{"id":132,"date":"2017-08-06T18:15:57","date_gmt":"2017-08-07T01:15:57","guid":{"rendered":"http:\/\/eequalspi.com\/?p=132"},"modified":"2017-08-06T18:16:06","modified_gmt":"2017-08-07T01:16:06","slug":"powering-the-iv-11","status":"publish","type":"post","link":"https:\/\/eequalspi.com\/index.php\/2017\/08\/06\/powering-the-iv-11\/","title":{"rendered":"Powering the IV-11"},"content":{"rendered":"

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In our last adventure, we lit the IV-11 with benchtop power supplies. Nice to show that we know how it works. Now, it’s time to build a project around it. After some thought about what I would like to display with a single digit seven segment display, I chose a thermometer. Taking up a wall outlet doesn’t make much sense either, so it would have to be battery powered and fairly energy efficient. To drive the IV-11, I’d need a 25V supply as well. Fortunately, in my parts bin, I had a couple of tricks up my sleeve. First, I had a handy $2 boost supply from china<\/a>. I also had a spare Murata 7805 <\/a>replacement, which provides a drop in replacement for the classic LM7805 linear regulator, but at a higher efficiency (and without the strict need for the off board filter caps)!<\/p>\n

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Boost mode power supply from eBay to make the 25V supply rail from a battery source.<\/figcaption><\/figure>\n

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The 5V rail would provide power for several things. Most obviously, it would supply power to the microprocessor (an Atmega 328P) and sensor (a DHT11<\/a> module from OSEPP, picked up at my local Fry’s — more on that in a later post). Additionally, the 5V rail would provide power for the filament — this would be more efficient than some sort of resistor divider down from 25V.<\/p>\n

The final part of the power supply would be the soft power module. It’s a circuit I’ve used before, based off the Dave Jones soft power switch.<\/p>\n