audioguru said:
My extremely low distortion oscillator uses a CD4018 to make a stepped 10-times oversampled sine-wave.
How did you manage to get those odd ball resistor values? I was told if the resistor values are as designed, the first harmonic would be the 19th(at -26dB) for a ten stage wave generator.
I used a 12V supply to keep down the output resistance of the CD4018. The resistors are a matched pair (I selected them to be the same) of 47k and another matched pair of 75k, 5% 1/4W metal film.
I simply scaled-up the 1% resistor values recommended by Don Lancaster in his Cmos Cookbook. He says with a 10-steps wave, the 9th and 11th harmonics are down to 1/10th or about -20db. I matched the resistors for low 2nd, 4th and other low frequency even-harmonics. :lol: