# Is there any way to invert low voltage AC to higher voltage DC?

#### JCP

Mar 7, 2023
6
Hello, I've been finding ways and it seems that some posts about this has been very hard for me to comprehend nor replicate. We have this project going on and mine tackles about somehow acquiring <250mV and it should be stored in 3.7V lithium Ion Battery. For it to be stored, 5V for input should be met (as far as I have understood it), can you help me in converting this <250mV of AC to higher voltage DC (preferably 5V)? Your help would be very much appreciated.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,719
Drawing erngy from a source as low as 250 mV or less is not a simple task. Look up "energy harvesting" - complete integrated circuits are available.

Feb 19, 2021
767
How much current do you need at 5V ? The AC input, what frequency is it ?

Regards, Dana.

#### JCP

Mar 7, 2023
6
Thank you for the immediate response, the needed frequency would be between 1 to 1.5 amperes.
How much current do you need at 5V ? The AC input, what frequency is it ?

Regards, Dana.

#### JCP

Mar 7, 2023
6
Will definitely check it out, thank you very much!
Drawing erngy from a source as low as 250 mV or less is not a simple task. Look up "energy harvesting" - complete integrated circuits are available

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,719
needed frequency would be between 1 to 1.5 amperes.
Frequency is in Hz. You give the amperes only.

1 A to 1.5 A at 5 V is equivalent to 20 A to 30 A from a 250 mV source. This is very unusual. What kind of source is this?

#### JCP

Mar 7, 2023
6
Frequency is in Hz. You give the amperes only.

1 A to 1.5 A at 5 V is equivalent to 20 A to 30 A from a 250 mV source. This is very unusual. What kind of source is this?
We're trying to explore more about energy harvest and storage as students that find potentiality in the utilization of microphone transducers as sources.

#### JCP

Mar 7, 2023
6
Drawing erngy from a source as low as 250 mV or less is not a simple task. Look up "energy harvesting" - complete integrated circuits are available.
Oh, I think I've expressed it incorrectly. My project is about harvesting energy using a microphone transducer; in my findings, a 107 db of sound produced in close contact to the transducer produced 1.735 volts in 1 second. So as to widen its scope, I have decided to improve it's sensitivity to noise, in a way that it gets sound energy from the surroundings, not just produced in close contact to the transducer. Now, I have acquired 4 transducers, connected in a parallel circuit, into a full wave bridge rectifier, and a 220 uf capacitor. Thereafter, for about a minute of shouting and producing noise into the transducers directly, I have acquired less than 280mV DC. Is there any way I can boost it further to 5V to charge a Lithium Ion Battery?

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,719
You need special energy harvesting ICs. 280 mV is very low, below the threshold voltages of BJTs or MOSFETS. These energy harvesting ICs have special components taht can work at low voltages.

JCP

#### Alec_t

Jul 7, 2015
3,590
Shouting into a microphone isn't going to have anywhere near enough energy to charge a Li_ion battery (other than a microscopic one) in any reasonable time . Current and voltage are both important. For a given amount of input energy, raising the voltage will be at the expense of lowering the current.

#### crutschow

May 7, 2021
848
You will find it quite difficult to get a useable amount of energy from a microphone, as the energy generated from a typical one is very tiny.

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,719
connected in a parallel circuit, into a full wave bridge rectifier, and a 220 uf capacitor.
Use Schottky diodes for the rectifier. This will reduce the losses in the rectifier, leaving more energy to be harvested.

Energy harvesting is generally used for very low energy requirements only, see posts #10 and #11.

JCP

#### JCP

Mar 7, 2023
6
Th
Use Schottky diodes for the rectifier. This will reduce the losses in the rectifier, leaving more energy to be harvested.

Energy harvesting is generally used for very low energy requirements only, see posts #10 and #11.
Thank youu, I'll update about the results soon

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