TL074 Will almost definitley lead to a non-functioning unit as documented by many people, the 072s are fine in the rest of the circuit though, the 324 is an important chip as it's the LFO at the heart of the circuit and can lock up, this circuit is a bit picky when it comes to certain things and that's a big one.DrNomis wrote:Hmmmm...as I recall,the LM324 is like having two JRC4558Ds in one package,the op amps in an LM324 are built using bipolar transistors,the thing about this particular IC is that it was designed to be able to be powered from a single supply rail,as well as dual supply rails,there isn't anything very special about this IC though,I might try building this pedal using a TLO74 (same pinout as an LM324) and some TLO72's,and I might try substituting a CD4049 for the CD4009,just for fun,might see if I can come up with a stripboard layout too...
The CD4049 and 4009 swap is also confirmed as working fine, with the 4049 possibly spending a longer time in the lower part of the sweep but that was never confirmed in blind tests.