Wednesday, 15 October 2014

Bright Light

The Workshop

At home I've seconded a small corner of my garage for my work space.  

You could describe it as 'spartan' or 'functional' but in reality, 'cheap' is more accurate.  One problem with the bench is that it's poorly lit.

Saturday, 16 August 2014

Altium MultiChannel

Multi-Channel Rules

Just recently I was reading this post on the EEVBlog forum and thought "Ah ha!  I've done this before." Should be easy.  Famous last words.

So after spending a ridiculous amount of time workign out what the missing step was, I thought I'd better capture it for the next time I want to use it.


You use a multi-channel design in Altium when you have multiples of an identical sub-circuit.  QAll you need to do is lay out the one channel, and then you can duplicate the layout by 'Copy Room Formats".  This has saved me a ton of time in the past.


Altium uses a complex naming convention:

Monday, 4 August 2014

Multi Channel Meter, Part 2

From Idea to Implementation

What I really love about my hobby projects is that I can develop answers to questions that I can't explore at work.  20kW HF transmitters, Radar Installations all over the world, and Cutting Edge elemental analysers?
No worries.

Digitally Controlled GainIsolated PSU Choices?  Fergedaboudit.

In part 1, I detailed my path from the concept of a multi-channel volt meter, to a working system based on individual modules.  Here I'd like to talk about how I refined the design into my first prototype and then look at where I'm going from there.  Like Art, Engineering is never finished, you just chose a point to stop...

Sunday, 27 July 2014

Multi Channel Meter

So after all that background...

Recently I've blogged about DIY Isolated Supplies and Microcontrolled Analogue Gain, as these have been necessary building blocks for my latest project - a multi channel voltage / current meter.

Microcontrolled Analogue Gain

Digital Controlled Gain

For a long time I've wanted to implement a gain stage where I was able to alter the gain under digital control.


Back in my Uni days, I have to build an Automatic Gain Control circuit, and was greatly dissapointed that the trick there wasn't variable GAIN but variable ATTENUATION on the front end.  At the end of the day, that approach works well where i used it, but I always wanted to have true programmable gain.

But this was the case of a solution looking for a problem, until I decided that I wanted to build some test equipment that required programmable gain!  So, to test the theory I cooked up this:

It Worked!  Eventually!

Saturday, 26 July 2014


Coming Soon

I know I've been a touch quiet on the blog, mostly because I've been sidelined with other projects.

Blog entries for all coming but here's some preview pics:

Multi Channel Meter

Isolation Options

Isolated PSU

So if you find out you need to isolate your circuit, you will need to power it over the isolation barrier, and there are options out there to do that.

Finding myself in that position, and being a notorious tight-arse I started to look at DIY options.