I need to build a boost converter (step up to 30-40V 100mA 20mA to drive a IV-18 VFD) and have found three alternatives.
Alt 1. 555 IC, Inductor, Diode and capacitor (http://www.benjscott.com/2009/07/555-boost-converter/)
I tried alt 1 this week and it worked fine. By modify the frequency on the 555 I could change step up voltage easy.
First try I got 120V from 5V
Alt2. MC34063
Bought 10 pieces of MC34063 from ebay. Never used them but should be able to work as a step up converter to 40V.
I'm not familiar with the current requirements of the VFD, but the 555 solution is only ideal if the load never varies. The MC34063 is a regulator and will provide a stable output as load as the load is within its specs.
dhenry:
You can also configure your arduino into a boost controller.
By simulating a 555 (oscillator with variable frequency) ?
If there's more about it, can you please tell a bit more?
Controller means regulating, right? Is the Arduino ADC fast enough to work in a closed loop in that area?
I tried the 555-based step up circuit last night, just to see how I got on with it using the parts I had on-hand... it worked surprisingly well! For the 555 stage I used:
R1 & R2 = 100ohms
C = 0.22uF
And for everything else:
Diode = UF4007
MOSFET = 2SK2718 (pulled from an old dot matrix printer)
L = 470uH
Setting my bench supply to 7.2V I was getting well over 700V on the output with a current draw of around 100mA, and it charged a small bank of photoflash caps very quickly Think I might build a permanent version, it's got to be useful for something!
Some people will use the 555-based boost converter for tube amplifiers so yes, it can work.
However, 7.2v -> 700v means 10% duty cycle and that may be pushing closer to the chip's limit - I think they are like 5% to 95%. Check your datasheet to be sure.
I just checked on a 555 calculator, and according to that it's 66.6% duty cycle and 21.8KHz. Oh well, it was fun to play with anyway... with a few tweaks I might be able to make something useful out of it. I quite fancy playing with an IV-18 (or similar) myself, they're cool looking tubes!