Passive CDV-700 Speaker
This passive piezo clicker is only audible in a quiet room, as is any other passive speaker attached to a CDV-700. The CDV audio output was intended for 10k ohm wire coil headphones, but sometimes headphones get in the way. The pulse out of the CDV is about 12v.
Materials you need are a PL259 twist-on from Radio Shack [278-0191], piezo buzzer from Radio Shack [273-0059], a 3/4" PVC schedule 40 threaded plug [Nibco L17040Y or similar], a small spring that will wrap snugly around the outside of the PL259 body and a small pieze of shrink wrap tubing.
Construction
The 3/4" plug is drilled in the top with a hole large enough to pass the piezo wires. 1/16" is large enough. The body of the PL259 is inserted into the hollow of the PVC plug to check the fit. If it fits, fine, otherwise use a rotary tool to remove just enough material for a snug fit. If the fit is slack originally, when the final assembly is made, some Gorilla Glue is squeezed around the body of the PL259 and will foam up to fill the gaps.
The PL259 center tip is shortened *just* enough that it will fit snug when screwed down over your CDV audio plug. A rotary tool with a cutoff wheel will do for shortening the tip. Cut off the mounting wings of the piezo with the same rotary tool to make the piezo round.
The small spring is wrapped around the body of the PL259 to provide a secure negative connection. The wires of the piezo are inserted through the top of the pvc plug and the black wire slipped under the spring and soldered to it. The red wire goes inside the PL259 center pin from the inside and is soldered to that.
Before sealing it up, attach the assembly to your CDV and check to make sure it clicks. If it works, then press the PL259 into the PVC plug [with Gorilla Glue if needed] and shrink wrap over the assembly.