I managed to develop an astable multivibrator transistor square wave generator of ~710Hz. This generator will be used as sound for AM radio transmission. The sound must be amplified by an external circuit. The simulation and realization of the generator works fine, but when I want to snatch voltage from this generator at a certain point, it is getting unstable. I tried putting a capacitor across the voltage source for impedance matching and I could still not figure out why I could not make it work. I don't suppose the failure was just that. Below a picture of the circuit. How can I extend a basic circuit in conjunction with another one without having to many disadvantages? [![circuit][1]][1] Edit: As demanded below an example: [![preamp][2]][2] Edit2: The amplifier right from the square generator has the following example components: (The values can vary, I just tried with few ones, but had no luck.) [![preamp][3]][3] Edit3: I succeeded to make the circuits working together. I added a 100kohm resistor to the output of oscillator, but it suffered this time from less gain. Why did I do this? I intended to get a good signal output from the oscillator without changing its appearance and further to amplify it. I think I need a multistage amplification method. Here the circuit: [![loadv2][4]][4] The .asc file of LTspice: ``` Version 4 SHEET 1 1560 680 WIRE 256 -144 -64 -144 WIRE 1024 -144 768 -144 WIRE 176 -80 64 -80 WIRE 256 -80 256 -144 WIRE 256 -80 176 -80 WIRE 336 -80 256 -80 WIRE 448 -80 336 -80 WIRE 768 -48 768 -144 WIRE 64 0 64 -80 WIRE 176 0 176 -80 WIRE 336 0 336 -80 WIRE 448 0 448 -80 WIRE 768 48 768 32 WIRE 768 48 656 48 WIRE 848 48 768 48 WIRE 944 48 912 48 WIRE 768 80 768 48 WIRE 64 96 64 80 WIRE 96 96 64 96 WIRE 288 96 160 96 WIRE 368 128 208 128 WIRE 448 128 448 80 WIRE 448 128 432 128 WIRE 496 128 448 128 WIRE 656 128 576 128 WIRE 704 128 656 128 WIRE -64 144 -64 -144 WIRE 1024 144 1024 -144 WIRE 64 176 64 96 WIRE 448 176 448 128 WIRE 176 224 176 80 WIRE 176 224 128 224 WIRE 208 224 208 128 WIRE 208 224 176 224 WIRE 288 224 288 96 WIRE 336 224 336 80 WIRE 336 224 288 224 WIRE 384 224 336 224 WIRE -64 304 -64 224 WIRE 1024 304 1024 224 WIRE 64 368 64 272 WIRE 256 368 64 368 WIRE 448 368 448 272 WIRE 448 368 256 368 WIRE 768 368 768 176 WIRE 256 416 256 368 FLAG -64 304 0 FLAG 256 416 0 FLAG 944 48 out FLAG 1024 304 0 FLAG 768 368 0 SYMBOL npn 128 176 M0 SYMATTR InstName Q1 SYMATTR Value BC547B SYMBOL npn 384 176 R0 SYMATTR InstName Q2 SYMATTR Value BC547B SYMBOL res 48 -16 R0 SYMATTR InstName R1 SYMATTR Value 1k SYMBOL res 160 -16 R0 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 320 -16 R0 SYMATTR InstName R3 SYMATTR Value 100k SYMBOL res 432 -16 R0 SYMATTR InstName R4 SYMATTR Value 1k SYMBOL voltage -64 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 124 Left 2 SYMATTR InstName V1 SYMATTR Value 1 SYMBOL cap 160 80 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value 10n SYMBOL cap 432 112 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value 10n SYMBOL res 640 32 R0 SYMATTR InstName R5 SYMATTR Value 22k SYMBOL res 752 -64 R0 SYMATTR InstName R6 SYMATTR Value 220 SYMBOL npn 704 80 R0 SYMATTR InstName Q3 SYMATTR Value BC547B SYMBOL voltage 1024 128 R0 WINDOW 123 0 0 Left 0 WINDOW 39 24 124 Left 2 SYMATTR InstName V2 SYMATTR Value 12 SYMBOL res 592 112 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R7 SYMATTR Value 100k SYMBOL cap 912 32 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 1µ TEXT -24 440 Left 2 !.tran 0 200m 100m 1u ``` [1]: https://i.sstatic.net/bmoz41pU.png [2]: https://i.sstatic.net/MBPXUxkp.png [3]: https://i.sstatic.net/4h3qbyZL.png [4]: https://i.sstatic.net/nuuei1VP.png