Reason the 4049 based distortions use high value caps?

[tackleberry]

All the 4049 based distortions I see (andertons tube sound fuzz, insanity box, DoubleD) have a 4.7uf to 10uf electrolytic after the hex inverters. Whereas most other pedals will use something like a .1uf or 1uf cap between stages. Is it something inherent with 4049s that you need a polarized cap or a large value 4.7/10uf? Or can regular 1uf films be put there with no problems?

[dschwartz]

i´d say that´s only a design chioce..AFAIK, inverters have high input Z, but also high output Z, maybe that´s why big caps are used..but i have used smaller caps (even 5n) between inverter stages without trouble

[valdiorn]

i´d say that´s only a design chioce..AFAIK, inverters have high input Z, but also high output Z, maybe that´s why big caps are used..but i have used smaller caps (even 5n) between inverter stages without trouble

Digital logic usually has high input impedance, but that's because they operate at either end of the spectrum, 5V or 0V, and since a gate has 2 FETS (CMOS = complementary MOS), one of them is always in cutoff, so very little current flows. However, using a 4049 as an amplifier, you are running it in the active region, and there is actually a LOT of current running through there. Many people have noted that the chips get flaming hot after a while, and that 4049's are not the best idea for battery-powered pedals...