Hi guys,
first off, I am new to this forum and also new to electronics. I have been developing software for many years and am now trying to make a little design.
The design are two PWM generators which each have a jack input and a jack output. For the jack input I add a pull up resistor so that when nothing is connected, the input is still high and thus the generator is driven. So far, so good and it works well. The outputs work well, too, I measure 0v and about 3.8v (low and high).
The question boils down to a problem I'm having when I connect the output of one generator to the "gate/enable" input of a second. In that case, the output (an op amp as comparator) varies between the previous 3.8v and now 0.6v... which I believe is sinking current from the pull up resistor of the input jack... and that's enough to enable the other generator although that is contrary to my intentions.
I tried adding a diode after the op amp but that didn't work, it was as if nothing was connected through the jack at all and the pull up resistor set the generator enabled.
I am aware that I am probably missing some very basic concepts, but except for that my little project worked out well so far. I googled for hours but found no examples or anyone having similar issues. Hope someone can help
first off, I am new to this forum and also new to electronics. I have been developing software for many years and am now trying to make a little design.
The design are two PWM generators which each have a jack input and a jack output. For the jack input I add a pull up resistor so that when nothing is connected, the input is still high and thus the generator is driven. So far, so good and it works well. The outputs work well, too, I measure 0v and about 3.8v (low and high).
The question boils down to a problem I'm having when I connect the output of one generator to the "gate/enable" input of a second. In that case, the output (an op amp as comparator) varies between the previous 3.8v and now 0.6v... which I believe is sinking current from the pull up resistor of the input jack... and that's enough to enable the other generator although that is contrary to my intentions.
I tried adding a diode after the op amp but that didn't work, it was as if nothing was connected through the jack at all and the pull up resistor set the generator enabled.
I am aware that I am probably missing some very basic concepts, but except for that my little project worked out well so far. I googled for hours but found no examples or anyone having similar issues. Hope someone can help