Sine wave Generator Circuit built with a Transistor

In this video, we demonstrate a sine wave generator circuit built with a transistor.

[dangreenspan]

To all those who have tried this and found it doesn't work: It will work eventually. At first it didn't work for me either, because the transistor I used wasn't correctly biased using the circuit shown. I replaced the divider at the transistor's base with a 20K pot and adjusted it to find the sweet spot. Also I found that a slightly higher voltage, 12V, worked better for me. I must have tried 50 individual transistors, and almost all of them oscillated in this circuit. Any transistor with a beta below 100 may not work, but most "reasonable" small-signal transistors will work in this circuit, producing an output of about 1.2KHz at around 7V P-P. Once you get it working, you can start substituting R/C values to get different frequencies.

[johnm]

The circuit as shown in the linked article won't work for two reasons. First, the DC bias is wrong. Replace the 1K resistor between the base and collector with a 10k resistor. Replace the 2k collector load resistor with 1k. Replace the 1k8 resistor between the base and ground with the more readily available value of 2k2. That will bias the transistor so that its collector is at about 4 volts, approximately half of the supply voltage. Second, the AC feedback is wrong. The 470n capacitor couples the output from the collector back to the CR filter/phase shift network but it is also part of that circuit so replace it with 100n, the same value of the other capacitors in that network. Then it will oscillate. I get over 5 volts peak to peak voltage swing on the output. To change the frequency experiment with the values of the four capacitors in the network but make them all the same value. You can change the three 1k resistors in the network too but not by very much. You can reduce them to about 470ohm but not much lower than that. You can increase them to 2k2 but not much higher than that. Again keep all three the same value. Make sure you correctly identify the terminals of the transistor you're using and use a 9 volt supply for the bias values given.

[morogojojo]

Very good and practical! thank you very much.

[CoolDudeClem]

Why wont this circuit work, I built it up EXACTLY as in the schematic and I get NOTHING, the only thing different is how I layed it out on the breadboard. I've tried EVERYTHING I can think of but there's absoluteness no sign of any oscillation whatsoever, I've been pouring over the circuit for about 5 hours continuously trying to work it out, everything is connected where it should be, all the components are the exact same, I tried several different transistors including 2n3904, nothing is shorted or open but but still no output on my scope., the trace is just a flat line.

[johnrobinson]

This one doesn't seem to actually work as given. The schematic and board layouts are different.

[amirmahmoud]

that's very good man. I just have one question, how much is the frequency range ? (minimum & maximum) And thanks a lot

[GUPRPEET-Singh]

sir can you plz make a video on how to get sine wave from ic 555 timer...

[nskmda]

misleading $hit. just modeled it and of course it doesn't work per schematic. do u mind providing correct schematic then?

[techaneyfortech]

it doesn't work make ensure that your circuit is working well