On a Samson C01U USB mic, I add a 1/4” mono TS jack. I soldered the two wires, one for tip, the other for sleeve ground on the board closest to diaphragm( head of mic). The larger board is the Analog to Digital converter. It was a while ago, but I know I made sure connection was made to send wire (yellow I remember) and not to voltage coming up from larger board. The TS jack and cord is about five feet. I usually plug into my guitar pickup so can sing into mic with guitar and into PC for recording. But, I also plug the 1/4” jack into my mixer, but still must keep usb plugged into computer for power, then the analog signal from mic diverts to TR jack to mixer allowing use as analog condenser mic. This is what you are aiming for. A 5v cell phone charger cannot be used to supply power to mic. Chargers only bring the 5v to pin one, while PC USB port must send power on other pins to activate the mic.
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