Samstag, 26. Februar 2005     DIY |  studio |  mail

Sometimes you’ll need matched FETs. For a Phaser, a stereo 1176 unit.... What we need is a pair of FETs with the same electrical properties. Steffen Müller posted the following test procedure some time ago at TT. It works very good. He’s matching for cutoff voltage (Ugs). He got the tracking of both sides better than 1dB. The test board is fastly done on a breadboard. Iam using a IC socket to change the FETs. You’ll need a +15V/-15V Power Supply. If you don’t have one you could use the PSU from Jakob. It’s on the calrec Site.

1. Adjust trim until Uds drops 100mV (from 15V when FET is closed) 2. Measure some FETs and write down the values 3. In the end you’ll have (hopefully) some FETs with the same values...    ...these are your matched FETs ;-)