meatball envelope detector circuit

[daverdave]

Hey all, I've made a schematic for just the envelope detector part of the meatball, I was just wondering if it would work as a stand alone circuit for another application or whether I need to add or change anything. I haven't added the ldrs after the leds but obviously they would be there. It's a bit dodgily drawn as well.

[earthtonesaudio]

An input buffer would make it "play nice" with most circuits.

[daverdave]

Would it have to be a buffer splitter or just an input buffer? Cheers for the reply by the way

[GibsonGM]

Just an input buffer, I should think...a FET would work very well.  But, if you wanted to add the ability to mix in clean signal with the effected signal, you could use a splitter and switch in/out the dry signal....(try AMZ for a nice buffer-splitter schem). 

[daverdave]

what I mean is would it be better to split the signal with a buffered splitter like the amz and have one going to the detector and one going to the effect (phaser or filter etc) or could  just use a buffer then split it after into both?

[Cliff Schecht]

Something that is serving no purpose here is the first op amps 22k resistor to ground. The idea is to match the impedance seen by the - input, although that isn't the case here, so it's really serving no purpose. Bias currents are so low on any typical op amp that even a 1 meg resistor ground (where the 22k was) causes no appreciable voltage drop because the biasing requirements of the op amp are . Now, if the 22k resistor is tied to a low impedance Vbias point (4.5V or 1/2 your VCC is the standard) then its purpose is obvious.

Also, your input impedance at the first amplifier is really low. Like the others said, some sort of input buffer will prevent you from loading down previous stages.

[daverdave]

cheers, I'll try it out tomorrow.