How do I improve my circuit schematic so that I obtain the desired result in LTSpice?

I have recreated a circuit of a Sine oscillator from a textbook. However, when I simulate it, the result is different to what is expected.

I have compared the 2 schematics and they are similar in every sense. The only difference is that the Textbook specifies a Philips NPN transistor and my library only contains a NXP equivalent.

Any insight that anyone can provide will be very much appreciated.

Textbook schematic

Textbook result

My LTSpice schematic

My LTSpice result

  • 2
    \$\begingroup\$ Philips sold off their semiconductor division ... as NXP. \$\endgroup\$
    – user16324
    Commented Oct 27, 2020 at 15:39
  • \$\begingroup\$ Thanks for the heads up!! I was thinking something similar, but couldn't understand why some of the transistors still bear the Philips name. \$\endgroup\$
    – aLoHa
    Commented Oct 27, 2020 at 15:42

1 Answer 1


I've noted the differences in your circuits in the images below:

enter image description here

  • The resistor notated as R5 is different by 10 fold
  • There is a connection between capacitors C1 and C4 that shouldn't be there
  • \$\begingroup\$ Spot on, unlike OP's "similar in every sense". \$\endgroup\$ Commented Oct 27, 2020 at 14:48
  • 1
    \$\begingroup\$ Thanks very much for the spot, especially with regards to the connection between C1 and C4. The resistor value itself is not the cause of the issue, as I've accidentally uploaded a latter version of the circuit with a greater resistance that helps to smooth out the output. \$\endgroup\$
    – aLoHa
    Commented Oct 27, 2020 at 14:56
  • \$\begingroup\$ By the way, do I receive a score for my question? :) \$\endgroup\$
    – aLoHa
    Commented Oct 27, 2020 at 15:00
  • 1
    \$\begingroup\$ I had already upvoted it ;-) \$\endgroup\$ Commented Oct 27, 2020 at 15:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.