# 1222 Tuner VCO Module **URL:** \ **Category:** KOSMO MODULES\ **Created:** [January 17, 2020, 5:33pm UTC](https://lookmumnocomputer.discourse.group/t/1222-tuner-vco-module/16 "2020-01-17T17:33:40Z")\ **Posts on this page:** 1\ **Showing post:** 27
**Author:** ![JonGreen](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/jongreen/32/203_2.png) [@JonGreen](https://lookmumnocomputer.discourse.group/u/JonGreen)\ **Post date:** [February 4, 2020, 9:28am UTC](https://lookmumnocomputer.discourse.group/t/1222-tuner-vco-module/16/27 "2020-02-04T09:28:53Z")
Oh, as a note, I built my #1112 Oscillator’s with ferrite beads as listed on the diagram, and they seem have enough resistance to cause PWM pitch drift when you change the PWM knob directly or apply a CV to the PWM input. This is a pretty common problem with the CEM3340’s as they are super sensitive to changes in current (on pin 3 if I remember right), but when I built my eurorack VCO Maximus boards, which are also 3340 designs, I used the same ferrites without issue so figured I would be ok. Unfortunatly this appears to not be the case. I will be taking them out and replacing them with jumpers to bypass the points like Sam does in his build video this weekend to see if it makes a difference. I also used the 47k resistor listed in the BOM which Sam swaps out for a 20k because he had the parts on hand, which might also be having an effect. They work a treat in the other modules mind you, although as with all things your milage may vary. Has anyone used a AS3340-HYB in this circuit? Alfa claim that its a drop in replacement for an orginal CEM3340 only having fixed the problems with the PWM being sensitive and causing changes in frequency, but I haven’t tried it myself. If anyone has a good opinion of them I might order another set of PCB’s and give one a go to see what its like. --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/1222-tuner-vco-module/16)._