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background I'm essentially making an mixed-signal/analog computer(to accelerate certain mathematical operations). I'm looking to create many AC filters (of different types) at low frequencies (sub 500Hz) Currents & Voltages are unimportant (I can make the voltage and current really low or really high if necessary)

the problem The problem I have been running into is that I often need HUGE capacitors(even with low voltage) and inductors(even with low currents) to get the job done. I've used active filters to solve the problem in the past, but the extra components they require usually wind up taking up the same amount of space.

(if possible) I'd like to stick with through-hole components so I can prototype, but surface mount is fine too. Higher signal integrity is preferable to low signal integrity, but I can make sacrifices.

Any ideas on what I can do to keep things small(cheap is always a plus)?

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    \$\begingroup\$ Why analog? This kind of thing is easier and smaller in a digital signal processor. \$\endgroup\$ – markrages Dec 13 '12 at 3:15
  • \$\begingroup\$ I'm using this as a learning experience to mess with mixed signals. At my job, I program FPGAs all day. I'd like to avoid coming home and programming. Also, I miss the analog stuff from school. A little more information on the circuit I am working on: I'm using tank circuits that resonate at different bandwidths in the frequency spectrum and detecting peaks to make a spectrum analyzer. There are much easier ways to do this, but this seemed fun :) \$\endgroup\$ – OhmArchitect Dec 13 '12 at 3:26
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There are simple ways to multiply the value of a capacitor if one end is connected to ground: See Capacitance Multiplier

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  • \$\begingroup\$ I've used these in the past and they are great I feel like these are highly underused circuits. They also make chips that integrate the op amp version of these (Just add capacitors and a few less resistors) They are usually sold to be used with graphic equalizers. I might look into these, but I am interested to see what other circuits stack exchange finds! Maybe someone knows a circuit that doesn't need one side connected to ground or a circuit that integrates capacitance multipliers and inductance multipliers (without just putting two side by side) \$\endgroup\$ – OhmArchitect Dec 13 '12 at 3:16
  • \$\begingroup\$ I found an example of series capacitance multiplier (sorta) falstad.com/circuit/e-capmult.html and an inductance multiplier falstad.com/circuit/e-gyrator.html anyone know a circuit that combines them both? \$\endgroup\$ – OhmArchitect Dec 13 '12 at 3:59

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