yes, I actually have complete control over everything. My idea is to = drive 3 LEDs in diferent frequencies and then measure them with a = photodiode. The photodiode response would be a DC level for ambient = light plus the 3 frequencies of the LEDs. So I would cut off the DC = voltage and measure the amplitude of each frequency. These amplitudes = would be how much the LED is affecting the photodiode. Cheers, Bruno Bruno L. Albrecht Eng. da Computa=E7=E3o/06 Falker Automa=E7=E3o Agr=EDcola Ltda. http://www.falker.com.br YES NOPE9 escreveu: > I was amazed that MC1496s were still being sold at DigiKey ( ON = > Semiconductor ). > I had a lot of fun with them in the past. Using the MC1496 seems = > harder than using > a switched capacitor filter. Do you have the 3 frequencies available ? > Gus > > = >> On Dec 9, 2009, at 4:22 AM, Bruno L. Albrecht wrote: >> >> I'm thinking about using a MC1496 (Balanced Modulator / = >> Demodulator). It >> seems to fit my needs, once I can sum the carrier to an on/off = >> switch, and >> then just demodulate the signal with the same carrier. And all of it = >> with >> only two cheap IC per frequency! >> What are your opinions? >> >> Cheers, >> Bruno >> >> On Thu, Dec 3, 2009 at 4:39 PM, Peter Restall = >> wrote: >> >> = >>> On Wed, 2 Dec 2009 17:51:34 -0200, Bruno L. Albrecht wrote: >>> >>> = >>>> Hi, >>>> I'm trying to separate 3 frequency components from an analog = >>>> signal. The >>>> original signal is composed by the sum of 3 frequencies (1500, = >>>> 4000 and >>>> 10200 Hz) and some noise. The objective is to separate only those 3 >>>> frequencies and evaluate their magnitudes. I thought about lots of = >>>> ways >>>> = >>> of >>> = >>>> doing it, but couldn't get an effective one. >>>> Any ideas? >>>> >>>> Cheers, >>>> Bruno >>>> >>>> = -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist