Electronics > Beginners
Question About Boss GE7 Schematic
(1/3) > >>
eev_carl:
Hi,

IC1, IC2, and IC3 in this schematic look like Sallen-Key High Pass Filters.  I had expected to see band pass filters since the schematic is for a 7-band eq.  Is this the correct analysis (boosting / cutting HPFs rather than band pass filters) or is there an LPF part that I'm missing?

Thanks,
Carl

https://www.hobby-hour.com/electronics/s/ge7-equalizer.php

RyanT:
Near the bottom of the page, they're listed as TL022CP dual op-amps, and the schematic looks to me like the standard arrangement with 2 channels per IC, for channels 1&2, 3&4, and 5&6.
eev_carl:

--- Quote from: RyanT on October 27, 2018, 09:39:25 pm ---Near the bottom of the page, they're listed as TL022CP dual op-amps
--- End quote ---


I'm asking about the Sallen-Key high pass filters (which includes the op amps).  I thought each potentiometer would cut or boost a band (band pass filter) but I don't see an LPF paired with each frequency midpoint.
RyanT:

--- Quote from: eev_carl on October 27, 2018, 09:44:05 pm ---I'm asking about the Sallen-Key high pass filters (which includes the op amps).  I thought each potentiometer would cut or boost a band (band pass filter) but I don't see an LPF paired with each frequency midpoint.

--- End quote ---
Sorry, I misunderstood what you were asking. You are right that S-K can be configured as a band pass filter, but your schematic looks more like a multiple feedback BPF, although it has been a decade or two since I've done this kind of filtering, so I'm sure someone will set me straight if I'm wrong here.
Andy Watson:
IC1-3 are gyrators - essentially negative/reverse impedance converter that make capacitors C3, C6, C8, C13, C14 and C15 look like inductors - in the sense that their impedance appears to increase with increase in frequency.

Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod