Quote Originally Posted by lerameur View Post
I dont know yet, but I remember some chip requires +15 and 15- supply , I only have about 6 or 7v supply.
I tried a single stage RC, with 0.2uF and 400ohms, that did not do anything..
.2uF & 400 ohm gives you an RC time constant of 12.5Khz. (.2/1000000 * 400 = .00008, 1/.00008 = 12,500)
It might work a bit better if you had a bit more cap's and a bit less resistor, say 40 ohms instead of 400, which would give you an RC time constant of 1.25Khz. And since you're trying a single stage RC filter, the roll-off would be fairly shallow, so 1.25Khz may work out fairly decent.
My suggestion...get a copy of 'The Art of Electronics'. It's one of my 'Good Books', take it with me on every trip I take, page thru it all the time. A few good sections on filters, op-amps, etc.etc.etc.