# 3340 VCO Schematic for PCB design **URL:** \ **Category:** DIY STUFF\ **Created:** [April 25, 2020, 2:24am UTC](https://lookmumnocomputer.discourse.group/t/3340-vco-schematic-for-pcb-design/730 "2020-04-25T02:24:13Z")\ **Posts on this page:** 1\ **Showing post:** 18
**Author:** ![fredrik](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/fredrik/32/682_2.png) [@fredrik](https://lookmumnocomputer.discourse.group/u/fredrik)\ **Post date:** [May 3, 2020, 9:03am UTC](https://lookmumnocomputer.discourse.group/t/3340-vco-schematic-for-pcb-design/730/18 "2020-05-03T09:03:42Z")
Couple of potentiometer suggestions: - For the VR2 scale trimmer, the target resistance for the combination of 24k and pot is ~30k, so you may want to use a 10k there to put the target closer to the center of the pot. Also, the symbol is a bit strange, but I guess that’s a Kicad thing. - For the VR1 tuning pot, connecting it in series with the summing resistor results in a non-linear and somewhat limited tuning range. A more “correct” approach would be to connect it as a voltage divider, like it’s done in the performance VCO. See [here](https://lookmumnocomputer.discourse.group/t/cem3340-as3340-pot-question/602/15) for a discussion of some alternatives used in LMNC designs. Another tip is to make sure the timing capacitor C2 footprint is large enough that you can fit a quality film capacitor there, and not just tiny ceramic (see [here](https://lookmumnocomputer.discourse.group/t/3340-vco-schematic-for-pcb-design/730/2)). --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/3340-vco-schematic-for-pcb-design/730)._