I've set up this circuit on breadboard ( C1 being electrolytic and others disk) with Q1 as 2n3904. The simulation is perfectly fine and the oscillator works in the simulator as expected. However, the situation with the actual circuit is a bit different.
No matter what inductor L2 I choose, the frequency is always 210 KHz. I switched 47 uH with 4.7 and 10 uH; but its always 210 KHz. Even more disturbing is the fact that even if I remove some components from the circuit, ( I removed C1 and L2, not simultaneously though), and measure from L1, its still 210 KHz. To make matters worse, I just randomly waved the oscilloscope probe in air. and it still records 210 KHz ( I even put the probe on my head, and it seemed like my brain generates 210 KHz as well ! ).
So whats going wrong here ? And whats the deal with 210 KHz ?
Best Answer
I think your test equipment has a problem... what happens if you touch the probe with one finger and approach a power outlet (50-60HZ) with your other hand? If you still read 210KHz instead of 50-60Hz, you definitely have a test-equipment problem. Do you maybe have a "data hold" function engaged?