Post Number: 116
Votes: 0 (Vote!)
|Posted on Thursday, 31 October, 2013 - 01:20 am: ||
Copy of my post to LTspice group for possible interest of some readers;
Now well into old age, a hand tremor stops me from making good solder joints, so I moved from actual assembly of small circuits to virtual electronics using LTspice. The experience was both educational and satisfying so I offer my lasting thanks to the LTspice team for publishing a design tool which also serves as diversional therapy for the aged and infirm.
I started with a return visit to parallel LCR resonance, the simplest of circuits having only one mesh and no branches. Components were set for resonance at 1.59 MHz and a Q of 5. The aim was to compare these settings with observations of Fres and Q taken from both the the displayed sharpness of the resonance curve and the decrement of the damped sinusoid following a 1 microsecond impulse. The latter gave a sensibly accurate result but Q readings derived from the (relatively gentle slopes of the) resonance curve were scattered up to 10 percent of nominal. Probable cause was faulty observation since the circuit was voltage-fed so the resonance curve would have been symmetrical.
My next effort will logically be a return to mesh analysis comparing my pye--delta transforms against the displayed values of AC in each mesh of a Wheatstone bridge circuit, thence onward to op amps and Sallen-Key filters.
Again my thanks to all concerned and especially to the American college student who published a version which runs on my Mac lap-top. Future posts will be restricted to those likely to excite interest.