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Author Topic: Redesigning a boost converter circuit around an ATtiny85  (Read 694 times)
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South England
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The circuit in question is this: http://uzzors2k.4hv.org/index.php?page=450vboostconverter

It's well within my abilities to build it as-is (and indeed, I shall, once I've scrounged up some cores to wind the inductors), but I also have a few Tiny85's in the mail due any day now, and I was wondering if the circuit could be simplified in terms of component count by getting the 85 to do most of the work? It seems like I could make it pretty small with only one IC and for my application, the smaller the better!

The idea I had was to get the 85 to generate the switching waveform and also read the cap bank voltage through a suitable voltage divider, with a few pins left over for LED indicators (charging/ready, probably will use a bi-colour LED here). Any reason why I couldn't/shouldn't give this a shot? I reckon it'd be a good way to get used to the device and start building circuits around it. Already got the necessary Arduino cores (I think!) and have read up on programming it using a board I already have as the ISP.
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Dallas, Texas
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Yes, the 85 can replace the 555, LM311, and a few of the discrete components (those used to set the 555 frequency)--in other words the left half of the circuit.  Also, you do not need to wind an inductor.  Commercial inductors in the range specified are readily available.
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For making switching converters,buck, boost or inverting , for general use this IC MC34063 can do what you need with very few external components.
Design tool here which gives all the component values needed.
http://www.nomad.ee/micros/mc34063a/
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South England
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Thanks for the reply! As for the inductors, yeah I could buy them... but I salvaged about a mile of copper wire of varying diameters from some old CRT monitors, and have recently bought a cheap LCR meter, so that's more of an exercise than a necessity smiley-grin Keeps me out of trouble for a few hours smiley-wink
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South England
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For making switching converters,buck, boost or inverting , for general use this IC MC34063 can do what you need with very few external components.
Design tool here which gives all the component values needed.
http://www.nomad.ee/micros/mc34063a/

Thanks for the link mauried, but I think my application requires a LOT more current than that chip can handle. And I do want my caps to charge in less than a week smiley-grin I already have circuits built that can produce a few KV of p.d. but they are useless for shoving any real current around.
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