In order to power the motors on my robot, I need a source of 12 V. My first source of power was a 12 V sealed lead acid battery. Although these batteries are very good at providing a stable source of voltage for the amount of current I required for my use (between 500 mA to 1 A), there were two disadvantage with this battery type: they are heavy and they require a special charger that I find hard to come by.
To reduce the weight of my robot, I decided to replace the sealed lead acid battery with a voltage stepper circuit. National makes some nice integrated circuits that can be used for this purpose (LM2587). If you go on there Web site, you can use a design tool (Webench) to build a custom circuit based on your requirements. Here is the circuit that is recommended for stepping between 4 V to 6 V up to 12V (maximum 1 A current):
Voltage Stepper Circuit
Parts List for Voltage Stepper
|Cin||100 uF electrolytic capacitor|
|Cout||180 uF electrolytic capacitor|
|D1||International Rectifier 6CWQ03FM (VFlatlo = 0.45 V)|
|Rfb1||1500 ohms resistance|
|Rfb2||13300 ohms resistance|
|Rcomp||2940 ohms resistance|
|L1||15 uH inductor (DCR = 0.027 ohms)|
|Ccomp||1 uF ceramic capacitor|
|Cinx||0.1 uF ceramic capacitor|
Here is my implementation of this circuit:
To contact me, send an email to: firstname.lastname@example.org.
Last updated: December 20, 2002