Hello Folks!
I would like to generate a 12V output at 30mA from a 3V-4.2V input.
This is what i would like to power with that:
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It is a pin diode based radiation detector, ever since i found that site i wanted to build one.
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I guess the only option is a DCDC converter, but the routing, inductor and diode selection to get a stable and clean output is a bit out of my league i think.
I could buy a pre made DCDC-Module but i would like to build/route the whole circuit myself.
What would be your recommendation?
Greetings,
Peter
Why not just buy one of the pre-made LM2577 booster from eBay, $1 to $2 dollars.
If you insist on making one and found the LM2577 a bit too difficult, try the MC34063 based boost.
If you have an old CLA (cigarette lighter Adapter plug for cars) phone charger that you don't need, chances are, you will find one of those 34063 running it in buck mode. It has all the parts you need to convert to boost - except a capacitor or two and a resistor or two or a trimpot. You may even be able to do it on the same PCB. Cut a few traces, rewire it a bit (see the 34063 datasheet), swap the fixed voltage divider feedback sense to use a trimpot, and you are off and running with an adjustable boost.
Typically, the output capacitor will be too low since it likely bucks 12V down to 5V, so you would likely find a low (10V-ish) rated output capacitor. You need to change that to at least 16V. Swapping the input and output capacitor in your case would work. The original input capacitor should be at least 16V. You wont get the cleanest of power, and most efficient of boost, but it should work.
Check the 34063 datasheet, you will see the traces to cut and modify is not that many. If all you need is just 30mA, 34063 works rather nicely.
Good luck, and have fun. I made a few doing exactly that, and it was fun.