Is John Popelish here? I changed the labeling since my last post. I am still having difficulty to fully grasp this circuit. My next questions are as follows:
I also removed the LED because we can see the simulation without it, and it does not (I think) effect the analysis.
I have noticed that if we increase R2 from 47K to 2M the circuit will still oscillate, but any further increase and the circuit will not oscillate. I was wondering if I could obtain a formula to calculate the maximum value (which is
2M by inspection of simulation results)following is the lt spice asc file as modified by me:
Version 4 SHEET 1 880 680 WIRE 48 64 176 64 WIRE 240 112 240 320 WIRE 160 320 240 320 WIRE 240 320 240 384 WIRE 32 320 96 320 WIRE -48 320 -96 320 WIRE -96 320 -96 112 WIRE -16 112 -96 112 WIRE -96 112 -96 0 WIRE -96 -80 -96 -144 WIRE -96 -144 240 -144 WIRE 528 -144 528 -128 WIRE 240 -144 240 16 WIRE 240 -144 528 -144 FLAG 48 160 0 FLAG 240 464 0 FLAG 528 -48 0 SYMBOL res 224 368 R0 SYMATTR InstName R3 SYMATTR Value 50 SYMBOL cap 160 304 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C SYMATTR Value .47µ SYMBOL pnp 176 112 M180 SYMATTR InstName Q2 SYMATTR Value 2N3906 SYMBOL res 48 304 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R2 SYMATTR Value 47k SYMBOL npn -16 64 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res -112 -96 R0 SYMATTR InstName R1 SYMATTR Value 4e6 SYMBOL voltage 528 -144 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value PULSE(0 9 0) TEXT -114 506 Left 0 !.tran 10s