The small-
circuit project illustrates a switch mode power supply (SMPS) that boosts low voltage to the high voltage require to drive nixie tubes while being operated on batteries or low voltage wall-warts.
The
Microchip Application Note TB053 is used as the basis of this design with several modifications which outlines the basic principle behind the SMPS. A charge is allowed to build in the inductor by a FET grounded by a microcontroller. The charge flows through the diode going to capacitor when the FET is turned off. The high voltage can be monitored by the microcontroller as permitted by a voltage divider feedback. The desired voltage can be maintained if needed by activating the FET.
Power Supply Tubes Circuit
The Microchip application note begins by determining the required power and then chooses an inductor charge time without concern for available inductors. The amount of time it takes the current to flow out of inductor can be determined with an equation but in practice, this time is very short.
A
microcontroller is used to drive the SMPS using the hardware pulse width modulator of a PIC. The 8-pin PIC12F683 is chosen for this project.