Absolutely superb - I'll get this up on the breadboard. The extra modulation control will be great - I had tried implementing that with just a 500K pot as a "level" control off the sawtooth, but it didn't work terribly well. I'm guessing the extra emitter-follower will make it much more stable.OK, here's my idea. The audio modulation will be dependent on the beta of Q2, so your results may vary.
Also, I didn't know what your audio input amplitude was. I chose 200mV p-p.
200mV is about right for the input.
One (last, I promise) thing - what's the benefit of placing the LED load on the emitter here?
That's LTSpice you used for the simulation? I really need to get up to speed on that.
Thanks again - much appreciated.