/diy/ - Do It Yourself

>>1793009
get U101A's input off the ground a little bit. you can't depend on any individual copy of the comparator having an offset voltage that leans in the direction you want (can be ±9mV over temperature and voltage). so give it ~15-50mV on the - terminal
you need logic gates if you want those fixed ratios. try a diode-AND connection as in pic, which is easily adaptable to a rotary 3P4T switch. if you want an OFF position, disconnect the topmost pullup

>>1793135
for a 50% square wave it is f(x) = sum(sin(n*x)/n) over all odd positive n
for any non-50% square wave there will be even-order harmonics