Charge Pump
Introduction
- For this project i decided to build a very simply charge pump using the typically hobyist materials i have on hand(Arduino,breadboard,through hole capacitors,etc.)
- So what is a charge pump any how?
- the short answer is that it is a way to raise or lower DC voltage using capacitors.
- this design also utilizes a PWM signal
- for a much more in depth answer, i recomend reading the wikipedia article on charge pumps
Design
- for this design i am mostly following this video by dave at EEVblog. check out the video for more information.
Circuit
here is the schematic of the circuit i am using.
- fairly simply schematic as you can see.
- I'm using pin 6 on the arduino for the PWM signal.
- if you take a look at the Arduino Documentation here you can see for the uno that pin 6 generates a 980 Hz. PWM signal.
- note that the blue and red lines do not connect to each other.
here is the picture of the circuit i buiilt for this project
Code
here is the code which i used for this project.
- The only thing needed was to set pin 6 to output a PWM signal.
- the arduino is nice for this, just a single line of code.on a typical 16 bit microcontroller it typically takes multiple lines of code to set everything up even for a simple PWM signal like this.
Results and Conclusions
- using a 5 volt input from the arduino i get a 12.8 volt output across the 51k resistor.
- this represents a 2.56x increase in voltage
- as you can see, using a very simple circuit one can acheive a substantial increase in voltage.
- the actual voltage output can be affected by a few factors such as the capacitance,voltage drop of diodes,frequency of PWM signal, etc.
- overall this is a interesting little circuit design which can have some practical uses.
- a typical example would be to use a charge pump to drive a LCD from a low voltage microcontroller
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