# HELP NEEDED! of stepping up a very low voltage on a circuit

Thread Starter

#### D3NCH1829

Joined Jun 30, 2022
8
In need of help on my project...

I need to speak with someone via facetime that has good knowledge of stepping up a very low voltage on a circuit board.

If someone could please contact me back it would be great

#### Papabravo

Joined Feb 24, 2006
18,806
I can help but forget about facetiming. I'm not comfortable with that level of familiarity and giving out my phone number.

Thread Starter

#### D3NCH1829

Joined Jun 30, 2022
8
I can help but forget about facetiming. I'm not comfortable with that level of familiarity and giving out my phone number.
Ok no worries,

Hey,

Thanks for helping,

I have .4 volts as constant input voltage and would like to increase to 5 to 12v if possible.

Regards,

James

I am in DC, I have most electronic components with breadboard etc.. transformers, transistors, ic..

#### Papabravo

Joined Feb 24, 2006
18,806
Ok no worries,
You are looking for a boost ratio of 5/0.4 = 12.5, or 12/0.4=30. Both of these boost ratios are well outside the normal range for simple boost converters which top out at about 6-8. At those and higher boost ratios they become very difficult to control with any degree of precision. This points us in the direction of using a transformer in either a forward or flyback configuration. If neither of those configurations are practical there are more complicated topologies, but IMHO they are not suitable projects for a novice designer in switch-mode power supplies.

What power supply voltages at what power levels will you have available on this board?

#### crutschow

Joined Mar 14, 2008
30,116
You want an energy harvesting IC such as this.

#### Papabravo

Joined Feb 24, 2006
18,806
You want an energy harvesting IC such as this.
I suppose with an absolute maximum of 4.5 Volts on Vout, that will get him close to 5V, but nowhere near 12V. It looks like a transformer is an integral part of the requirements for this circuit.

The TS has not mentioned a specific power requirement for the output voltage. The output of a harvester is likely to be underwhelming.

Thread Starter

#### D3NCH1829

Joined Jun 30, 2022
8
Unfortunately I am a rookie when it comes to circuit boards I have just started to learn and teach myself about this, watching YouTube videos etc, I have been disabled for 3 years now and am wanting to learn new things. I have most components to hand I just need help my head is aching from being so frustrated about this lol.

Again thank you for your reply

#### MrChips

Joined Oct 2, 2009
26,504
In and out voltage is only one part of the equation.
What is the output current and voltage you desire?

Thread Starter

#### D3NCH1829

Joined Jun 30, 2022
8
Yes as much as possible 12v will be great enough for what I want to achieve as I have an inverter to 240v

Regards

James

#### Halfpint786

Joined Feb 19, 2018
34
If you don't need a lot of current, check this out.

#### Papabravo

Joined Feb 24, 2006
18,806
Yes as much as possible 12v will be great enough for what I want to achieve as I have an inverter to 240v

Regards

James
What you want, if I understand correctly is to go from a source of 0.4 Volts at some unspecified power level to 12 Volts at SOME MUCH LOWER POWER level and then to your inverter to 240 VAC at some power level which will be vanishingly small. The reason your head hurts is because you are trying to do the impossible. Get you head out of the dark place it is in, and LEARN the basics of power conversion. In particular:

Power out will always be less than power in. Sometimes it will be a great deal less.

Unless you can wrap your head around this immutable rule you are doomed to an existence of abject futility.

#### MrChips

Joined Oct 2, 2009
26,504
We are still waiting to hear how much current you need at what target voltage?

Thread Starter

#### D3NCH1829

Joined Jun 30, 2022
8
Thanks for trying but that's for ac bud need dc

#### Papabravo

Joined Feb 24, 2006
18,806
Thanks for trying but that's for ac bud need dc
No Bud! You have manifestly refused to specify an output power level or current requirement. AC or DC is completely irrelevant for the time being, and you were the one who mentioned an inverter which is a DC to AC converter.

#### ScottWang

Joined Aug 23, 2012
7,244
Do you want to have a voltage converter or voltage level shifter?

Probably the voltage level shifter is easier than the voltage converter here, but it needs other power sources to supply the circuit, if you need a voltage level shifter then the 0.4V input voltage is just like the control power, when the 0.4V input and then the 5V, 12V, 240V output.

#### BobTPH

Joined Jun 5, 2013
5,248
You have also not characterized the input. You said 0.4V, but gave no current capability. Why is that important?

To boost 0.4V to 240V at 1A, which is 240 Watts, you would need 600A.

#### Papabravo

Joined Feb 24, 2006
18,806
You have also not characterized the input. You said 0.4V, but gave no current capability. Why is that important?

To boost 0.4V to 240V at 1A, which is 240 Watts, you would need 600A.
ASSUMING, you have a process with 100% efficiency. Fat chance of that.

#### Halfpint786

Joined Feb 19, 2018
34
long time ago, I asked a question about a capacitor in a high voltage circuit. I was told nobody would help me electrocute myself. Since then, I learned how to do that on my own ~ and I think this guy needs to do the same...

#### ronsimpson

Joined Oct 7, 2019
2,167
I was told nobody would help me electrocute myself.
and you are alive!

#### Halfpint786

Joined Feb 19, 2018
34
and you are alive!
Admittedly, I would have been fine. I was given my first oil burner transformer at age 10 and my first microwave transformer at 14, but yea, looking back, I appreciated the forums care for my well being for sure!

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