> I need help in designing a power supply with the MC34063 which will > deliver +475V @ 50mA for running a bunch of dekatrons.
Wow, that's 24 watts! A pretty beefy supply there. For that kind of voltage and power, I'd consider a transformer implementation instead of an inductor based boost converter (with or without a voltage multiplier). > Calculating the component values is not the problem as there are many > "calculators" for the MC34063 - but knowing what brands and specific > types of components to use is where I need help. > > I've been looking at Mike Moorrees' Mk 1.5 and Mk 2 designs with an > external mosfet, as I will need that to handle the power requirements. The MOSFET and inductor are the critical parts here when scaling up. Your inductor will need to pass all your output power, but with a narrow duty cycle, so you'll want your input voltage to be at the high end (18V or so), and even at DC, that's over an amp. With the narrow duty cycle for the large step-up, you'll want an inductor capable of at least ten amps or so - with a core that won't saturate at this current. You'll need a pretty low "on" resistance with your MOSFET in order to have decent efficiency at this power level, and you may end up having to parallel a few of them (in which case I'd suggest using a dedicated gate driver chip to turn 'em all on and off solidly). Your input capacitor will need to withstand a lot of ripple current, so you may end up with a few electrolytics in parallel, along with some higher-frequency types as bypass. Your wiring will have to be compact and neat, and capable of handling these kinds of currents (if it's on a printed circuit board, use thick traces and heavy copper). - John -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
