External clock for charge pump - heterodyning fix

[thelonious]

There's a known heterodyning issue with the Timeline delay (especially the Grit parameter) and certain pedals that use charge pumps. One of my DIY builds was heterodyning with the Timeline, and changing the charge pump to a different type didn't fix it. I made a little external clock circuit with a 40106 and used it to drive the charge pump's oscillator pin. When I got the clock up to ~52kHz, it fixed the problem no matter where the Grit knob is set.

My questions are: 1) Do I have to disconnect the Boost pin if I do this? It seemed to work either way, but I don't want to kill my charge pumps. 2) Are there any downsides to external clock at 50kHz, other than the $1 spent in parts and a bit of board real estate? I still have a lot to learn about charge pumps, so I'm hoping somebody can verify, "Nah, it's cool," or, "STOP IT YOU WILL DESTROY ALL THINGS"

[thelonious]

Here's the kind of thing that worries me:


Should I care that I made it less efficient by boosting the frequency? I'm guessing this would be a problem if I had a high current draw application. As it is, I'm just powering two 4558's and a JFET input buffer with it.



...now that's just obnoxious, because it might heterodyne on a hot day but not later at night if the temperature changes. Now wonder these things are hard to diagnose.