It’s not a matter of trimming away VDC. His circuit is there to be able to add a VDC to the signal, to be able to shift it up or down as desired. The soundcard won’t give you anything that is ...

A signal generator is a handy bit of kit and with the right components, it’s pretty easy to build one. Fabricating a proper signal generator probe is another matter entirely. [Frank]’s DIY ...