I'm trying to solve this problem for some hours now but without success, I thought I would ask for help here. I detailed my doubts in the image below :

Both Coupled inductors have couple coeficient k = 1 and are ideal (infinite quality factor) and these are the information:

C_b = infinite, beta = 200, V_BE = 0.7V, V_C_sat = 0


simulate this circuit – Schematic created using CircuitLab

The first thing I need to know how C1 is related to resonance frequency f of the circuit. It seems like I can choose a frequency and I automatically get a needed value for C1.

The second thing I need to know is what value for L2 should choose so that I get the maximum feedback rate at the resonance frequency f

I have a lot of doubts I don't know if the circuit constitutes a Colpitts or Hartley oscillator and if I can use the known formulas and then how I would apply it my circuit.

  • \$\begingroup\$ Where did the circuit come from and what else was contained in the article about it? \$\endgroup\$
    – Andy aka
    Commented May 15, 2013 at 9:11
  • \$\begingroup\$ Depending on who you ask, this circuit is called an Armstrong Oscillator or Meissner Oscillator: en.wikipedia.org/wiki/Armstrong_oscillator With this info, you can at least search a bit more. \$\endgroup\$
    – zebonaut
    Commented Aug 13, 2013 at 5:45
  • \$\begingroup\$ Instead of building it yourself, there are modules that are stable and can do this for you over a very wide range of frequencies: electronics.stackexchange.com/questions/305303/… \$\endgroup\$
    – SDsolar
    Commented May 14, 2017 at 15:22

1 Answer 1


the L and C form an LC tank. Frequency is given by:

enter image description here

  • \$\begingroup\$ Thanks, do you have any clue about how to calculate L2 so that we get the maximum feedback rate at the ressonance frequency fo ? \$\endgroup\$
    – nerdy
    Commented May 15, 2013 at 1:49
  • \$\begingroup\$ From your schematic it looks like L1 and L2 are from a dual winding inductor so they should be the same value. \$\endgroup\$
    – EEToronto
    Commented May 15, 2013 at 1:53

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