555 boost converter

Posted on Feb 4, 2014

Boost circuits are an awesome way to power microcontrollers. Instead of 4AA batteries or a 9V (usually regulated down to 5V or 3. 3V), you just boost one or two AA`s up to your desired voltage. The only problems are that boost ICs (like these two ) are a little expensive once you decide to make more than 2 or 3 of something, and the cheaper ones ar

555 boost converter
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e hard to find in packages that can be hand soldered easily. I stumbled upon one great solution here use PWM from a microcontroller. And Atmel recently introduced the ATtiny43U with a built-in boost converter hopefully this will become a trend and all microcontrollers will come with built-in boost converters, the same way they (mostly) all support serial, I2C, and SPI. But in the meantime I wondered if a simpler solution might be possible, a boost converter using a 555 timer. The 555 timer is a very common $0. 20 chip that can generate a PWM at a given frequency and duty cycle based on the charge time of some chosen resistors and a capacitor. The circuit would need the same basic external components as a boost converter (inductor, diode, capacitor), but it would be a lot cheaper. It wouldn`t be able to regulate the voltage, only multiply it using a calculated duty cycle, so the solution already starts off a bit limited since the voltage of a AA battery varies over it`s lifetime. But despite this limitation, there are definitely applications where providing roughly 5V from a single AA or AAA is very useful (powering servos in a kite aerial photography rig, for example) Wikipedia has a great explanation of how a boost converter works. The basic idea is that the source voltage is run through an inductor and alternately connected to ground through the transistor and disconnected so that it will charge the capacitor. The ratio...

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