I am having a bit of trouble trying to simulate a variation(different frequency ranges/gain for the BP filters) of this project: https://makezine.com/projects/audio-spectrum-analyzer/ I am not too experience in simulation so I am not too sure what I'm missing to get the simulation to work. I'm using multisim. Here is one of the bandpass filters that has the frequency ranges of 20-250hz. Also what exactly is the purpose of c3 and r5? I circled them. All help appreciated thanks!
You have supply pins connected to U2 and U3 but you've forgotten to connect them to U1.
C3 smooths the rectified voltage from the emitter of the BJT. In other words it's a cheap and inaccurate signal peak detector with C3 as the hold capacitor (go google this). R5 is needed by the BJT and also offers a discharge path for C3 in order to allow dynamic signals to refresh the display. If it wasn't there you'd have a peak-hold circuit.