I built 3 voltage controlled oscillators the other week as the first part of a dronebox (https://www.schmitzbits.de/dronebox.html) using a cd40106be IC. They seemed to be functioning correctly.
I've now built out the rest of the circuit (though I am using a cd4051be as a demultiplexer instead of the 74HC151), but then noticed one of the oscillators always seemed "on" rather than oscillating. At first I suspected a loose/broken wire because it would work when I was holding it and stop when I let go.
I figured it would be quickest and easiest to just swap out the potentiometer - cut out the old one and solder in a new one so did that. Got the same result, and noticed a second oscillator exhibiting the same behaviour.
Experimenting a little more, it seems like the oscillators work fine if I physically hold the potentiometers by the input terminal. When I let go, they stop.
I looked over the data sheet again and realized I had not grounded the unused inputs on the IC as it recommends, so I did so to rule that out but the original issue remains.
Does anyone have any suggestions for me? I don't think a loose connection is the issue.
I've now built out the rest of the circuit (though I am using a cd4051be as a demultiplexer instead of the 74HC151), but then noticed one of the oscillators always seemed "on" rather than oscillating. At first I suspected a loose/broken wire because it would work when I was holding it and stop when I let go.
I figured it would be quickest and easiest to just swap out the potentiometer - cut out the old one and solder in a new one so did that. Got the same result, and noticed a second oscillator exhibiting the same behaviour.
Experimenting a little more, it seems like the oscillators work fine if I physically hold the potentiometers by the input terminal. When I let go, they stop.
I looked over the data sheet again and realized I had not grounded the unused inputs on the IC as it recommends, so I did so to rule that out but the original issue remains.
Does anyone have any suggestions for me? I don't think a loose connection is the issue.