Simple DIY piezo pickup for a cello
I have a cheap cello that I can barely play. Here's how I added a pickup to it. I got this idea from another site but I forget where. You could use this on other instruments as well, there's nothing special about a cello.
I got this from either Mouser or Digikey, I forget. It's labeled MEAS-SPEC.COM, I'm sure they can help you source one. I think it was around $4.
I just used some spare audio cable and aluminum foil. Piezos have a property I don't remember learning in school: they pick up EM interference just like an electro-magnetic pickup. So they must be fully shielded.
You can put these pretty much anywhere that sounds good. I stuck it under the treble foot of the bridge. Underside of the top is another good location.