I’m designing and building an audio equalizer with active frequency filters for my school project and I thought the base design was completely functional until I decided to simulate it on Proteus VSM.
Turns out the circuit output doesn’t correlate with I was expecting. Analysing the circuit cautiously I found out that any potentiometer affects all the other filters and sends all their signals to ground (Or that’s what it looks like).
Circuit schematic:
Explanation:
Proteus VSM Screenshots (Blue signal is Output):
98% (Signal displays)
28% (Signal disappears)
I don’t know if the base design I'm following is wrong or the simulation is showing a mistaken output. Any advice or suggestion will be appreciated. Thanks
Best Answer
The problem is that you are trying to use a virtual ground mixer on a single-ended supply circuit.
Figure 1.
So you have two problems:
Figure 2. Adding decoupling capacitors at (1) and (2) will remove the DC from the potentiometers and allow the virtual ground (IC2D pin 13) to operate at +6 V.
Because you are using 1k potentiometers (on the low side) you'll need large capacitors at (1).