At 02:02 PM 3/18/2005, Tim Parkhurst wrote: >Hi Ian, > >So what method / equipment did you use to select and grade the transistors? I amplified the noise, recorded it to hard drive and did spectral analysis with Sound Forge. Took most of a day to get through the whole bag. :-) To grade the devices, I noted the ratio of the spectra at 10 and 100 Hz.