What IC will I need to accomplish this?

[wannaBinventor]

I'm tinkering with making a little generator out of a PC fan. Some guys on another forum are giving me some advice on that end, but I'm wondering how to pair that up with an IC to actually harvest the energy.

At low wind speeds (probably all I'll get around here) I'm getting 1.4 volts AC with the present, un-modified fan and just soldering directly to the coil leads.

I'd ultimately like to use that power to drive a µC and an RF transmitter - with a low duty cycle (putting both to sleep for a couple of minutes, waking it up just long enough to take a reading and transmit, and then putting it back to sleep).

I need an IC that will take the AC voltage of 1.4 RMS (hopefully a few more mV once I tweak the "generator"), store the energy, boost the output to at least 3.0 volts, and let me draw from it at random times based on when I wake up my µC and rf tx. Together, these will draw about 20mA when transmitting -- then back to sleep.

Is there an IC that is made for this (IE, no external battery), or do I just need to rectify the AC to DC, multiply it, and charge a rechargeable battery?

As a side note, I'm not interesting in using a bigger generator -- I'd like to make it work given the current constraints.

Thanks!

 

[cobra1]

wind generator---Rectifier ---super capacitor---joule theif (boost voltage to 3v ish) ---application.

i have also got a pdf somewhere with a really good joule theif type circuit

 

[crutschow]

How long do you need the circuit to operate if the wind stops?

How much current can you draw from the fan at 1.4V? You need to test the fan with a load.

Another simple circuit to increase the voltage is the Black Regulator.

 

[blueroomelectronics]

A computer fan is a very poor wind generator.