I've been working on a handheld messager, and I require 3.3v to power the Arduino and its other components. After some research, I found this tiny board, which claims to be a buck/boost converter (input 1.8-5v, out 3.3v), but there does not seem to be any coil of any sorts. Is this even possible, or is this bogus?

3.3v buck/boost converter
https://www.aliexpress.com/item/5pc...bd25-42ac-9c04-a48b4891f55c&priceBeautifyAB=3

Thanks in advance,

Shre

 

It's a charge pump which uses capacitors to change the voltage.
They generally work well only for currents of a few tens of mA or less.

 

It's a charge pump which uses capacitors to change the voltage.
They generally work well only for currents of a few tens of mA or less.

I'm unfamiliar with this, but presumably uses a series/parallel switching scheme to charge and discharge the cap's and achieve a higher secondary (D.C.)voltage. Seems pretty simple. Certainly this can be constructed to handle larger currents.

 

The ad doesn't mention the current capability, I guess they figure they will sell more this way?
Don't expect much.

 

Certainly this can be constructed to handle larger currents.

Yes, it's just that the capacitor size gets very large.

 

If you are looking for information about this type of circuit, another name for it is "flying capacitor" charge pump.

 

I've been working on a handheld messager, and I require 3.3v to power the Arduino and its other components. After some research, I found this tiny board, which claims to be a buck/boost converter (input 1.8-5v, out 3.3v), but there does not seem to be any coil of any sorts. Is this even possible, or is this bogus?
It is also possible that the package has a very small inductor because it runs at a very high frequency. But there are ways to double the voltage without an inductance, so it probably does work. BUT certainly you also need to know the current that your application requires. That is very important.
3.3v buck/boost converter
https://www.aliexpress.com/item/5pc...bd25-42ac-9c04-a48b4891f55c&priceBeautifyAB=3

Thanks in advance,

Shre

 

RE: ""How can it be possible""
https://en.wikipedia.org/wiki/Charge_pump
Me is not seeing any coil there too...

 

I've been working on a handheld messager, and I require 3.3v to power the Arduino and its other components. After some research, I found this tiny board, which claims to be a buck/boost converter (input 1.8-5v, out 3.3v), but there does not seem to be any coil of any sorts. Is this even possible, or is this bogus?

3.3v buck/boost converter
https://www.aliexpress.com/item/5pc...bd25-42ac-9c04-a48b4891f55c&priceBeautifyAB=3

Thanks in advance,

Shre

Yes, stepping up voltages without an inductor is possible, often done with a charge pump arrangement. You can find lots of information about them, and in addition the major suppliers sell them. But you can also buy devices with a much bigger capacity in small packages from the same supplier, and those have regulated output voltages. So there are a lot of ways to provide the voltage that you need.

 

It's a charge pump which uses capacitors to change the voltage.
They generally work well only for currents of a few tens of mA or less.

Which can be cascaded to make a Cockroft Walton voltage multiplier. You can get decent current by driving it with high frequency - cant remember the total current for all 3 guns on a colour CRT, but its not to be sniffed at. Not in the same league as a microwave oven - but that also uses a charge pump voltage doubling rectifier.

There's also such thing as a piezo transformer - but its high impedance leaves it with few practical applications.

 

Which can be cascaded to make a Cockroft Walton voltage multiplier. You can get decent current by driving it with high frequency - cant remember the total current for all 3 guns on a colour CRT, but its not to be sniffed at. Not in the same league as a microwave oven - but that also uses a charge pump voltage doubling rectifier.

There's also such thing as a piezo transformer - but its high impedance leaves it with few practical applications.

Actually, in thinking about this application, what makes sense would be to use two 1.5 volts cells in series. Then there would be no need for a voltage changer, and hence greater efficiency. AND it would be less expensive as well. That 3.3 volts is not a magic number, but rather what they want to use instead of 5 volts. So since it is an arduino toy the big deal would be to not exceed the upper supply voltage limit.