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.
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?
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...
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: