On Tuesday 03 April 2007 02:41, Ramakrishnan Muthukrishnan wrote: > On 4/3/07, al davis <[EMAIL PROTECTED]> wrote: > > If you look at the designs of older ones, you will see that > > they did it with 2 or 3 tubes. The basic design can be > > updated to use today's components, with significantly > > improved performance. > > Wes Hayward's book EMRFD has some designs. > > > Another one that could be useful is a "Q-meter". It is > > used for measuring inductors and capacitors by resonance. > > I started designing a small LC meter using an AVR > microcontroller. Stalled because of lack of time. Have to > revisit.
I mean a good old-fashioned one that is completely analog. There is an oscillator, then an amplifier driving the "circuit under test" in parallel with a variable capacitor. You adjust the variable capacitor to peak or dip, I forgot which. The good old resonance formula tells you the inductance. The meter tells you the Q. I still have one. Based on the kind of tubes in it I think it was made about 1940. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user