Low-distortion Audio-range Oscillator

My passive 1K Twin-T notch filter based on Victor's schematic. (I got pcb yesterday, in evening assembled and measured)
Simulated depth 75dB, measured 58dB.
See attached document for more


Nice and clean work! But I would combine notch and buffer amp. That's safer.



Are these original WIMA capacitors? FKP for 30 cents seems strange to me. A good FKP costs 1 euro.
 
Attached RF meter schematic. Will work with just a sensitive meter, but chances are good you can burn out the meter! So put in protection or a variable shunt resistor.

BTY WIMA is better! Measured both, along with many others.
 

Attachments

  • RF Meter.jpg
    RF Meter.jpg
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At these levels we have to begin questioning if the results are consistent over time or if who was running the manufacturing line that day makes a difference in the results. Or if the quality differences of the film makes a difference, or if the end soldering machine adjustment makes a difference, or if.......

But you get the point, we have very little data about consistency over time with these products at this level. Which is one of the reasons I believe Samuel leans towards COG for some of these things, the process is less complex to manufacture and may lead to more consistent results.

But whose to know. Who has the equipment and lots of spare time :)

Cheers
Alan
 
Yes, the capacitors test is not so easy. Also the different results may appear at different frequencies, signal levels and from piece to piece. Every example must be individually tested when needs to use it in a sensitive place. Anyway the film/foil Wima FKP2 and FKP3 are very good caps with relatively stable performance.