'RF bias' microphones can provide an effective alternative to the use of conventional high impedance condenser microphones, in situations where moisture can be a concern (outdoors - high humidity environments, etc).
Their design uses much lower impedance circuitry for capsule control, and that can help alleviate noise problems which may occur when using conventional condenser microphones in outdoor locations....
More details on the concept HERE
Currently, it is believed that only Sennheiser and Rode utilise this concept commercially - and the microphones using this approach tend to be expensive devices.
Until now there seems to have been very little use of the concept in the DIY hobby world of microphone building, with inductor details seemingly a stumbling block to the design of any hobby mics.
This project is an attempt to correct that, by presenting a simple DIY RF biased condenser microphone, using inductors created from 'off the shelf' IF transformer blanks ...
You can find inductor construction details, including source suggestions for the transformer 'blanks'
HERE
This project resulted from a request at the start of THIS THREAD on the 'Group DIY' forum.
My thanks to all those who have contributed to the 600+ posts now in that thread... To Gerard, the thread starter - to Ruud for his prototype PCB layout - to Ricardo and Abbey for their expert suggestions - and especially to Khron for his expertise and patience in designing the various versions of the final project PCB... All helped to drive the project forward - again, my thanks.
• To see the project details, just click on any of the headings below - or at the top of the page •