Ken said:
.. Sorry , I am not sure what you mean by that. I know you are talking about
a voltage follower with unity gain , but what for.
I have added a second cirduit to the site:
http://www3.sympatico.ca/lerameur/
Ken
Your first circuit was nearly there!. Needs a discharge path across C3.
Probably more important is that the circuit has a perfectly stable state in
the non oscillating condition that you noted.
A sim needs the comparitor "+" input holding at 0V until the circuit has
stabilised. Releasing it will then give the 'kickstart' to force the circuit
into it's oscillating mode.
Difficult to make a 'good' circuit given the small number of components and
how they all notice each other. Really a couple of monostables and a
flip-flop wouldn't go amiss.
Below is similar but working circuit in the "LTspice" format. Includes a bit
of hysteresis for the comparitor, a transistor for the 'switch' and a CR to
give a rough LC energising pulse. Should though be buildable for real.
Side note; Tuned circuit Q factor can be measured simply as counting the
number of cycles to the point where the voltage has dropped to 4.3% of the
initial voltage. [ InitialV / (e^pi) ]
john
Version 4
SHEET 1 880 680
WIRE -576 -48 -576 -128
WIRE -576 64 -576 32
WIRE -576 96 -576 64
WIRE -576 208 -576 176
WIRE -496 64 -576 64
WIRE -496 112 -496 64
WIRE -496 208 -496 176
WIRE -400 160 -400 96
WIRE -400 176 -400 160
WIRE -400 272 -400 256
WIRE -368 64 -496 64
WIRE -368 96 -400 96
WIRE -336 -128 -576 -128
WIRE -336 48 -336 -128
WIRE -336 160 -400 160
WIRE -256 -128 -336 -128
WIRE -256 -48 -256 -128
WIRE -256 80 -304 80
WIRE -256 80 -256 32
WIRE -256 160 -272 160
WIRE -256 160 -256 80
WIRE -176 272 -400 272
WIRE -176 320 -176 272
WIRE -176 512 -176 400
WIRE -160 -128 -256 -128
WIRE -160 -112 -160 -128
WIRE -160 0 -160 -32
WIRE -112 272 -176 272
WIRE -112 336 -112 272
WIRE -112 512 -112 400
WIRE -96 80 -256 80
WIRE -80 272 -112 272
WIRE -16 -128 -160 -128
WIRE -16 -48 -16 -128
WIRE -16 80 -32 80
WIRE -16 80 -16 16
WIRE 32 -128 -16 -128
WIRE 32 -64 32 -128
WIRE 32 80 -16 80
WIRE 32 80 32 16
WIRE 48 272 -16 272
WIRE 48 352 48 272
WIRE 48 512 48 416
WIRE 64 80 32 80
WIRE 128 -128 32 -128
WIRE 128 32 128 -128
WIRE 128 272 48 272
WIRE 128 272 128 128
WIRE 128 288 128 272
WIRE 128 400 128 368
WIRE 128 512 128 480
FLAG -160 0 0
FLAG 128 512 0
FLAG 48 512 0
FLAG -112 512 0
FLAG -176 512 0
FLAG -576 208 0
FLAG -336 112 0
FLAG -496 208 0
SYMBOL voltage -160 -128 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 10
SYMBOL pnp 64 128 M180
SYMATTR InstName Q1
SYMATTR Value 2N2907
SYMBOL ind 112 384 R0
SYMATTR InstName L1
SYMATTR Value 461m
SYMBOL cap 32 352 R0
SYMATTR InstName C1
SYMATTR Value 15.27µ
SYMBOL res 16 -80 R0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL cap -32 64 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value 1µ
SYMBOL diode -16 256 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL cap -128 336 R0
SYMATTR InstName C3
SYMATTR Value 1µ
SYMBOL res 112 272 R0
SYMATTR InstName R3
SYMATTR Value 1
SYMBOL res -192 304 R0
WINDOW 3 28 84 Left 0
SYMATTR InstName R2
SYMATTR Value 1meg
SYMBOL Opamps\\1pole -336 80 R0
SYMATTR InstName U1
SYMATTR Value2 Avol=1Meg GBW=1Meg Slew=1Meg
SYMBOL res -592 -64 R0
SYMATTR InstName R4
SYMATTR Value 47k
SYMBOL res -592 80 R0
SYMATTR InstName R5
SYMATTR Value 22000
SYMBOL cap -272 144 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C5
SYMATTR Value 10n
SYMBOL res -384 272 R180
WINDOW 0 -20 48 Left 0
WINDOW 3 -35 28 Left 0
SYMATTR InstName R8
SYMATTR Value 1meg
SYMBOL diode 0 16 R180
WINDOW 0 24 72 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL cap -512 112 R0
WINDOW 0 23 8 Left 0
WINDOW 3 25 50 Left 0
SYMATTR InstName C4
SYMATTR Value 10µ
SYMBOL res -272 -64 R0
SYMATTR InstName R6
SYMATTR Value 2k2
TEXT -584 288 Left 0 !.tran 10
TEXT -480 48 Left 0 !,ic v(n002)=0
TEXT -560 48 Left 0 ;("Pot")
TEXT -440 -8 Left 0 ;(Comparitor LM393)
TEXT 64 480 Left 0 ;60Hz