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Topic: Simple boost converter. (Read 464 times) previous topic - next topic

gonadgranny

Hi all.
Could anyone be kind enough to provide some information for how these are constructed and with which parts? i would like to incorporate a similarly simple step up converter onto my circuit. Also, if i wanted to allow for more current, how might i go about that? Many thanks,
Danny

MarkT

There is a boost-converter chip, a schottky diode, an inductor and output capacitors - not seen
a 3-pin boost converter before, no idea what chip that is.  The chip must use the output pin
to also sense output voltage on each cycle.  Wikipedia will tell you about boost converters I suspect.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

jremington

#2
Nov 10, 2017, 05:05 pm Last Edit: Nov 10, 2017, 05:05 pm by jremington
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i would like to incorporate a similarly simple step up converter onto my circuit.
Better to pay a bit more and know the complete details of what you are getting.

See Pololu's collection of boost converters. Plus, they support their products.

DVDdoug

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, if i wanted to allow for more current, how might i go about that?
Use a different part.  ;)

Note that when you step-up voltage you are stepping down the current.   ...A 100% efficient voltage-doubler requires twice the current-in as you get out.    In the real world you don't get 100% efficiency so there will be some loss of power. 

Quote
Could anyone be kind enough to provide some information for how these are constructed and with which parts?
A reliable distributor will give you the specs and sometimes a link to the manufacturer's datasheet.   You don't always get a link to the schematic or components used, but you should get complete specifications.    ...If you buy the cheapest thing you can find on eBay or Alibaba, etc., you're on your own and you take your chances.

pwillard

I strongly support the use of the pololu modules.  they are small, save time, and are affordable.

And they work nicely as well.

gonadgranny

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Better to pay a bit more and know the complete details of what you are getting.

See Pololu's collection of boost converters. Plus, they support their products.
Thank's for this, They do seem to provide schematics for some of their modules which would allow me to buy the components and incorporate onto my board which is my aim even if they're not as simple as the one i originally posted.

Quote
A reliable distributor will give you the specs and sometimes a link to the manufacturer's datasheet.   You don't always get a link to the schematic or components used, but you should get complete specifications.    ...If you buy the cheapest thing you can find on eBay or Alibaba, etc., you're on your own and you take your chances.
I really need a schematic as I only have a basic understanding of how these things work and don't have the time to learn how at the moment so making my own without one is out of the question.


I think i was just very impressed by the limited number of components of the original converter i posted and though 'hey i could totally buy those comonents and put them directly on my PCB" - i just wondered whether anyone might know exactly what they were and how they were connected together.

Thanks for the help though folks, i think those Pololu schematics are my next port of call

gonadgranny

I will purchase the TPS6120X chip required for the pololu converter. its very expensive however and i think will more likey serve as a control for how good a converter can be.
I found these IC's which are a lot more affordable. the schematic they provide does not include the values for the components, probably because they are dependent on the output voltage desired.
I don't suppose anyone would be able to 'fill in the blanks' so that i could get a 5v output from this thing could they?

MorganS

This is one of those things that looks simple in the textbook but the actual implementation is much more complex.

If you saw a diagram of a jet engine in a book, do you think you could build one from parts?
"The problem is in the code you didn't post."

MarkT

I think i was just very impressed by the limited number of components of the original converter i posted and though 'hey i could totally buy those comonents and put them directly on my PCB" - i just wondered whether anyone might know exactly what they were and how they were connected together.
I suspect the regulation performance is very limited, the lack of input capacitor will make it very noisy
electrically, and not knowing its basic performance means you're going to have to measure them to be
sure its suitable for a particular use.  The lack of a separate feedback pin means it can only be a fixed
output voltage, not programmable.

A datasheet would be good, its probably perfectly good for lots of non-critical applications, cheap and
easy to hand solder for an SMT component too.  I suspect its designed for phone-chargers.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

gonadgranny

Quote
This is one of those things that looks simple in the textbook but the actual implementation is much more complex.

If you saw a diagram of a jet engine in a book, do you think you could build one from parts?
i dont think a diagam of a jet engine would look very simple Morgan.

Quote
I suspect the regulation performance is very limited, the lack of input capacitor will make it very noisy
electrically, and not knowing its basic performance means you're going to have to measure them to be
sure its suitable for a particular use.  The lack of a separate feedback pin means it can only be a fixed
output voltage, not programmable.

A datasheet would be good, its probably perfectly good for lots of non-critical applications, cheap and
easy to hand solder for an SMT component too.  I suspect its designed for phone-chargers.
you were referring to the original converter Mark? Did you have any thoughts on this one? this one does have a feedback pin. ive bought the components and am going to try building it just to see what happens. there are a lot of cheap prebuilt variable boost converters on ebay/ alibaba which utilise this chip but i dont know how it would compare to more expensive ones...



MorganS

Sure it is. All you need is a compressor, combustor and turbine.

You can build one at home with a car turbocharger providing the compressor and turbine. A coffee can can be used as the combustor. Of course that homemade jet engine is 100% efficient at turning fuel into noise and produces no useful thrust.
"The problem is in the code you didn't post."

avr_fred

#11
Nov 12, 2017, 06:05 am Last Edit: Nov 12, 2017, 06:06 am by avr_fred
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I don't suppose anyone would be able to 'fill in the blanks' so that i could get a 5v output from this thing could they?
Well, you can always just just buy one of these and reverse engineer it. Pretty simple stuff. Set it to 5 volts and measure the pot. You'll find the output noise in these elCheap-o Chinese converters is pretty crappy. They're okay for chargers and LED's which is the target market.

Don't expect much from them and you won't be disappointed.

https://www.ebay.com/itm/MT3608-Step-Up-Power-Supply-Module-DC-DC-2V-24V-to-5-9-12-28V-2A-Boost-Converter/371044510550?hash=item5663f9eb56:g:0nsAAOSwa~BYS1uk

Cheap chip wise, another one is the SX1308, about the same specs as the 3608. They can be had for < 8 cents each in 100 pic lots on Aliexpress. The complete boards are smaller than the 3608.

gonadgranny

Quote
Sure it is. All you need is a compressor, combustor and turbine.

You can build one at home with a car turbocharger providing the compressor and turbine. A coffee can can be used as the combustor. Of course that homemade jet engine is 100% efficient at turning fuel into noise and produces no useful thrust.
I can't quite grasp the point you are trying to make here morgan although i am interested in this coffee powered jet engine.

Quote
Well, you can always just just buy one of these and reverse engineer it. Pretty simple stuff. Set it to 5 volts and measure the pot. You'll find the output noise in these elCheap-o Chinese converters is pretty crappy. They're okay for chargers and LED's which is the target market.

Don't expect much from them and you won't be disappointed.
What kind of problems can noise on the power line cause? I'll check out that other step up chip too, thanks.
All in all as long as the efficiency is fair and it can power my arduino mini reliably then i am ok. im not building cutting edge tech here.

avr_fred

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All in all as long as the efficiency is fair and it can power my arduino mini reliably then i am ok. im not building cutting edge tech here.
I have zero idea of what you are building. Using one of the Chinese boost converters at 5 volts will power an Arduino but don't expect the analog subsection to have low enough noise to function well for your (unknown) application.

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