Sorry if this is a repost, I didn't see my first post.
I'm looking for constructive criticism to create a better model and help me with the concept I present about the stray capacitance.
The concept: the stray capacitance doesn't lower the input impedance it just adds to the resonating capacitor, changing the resonant frequency. The 100meg is supposed to isolate the power supply. (normally very loose inductive coupling is used) The 950K is just to provide a voltage divider to show me the input impedance. The experiment then removes the the 950k and places a 4pf stray capacitance to ground. Thanks, Mikek
Version 4 SHEET 1 1100 680 WIRE -192 112 -288 112 WIRE -80 112 -112 112 WIRE 0 112 -80 112 WIRE 80 112 0 112 WIRE 320 112 160 112 WIRE 448 112 384 112 WIRE 544 112 448 112 WIRE -288 128 -288 112 WIRE -80 128 -80 112 WIRE 0 128 0 112 WIRE 448 144 448 112 WIRE 544 144 544 112 WIRE -288 224 -288 208 WIRE -80 224 -80 208 WIRE -32 224 -80 224 WIRE 0 224 0 192 WIRE 0 224 -32 224 WIRE 544 224 544 208 WIRE -32 240 -32 224 FLAG -288 224 0 FLAG 544 224 0 FLAG 448 224 0 FLAG -32 240 0 FLAG 256 288 0 SYMBOL voltage -288 112 R0 WINDOW 123 24 124 Left 2 WINDOW 39 0 0 Left 2 SYMATTR Value2 AC 4 SYMATTR InstName V1 SYMATTR Value SINE(0 20 1e6) SYMBOL cap 528 144 R0 SYMATTR InstName C2 SYMATTR Value 4.8p SYMBOL cap 320 96 M90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value .3p SYMBOL res -208 96 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 100e6 SYMBOL cap -16 128 R0 SYMATTR InstName C4 SYMATTR Value 101p SYMBOL ind -64 224 R180 WINDOW 0 -15 89 Left 2 WINDOW 3 -42 28 Left 2 SYMATTR InstName L1 SYMATTR Value 240u SYMATTR SpiceLine Rser=.1 SYMBOL res 432 128 R0 SYMATTR InstName R1 SYMATTR Value 20meg SYMBOL res 176 96 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R3 SYMATTR Value 950k TEXT -336 280 Left 2 !.ac lin 1e6 995000 1050000 TEXT 176 96 Left 2 ;A TEXT 48 96 Left 2 ;B TEXT -200 8 Left 2 ;The voltage at point A is 1/2 the voltage at point B, \nSo looking into the .3pf cap the impedance is about 950k. TEXT -224 376 Left 2 ;If I remove the 950k and put a 4pf stray cap to ground it would just add\nto the 101pf cap in the resonating circuit. So I don't see how the\nstray capacitance will lower the input impedance when used to\n measure an LC circuit. TEXT 48 464 Left 2 ;Except for the capacitor's loss resistance. TEXT 256 128 Left 2 ;4pf\ns\nt\nr\na\ny