Electronics > Projects, Designs, and Technical Stuff
Need help with power rating for active equalizer components
hummusdude:
I'm building this 5 band active EQ for my home hi fi. I'm putting together a PCB and because I'm making it stereo there are a lot of passive components. Although I have minimal experience using SMD parts I starting thinking this may be the way to go to keep the size of the board from getting too big. But then it occurred to me that since this isn't a strict logic circuit that the power rating could be a factor. I'm comfortable with small circuit analysis but this one is quite complex for my experience. I'm not at all confident I could figure out the max power draw, or potential current hot spots that need a little more capacity. Is there a rule of thumb for this sort of circuit?
dmendesf:
Your ICs will consume like 10mA each, not a big deal. You can use 0603 resistors and capacitors. Large value capacitors may be better served by 0805 size.
jdthorpe:
So, it looks like the Vs+ and Vs- for the opamps are left out (for brevity), but one thing I think might
be an error is highlighted in in green in the attached schema. My read is that the highlighted node should not be
connected, but I'm a total noob so I'd be equally happy to find out that I'm wrong
hummusdude:
Great observation. I have to agree it seem odd that the virtual ground would be tied to the output of the input buffer.
hummusdude:
Also wondering if it's necessary to keep signal ground and power ground separate in a low power circuit like this. I know it's good practice on a power amp to prevent ground loop hum issues, but this is very low gain so not sure if that matters. The person who made the schematic seems to have gone out of his way to show signal ground and power ground as separate.
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