Prev: ADC techniques, was Re: Diode-Connected Transistors
Next: Totally O/T: what was that system called?
From: markp on 26 Jul 2010 11:44

"Paul Keinanen" <keinanen(a)sci.fi> wrote in message
news:b9qo46dkgr3vc729b44q7004al9k2qgodn(a)4ax.com...
> On Sun, 25 Jul 2010 17:07:54 +0100, "markp" <map.nospam(a)f2s.com>
> wrote:
>
>>>
>>> markp wrote:
>>>
>>> Hey mark, I have already looked at the LTC3108 chip.yes it's used for
>>> energy harvesting, but it needs a dc input voltage. I plan to use that
>>> chip, but before that I have to rectify my AC voltage.
>>>
>>
>>Not true, the application circuit actually produces an AC source from DC
>>by
>>using a resonant oscillator which is then synchronously rectified. The
>>device can be used with AC, see page 14: "Any source whose peak voltage
>>exceeds 2.5V AC or 5V DC can be connected to the C1 input through a
>>current-limiting resistor where it will be rectified/peak detected." In
>>fact
>>it mentions vibrational sensors as a possible input source which is very
>>likely to be AC.
>>
>>So it seems by placing a 1:12.5 step-up transformer from your 200mV input
>>you could produce a 2.5V AC signal suitable for use.
>>
>>Mark.
>>
>
> Apparently the internal oscillator is operated at 10-100 kHz, so it
> would make sense to optimize the synchronous rectifier for that
> frequency range too.
>
> I very much doubt that the synchronous rectifier would be too useful
> at 950 MHz, which the OP had in mind.
>
>

Yes, 950MHz is going to be probematical. I didn't see the 950MHz reply
before I wrote this, but the OP seemed to think the chip wouldn't work with
AC signals at all but it does.

Mark.


From: Nik on 26 Jul 2010 12:08
Could you feed this signal to a hi-Q tuned circuit and draw Volts from that
??

I've seen something like this done with a 'tank' circuit tuned to a
powerful local transmitter being tapped and rectified to provide Vcc for a
flea-power one-transistor 'amplified crystal-set' receiver tuned to a
weaker station...

---------------------------------------
Posted through http://www.Electronics-Related.com
From: markp on 26 Jul 2010 12:36

"markp" <map.nospam(a)f2s.com> wrote in message
news:8b5obbFq0uU1(a)mid.individual.net...
>
> "Paul Keinanen" <keinanen(a)sci.fi> wrote in message
> news:b9qo46dkgr3vc729b44q7004al9k2qgodn(a)4ax.com...
>> On Sun, 25 Jul 2010 17:07:54 +0100, "markp" <map.nospam(a)f2s.com>
>> wrote:
>>
>>>>
>>>> markp wrote:
>>>>
>>>> Hey mark, I have already looked at the LTC3108 chip.yes it's used for
>>>> energy harvesting, but it needs a dc input voltage. I plan to use that
>>>> chip, but before that I have to rectify my AC voltage.
>>>>
>>>
>>>Not true, the application circuit actually produces an AC source from DC
>>>by
>>>using a resonant oscillator which is then synchronously rectified. The
>>>device can be used with AC, see page 14: "Any source whose peak voltage
>>>exceeds 2.5V AC or 5V DC can be connected to the C1 input through a
>>>current-limiting resistor where it will be rectified/peak detected." In
>>>fact
>>>it mentions vibrational sensors as a possible input source which is very
>>>likely to be AC.
>>>
>>>So it seems by placing a 1:12.5 step-up transformer from your 200mV input
>>>you could produce a 2.5V AC signal suitable for use.
>>>
>>>Mark.
>>>
>>
>> Apparently the internal oscillator is operated at 10-100 kHz, so it
>> would make sense to optimize the synchronous rectifier for that
>> frequency range too.
>>
>> I very much doubt that the synchronous rectifier would be too useful
>> at 950 MHz, which the OP had in mind.
>>
>>
>
> Yes, 950MHz is going to be probematical. I didn't see the 950MHz reply
> before I wrote this, but the OP seemed to think the chip wouldn't work
> with AC signals at all but it does.
>
> Mark.

Maybe putting one of these RF harvesters at the front end might help:
www.powercastco.com/PDF/P2110-datasheet.pdf

Mark.


First  |  Prev  | 
Pages: 1 2 3 4 5
Prev: ADC techniques, was Re: Diode-Connected Transistors
Next: Totally O/T: what was that system called?