This is the circuitof 3 band graphic equalizer using IC LF351 and few components. IC LF351 which is a wide bandwidth single JFET operational amplifier. The high input impedance of the IC makes this circuit compatible with most of the audio signal sources. The opamp is wired as an inverting amplifier. The input signal is fed to the inverting input of the opamp via the filter network. The filter network can produce a +/- 20 dB enhancement or cut on the three frequency bands 50Hz,1KHz and 10KHz.POTs R1, R2 and R3 can be used for adjusting the gain of the different bands.
Skema Rangkaian 3 band Graphic Equalizer
This Circuit can be powered from anything between 6 to 30V DC, increasing supply voltage will increase the gain and the electrolytic capacitors must be rated higher than the supply voltage.
Description IC LF351
The LF351 is JFET input operational amplifier with an internally compensated input offset voltage. The JFET input device provides wide bandwidth, low input bias currents and offset currents.
Lay out IC LF351
Features IC LF351
• Internally trimmed offset voltage: 10mV
• Low input bias current : 50pA
• Wide gain bandwidth : 4MHz
• High slew rate : 13V/μs
• High input impedance : 1012Ω
