Comment by dvh
5 hours ago
It's super easy to build LC oscillator.
I made a program that generate random topology and uses spice simulation to find if it oscillate. The goal was to find some novel LC oscillators. It worked, it found many different oscillators. I let it ran for a while and soon I found out that the simplest possible LC oscillator has 1 inductor, 2 capacitors, 1 resistor and 1 transistor. I found many different variations of it, I called this class of oscillators "LCCRT oscillator" and it also always had 2 internal nodes so that's not very large search space (40000 combinations) so I generated all possible combinations and I found out there are exactly 12 distinct LCCRT topologies.
Basically any time cap connects to a rail it can be placed to other rail as well, and any time one rail connects via resistor, the resistor can also be moved to other rail. This creates 12 possible combinations. I tested them in real life and they are stable, even used one in metal detector.
Of course it found many different topologies. Some times they were unique, other times they could be simplified into already found oscillator. It can also use multiple transistors not just one. You can find entire project on github, it is a ngspicejs script: https://github.com/dvhx/lc-oscillator-finder
As a CS guy who got the absolute bare minimum introduction to electronics: why isn't the article about LC oscillators?
I get the impression that there was some requirement to use transistors that I was missing. The article briefly mentions some kind of inductor as a rare component.
"Novel". Those are all Collpits LC oscillator variants, circa 1918. All LC oscillator topologies were thoroughly investigated more than a century ago, hundreds of books have been written about them. A little more humility please
Passive circuits have been novel for a long time now, or at least very very quaint. It is hard to put much stock in a coil when it is banal to walk around with 100 billion transistors in your pocket.
One of my favorite books is Tremaine's Passive Audio Network Design, seems appropriate right now. Passive circuit design is great fun and a lost art.
Nice! Perhaps you could sort them based on Q-factor.
this is always the risk of posting on hackernews: a random commentator absolutely iq mogs the op.