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This is a very simple and straightforward explanation of a SEPIC converter topology for a power supply This is good for when the power can be lower or higher than the voltage you need (as in maybe a solar panel supplying a battery and circuit). MPPT charge controllers work similar to this For my ATmega328 power source, I'll probably do this since, most of the time, it will also probably spend a lot of time connected to a solar panel for simple outdoor projects 15 comments
A lot of Arduino projects use the 7805 voltage regulator, but if I'm only powering the ATmega328 chip and nothing else (not even the LED or optocouplers), I think I can get away with using a 78L05 16MHz+ speed is supported between 4.5V - 5.5V, but (according to the datasheet) running on the internal 8MHz clock should only draw 2.7mA Including the external 16MHz crystal, it may be 80mA+ total (30ohm ESR crystal, 2 - 22pf caps, and 10K resistor) 78L05 can support up to 100mA so it's just enough It's oddly liberating to design a circuit schematic in Notepad Next challenge is making all that fit into this 3x7cm perf board I'm not too worried about power dissipation just yet, but I'm going to try and orient all the MOSFETs to one side so their heatsinks away from the rest of the board I'm half tempted to try and squeeze a different version into this 2x8cm board as a fun challenge, but that may be for later Actually, I got this board to try out a minimal ATmega328 setup with just the crystal, resistor and the 2 capacitors Added a project page for the power supply. Just a place to put down ideas while I sketch them https://github.com/cypnk/Cabin-Life/tree/master/Power%20Supply I'm always uncomfortable when adding disclaimers to anything I.E. "Not responsible for sparks, fires, or worse, by using my poorly thought out ideas in this thing thing I wrote at 9AM on a Sunday while running low on coffee" OK I think we can call it a day This *shouldn't* immediately blow up after connecting power This was a challenge and a half without a working oscilloscope. I really can't afford a new one right now so a lot of the component values are blank (or wrong) for now (Stream of consciousness hardware hacking is a bad idea, kids. Don't try it at home) I'm still liking the Notepad schematic idea since I can freehand pretty much everything and it's not going to complain NASA's Through hole soldering guidelines might come in handy when it's time to assemble components for my power supply If I'm building it to function way off in the woods, exposed to all manner of whatnot, soldering is probably the least of my worries. But why allow the possibility for small issues to accumulate into big problems https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/601%20General%20Requirements.html  @cypnk omg I love that these workmanship standards are just out there to read  @darius @cypnk as i remember, this discussion came up at sparkfun when we realized that people were *actually* sending our stuff to space on cubesats and the like. which is definitely, like, a holy shit cool moment, and then a lot like when you find out people are using it for medical devices you go wait, are you sure you want to do that, because i probably wouldn't do that |
Gregory's Server
This is a very simpler solar charge controller built with a 555 timer as the main handler
It uses very basic parts: a few resistors/caps, a 7809 voltage regulator (which is almost as common as the 555), and an IRF3205, which is an N-channel MOSFET, but think pretty much any other high current one would work there too
This might be a pretty good replacement to those Arduino based charge controllers. Actually, the Arduino ones use the same exact MOSFET as this
https://www.youtube.com/watch?v=A75cE_k9cVw
This is a very simpler solar charge controller built with a 555 timer as the main handler
It uses very basic parts: a few resistors/caps, a 7809 voltage regulator (which is almost as common as the 555), and an IRF3205, which is an N-channel MOSFET, but think pretty much any other high current one would work there too