Does anyone know a project to build a DIY microphone for video recordings? i wanna record classroom sessions and thinking about some sort of small box with transmitter, battery and mic in them to hang around the speakers neck. It doesn’t have to be hidden. ease of use and low price with good sound quality are the main objectives.
Professional equipment, like from Sennheiser tends to be too expensive for a non commercial user.
It is pretty trivial to add a mic to one of the (analog, not digital, and probably FM) transmitters or transmitter/receiver pairs @Sparkfun. The NS73 (get the one on the breakout board!) is a good choice. The little programmable transmitter can be picked up by a standard radio and the audio out jack of said radio can go to a recorder.
If you wish to go pre-made, have you looked at Lightspeed? They have RF & IR systems.
http://www.lightspeed-tek.com/
Are you the speaker, or have you confirmed that the speaker is willing to wear such a device? Have you considered that students may be reluctant to speak if they know they may get recorded?