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Here's an example that works; LTspice circuit list here:

Since the voltage drop across Q2's base-to-emitter junction will always keep Q3's emitter more positive than its base and, since Q3 is an NPN, it'll never be able to turn on and your circuit will be …

If you think of a crystal as being a tiny bell, it's easy to see how, if you hit it with a tiny little hammer, it would ring with a pure tone just like a big bell would if you hit the big bell with a …

The problem is the 741, which doesn't have enough gain at 200kHz to overcome the loss of the bandpass filter. Here's a schematic of the identical circuit with a decent opamp, which works, and the LTs …

Replace R27 with the three leftover gates of the the 7400 wired in parallel EDIT: Bad idea if the oscillator won't even run. Try the following circuit instead. … The oscillator is from Fairchild's AN118. If, for some reason, you can't access that document, it's also available here I've built a bunch of them and they always work. …

The output is oscillating because it takes time for the changes in the output voltage to propagate through the filter.

Try this: 1) Set the scope to single-sweep at a trigger level of about half of your supply voltage. 2) Connect one end of the capacitor, one end of the inductor, the scope ground, and the power supp …

There are two problems with your circuit, the diodes and the base bias resistors R15 and R16, the diode drops keeping the transistor bases above cutoff, no matter what, and the 330 ohm resistors putti …

You shouldn't need any kind of outboard "kicker" (except perhaps noise) to get an analog oscillator started. … output, you should look into implementing a Wien bridge oscillator. …

This seems to work pretty well, but... \$ \style{color:red;}{ CAVEAT \ \ !}\$ The purpose of this simulation was to determine whether a circuit topology was viable, and the components were selected …

This self-starts and seems to work pretty well: (note the reasonably fast unity-gain-stable opamp)

There's a caveat, though... make sure that the output capacitance of the disabled oscillator, during shutdown, isn't enough to load the enabled oscillator to the point where it can't clock the following …

Following is your schematic (sans the transformer secondary) and its circuit list generated with LTspice, the circuit list included so you can simulate/troubleshoot the circuit yourself and find whate …

Well, it looks like someone got their tit in a wringer over my previous answer, so here are the "sanitary" links to the data if you still need it :-) From Crystek, there's: and from TI: