compared with a raster image).

The first step was to transfer and etch the board. This was done with a reasonable amount of success. My only problems were with the antialiased image tending to make bridges between some of the close solder pads. That’s OK … I was expecting that.

I also had some gaps in some of my traces, that was down to the toner transfer and entirely my fault. I ended up bridging the only significant gap with a piece of cut-off wire (a leg from a previously used resistor … I keep most of my cut-offs for this purpose).

My longer term goal for this board will be to drive an automatic watering system for my veggie patch (I may need to make a few more) and will connect in an SPI (or I2C) network.

After the etch/inspection and correction process, it was simply a matter of populating the board.

Robonerd used jumper wires as bridges on the board (there are three of them) whereas I used 0Ω Resistors. The main reason for this is that I’m not all that keen on the appearance of cut-off jumper wire on the component side of the circuit … plus, the resistors are better insulated. Apart from that, it is an entirely personal choice (AFAIC).

When the board was all populated and soldered up, I got down and did some testing.

The voltage between the input power and the LM780 was 7.89V (battery not at full charge). The voltage between the LM780 and the 2nd capacitor was 4.98V, well within the 5% tolerance for the LM780 and safe for the ATMEGA329P chip.

Next, I did a continuity test throughout the board and found that all of the traces were good and the pin headers were correctly connecting to the DIP28.

Also, I made sure that the LED indicator did was it was supposed to do.

I will still need to test the circuit with the ATMEGA328P in place, but I kinda have to wait until my AVRSIP arrives (I just bought one from adafruit).

Well … that’s it for now. I’ll report later on how the circuit performs as a Duino clone.

Tuesday, 10 February 2015

New Toy!

Today, my wife’s surprise for me arrived. I had NO idea what it was … she kept telling me that I’d love it and that it was something that we had spoken about previously.

Turns out, she was dead right … I love it!

My surprise was a USB Digital Microscope (50x optical 200x digital magnification).

My eyesight has been getting poorer over the last couple of years and I’ve been getting more and more into wanting to solder SMD … in fact general soldering was only happening because of my 20x desk lamp/mag. It seems that, as my interest/need for closer and finer work has increased, my eyesight has degraded correspondingly, ah the joys of getting older.

The stand that comes with the device is nice, but not that practical. The first thing that I did was take the magnifying glass off one of my “Third Hand” tools and mount the microscope on that.

plugable - Digital Microscope

That lifts the scope end of the device up by about 10 cm, giving me enough room under the scope to actually work.

Next, I played with the software that comes with the scope. It’s pretty simple to use, but it has enough functionality to make it very useful.

Now I can …

look at components on an Arduino clone and identify them.

freetronics eleven 01

freetronics eleven 02

look at my SMD components in their packaging (and identify them)


some NE555 SMD

SMD 2N2222 Transistors

0805 2N2222 transistors


0805 Super bright White LED

Identify Diodes

IN4148 Diodes


See the colours of resistors … although, I’m still colour-blind. I’m still taking it on faith that these are 10Ω resistors

10 Ohm Resistor

One day, I’ll write some software to identify the resistor by colour … ‘till then, I’ll use my multimeter for that.

Look at some of my soldering work and identify the IC type


ATTiny85 Shift Register sub board

As well as inspect my soldering and printed circuit boards

Round LED board

attiny84 shield traces

Overall, I am very happy with my present … now I need to set it up on the laptop on my electronics workbench. I probably also need to make a better stand for it. I’ve got a mini camera tripod, maybe I can make an adaptor for the attachment … hmmm … gears are whirring in my head.

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