Boosting 0.3V to 2V or higher?

[Artlav]

Hello.

I want to get about 2-5 volt out of a 0.3V DC source, at µA levels, or get power out of it in any other way that would allow to charge a capacitor up to the said 5V.
Any leads on how can this be done?

 

[goldsmith]

Dear Artlav
Hi
As i understood you want give a 0.v to a circuit and get 2-5 volts and with low current ?i think it will be a bit difficult . before that , tell , me that how much current can give that 0.3 v DC ? is that limited ?
Best Wishes
Goldsmith

 

[D.A.(Tony)Stewart]

A transimpedance amplifier may be what you want!
Otherwise it is simply Ohm's Law. Change the load resistance. 5v/1µA = 1MΩ

 

[godfreyl]

Perhaps a JFET oscillator could be used. The output can be stepped up and rectified.

A JFET is the only active device I know that can work with such a low supply voltage.

 

[Artlav]

A transimpedance amplifier may be what you want!
Otherwise it is simply Ohm's Law. Change the load resistance. 5v/1µA = 1MΩ

The idea is to harvest ambient energy and store it for later bulk use.
So the 0.3V source is the only power source there is, nothing to amplify with.

As i understood you want give a 0.3v to a circuit and get 2-5 volts and with low current ?i think it will be a bit difficult . before that , tell , me that how much current can give that 0.3 v DC ? is that limited ?

Pretty much.
The current at the source is in the 50µA-1mA range.
At the output i want to see a charged capacitor or battery - 5V would be about perfect, 2V sufficient.

 

[goldsmith]

Use an AD620 ( instrumentation amplifier ) to amplify it , simply !

 

[D.A.(Tony)Stewart]

No good. You cant harvest potatoes from a peanut farm.

 

[goldsmith]

What do you mean by that ?

 

[dselec]

he means u cant use amp cause amp needs supply and he does not have any.
anyway he can use multiple cells or try making a Germanium transistor oscillator.

 

[goldsmith]

Dear dselec
Hi
Yes , i forgot it ! without supply , i think it is impossible , because his maximum current is pretty low , ( maximum current that 0.3 v can prepare ) . isn't it ?
Best Regards
Goldsmith

 

[Kripton2035]

microchip mcp1640 can do it, but from a minimum of 0.65v which is already quite a small voltage value...
I don't think you can do it with 0.3v because you cannot power any silicon device with it, you need at least 0.6v
can you put two sources of 0.3v to get the 0.6v needed ?

 

[godfreyl]

I don't think you can do it with 0.3v because you cannot power any silicon device with it, you need at least 0.6v

See my previous post. A JFET will work with 0.3V.

 

[dselec]

germanium will work for 0.15v
which fet will work ?

 

[mtwieg]

Linear tech makes an energy harvesting IC that can do what you need. Check out the LTC3108. As godfreyl suggests it uses a JFET oscillator and transformer to operate from voltages as low as 20mV, and can give a Vout of 5V.

 

[Artlav]

Ok, started trying the JFET oscillator idea.
I never worked with JFETs before.

n-JFET (J310), and a 23:1 transformer wound around a toroid.

It works from an AA battery, producing 20kHz oscillations peaking at 40V, but does not work at all from 0.3V.
Is that the right kind of oscillator?

can you put two sources of 0.3v to get the 0.6v needed ?

I can, but i can also just use a battery, so i assume i can not.

Germanium transistor oscillator
...
germanium will work for 0.15v

Germanium transistors are not listed separately, nor are they searchable by minimal voltage.
Any references?

Linear tech makes an energy harvesting IC that can do what you need. Check out the LTC3108. As godfreyl suggests it uses a JFET oscillator and transformer to operate from voltages as low as 20mV, and can give a Vout of 5V.

Sounds good, but not a solution for the moment - i'm more interested in implementation than capability.

 

[FvM]

germanium will work for 0.15v
which fet will work ?

The said "energy harvesting" DC/DC converter uses a depletion mode FET oscillator. Besides JFETs, that are always depletion mode, there are also depletion mode MOSFETs. LTC 3108 is however designed for sources like thermoelectric generators, that have a relative low impedance.

A DC/DC converter for a source with higher impedance should be taylored to the source parameters. Before starting an actual design, I would do a hand calculation of expectable current and power levels. I presume, that everyone is aware of conservation of energy laws...

P.S.: I see, you did some experiments in the meantime.

It works from an AA battery, producing 20kHz oscillations peaking at 40V, but does not work at all from 0.3V.
Is that the right kind of oscillator?

That's basically the right kind of oscillator. There are however additional operation conditions for the relation of FET gm, energy source impedance and transformer inductance. You have to figure it out.

 

[godfreyl]

It works from an AA battery, producing 20kHz oscillations peaking at 40V, but does not work at all from 0.3V.
Is that the right kind of oscillator?

Try swapping the transformer primary and secondary. At such low voltages, the JFET behaves like a triode with very low gain. When I played with a similar circuit in a simulator, I needed a step-up ratio of 10:1 from drain to gate to get it to work.

 

[D.A.(Tony)Stewart]

did the conceptual question change?
I thought the power source was limited to "µA levels"

In theory if it were such a source such as a solar cell on a dim day.... the µA levels of current would integrate to any voltage limited by leakage resistance.

But if we are talking uA power source at 0.2V .. I think we are talking about peanut size power levels, when others are offer potato size solutions.

 

[godfreyl]

Sometimes all you have is one peanut, and you need to make the most of it.

 

[jreynolds09]

not sure but a joule thief may help you with this as it can take .3-.5v and run a 3v led. Just a thought. I'm new to electronics though so I would research it before taking my advice.