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Power considerations

Voltage Regulator

Why because the Arduino has one ? Well, the Arduino 2009 has a good one, to my personal experience. The arduino pro has a lame one ... meaning it dies by iteself if you feed it with 9V. So better pre-regulate the voltage before feeding it.

LM7805

THE voltage regulator. Feed it with something over 5V and below 12V (depends on the model, can get much higher), you get 5V out.

LM317

Variable output voltage regulator. Give it a few resistors, and you get whatever voltage you want!
Formula is Vout = 1.25 * (1 %20 R1 / R2)
Schema and explanation here...

Constant current


Battery life


Power consumption

... of batteries or IC (low power modes)


... of AC or wallwart


Optocoupler / フォトカプラ


Voltage doubler / Step-up converter

Boost converter



Joule Thief


With an IC


Wall wart

A common problem is the power source for my projects. Nearly all need their 5v regulated power source. Not such a burden when it's anyway plugged to USB or meant to be fed by a wallwart. But when it comes to the projects like Clapclap 2313 for instance that drives already a power plug, it forces me to do some complex, annoying and questionnably safe operations "ghetto style". One good solution I wander around for some time is to open one of thoses small wallwart and connect directly to the right pins (as much for the AC and the DC). The following tutorial is not so much a surprise (kinda guessed what I would find or at least how to use what's inside a wallwart) but it's the "red berry experience" (as Dr. House explained) : seeing someone doing makes you see that you can do it too...

The best thing : scavenge the trash bin. Here in Japan we sort stuff, electronic devices go to a special bin in my building threw away once a week... I already got more than 10 wallwart, 2 cd player (lots of good stuff inside), one dvd player, etc etc ... RE-CY-CLE ! It's worthless for you but so much fun for me.

Protection : how to stay safe



AC : Dimmers


Batteries Lithium ion : use them without exploding

We all have some of thoses laying around ... let's give a try.

Transfer info over the AC wires


Energy harvesting

From solar cells, wind, water flow... See also Voltage doubler / Step-up converter here above and Solar panel power.

Current sensing

All content on this site is shared under the MIT licence (do what u want, don't sue me, hat tip appreciated)
electrogeek.cc ~ Formerly known as Kalshagar.wikispaces.com (AlanFromJapan [2009 - 2019])