Z79Forth is a project that originated with the revival of hardware design for practically anyone interested in the field. The Arduino project was instrumental and I did build from there and various embedded electronics experiments up to an ESP8266 based weather station. That device was programmed in LUA (an interpreted/compiled language designed by PetroBras) and still lives on in the lab. It worked as a battery operated device for about a month in the field, i.e. below my rooftop, and demonstrated a very tangible reality: power management is the last thing a designer wants to think about but it is essential. I ended up re-focusing the project on that particular aspect of the system, using NiMH rechargeable batteries and a solar panel. Under favorable weather conditions (southern exposure of the solar panel), I estimate that the device should be able to work for as long as the batteries will recharge--about three years. However, I have yet to confront this with reality so this remains mere speculation.
In essence, the power management system takes its input from a solar panel, which output is fed to a Max 16910 12 volt linear regulator. The 16910 is an awesome piece of technology. It is meant to be used in automotive applications and can drive up to 200 mA. Its downside is that it comes in a TDFN-8 package (physically 3mm x 3mm) and is an SMT component. That would not qualify the beast as a DYI part, were it not for breakout boards sold by artekit.eu. This is an Italian business that strives to combine art and technology--we need more of those! In any case, once you have the breakout board, you're not out of the woods yet. I had to resort to my dad's former professional connections to have the 16910 assembled to the breakout board. All it took was precise preparation, component placement and a trip into the oven.
Down the power management path is an LM317 regulator used as a current source designed to provide enough juice to recharge the NiMH batteries. This is accomplished via a comparator (LM283) used as a Schmitt trigger. This relies on a reference adjustable voltage source. That particular component was sourced from Nat Semi, which appears to have been absorbed by TI in 2011--so it goes...
My notes about this date back from more than 4 years ago and they are sparse enough not to allow me to elaborate more on this topic. A p-channel mosfet produced by SuperTex (VP3203N3-G) also was involved in the system. It goes without saying that no animals were hurt in the process!
I end up spending a lot of my time on TI's web site looking for reference data. I think I could have been a hardware person too. Things just did not work out that way.
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