# 3340 Square Wave Popping? **URL:** \ **Category:** DIY STUFF\ **Created:** [December 17, 2021, 8:07pm UTC](https://lookmumnocomputer.discourse.group/t/3340-square-wave-popping/4393 "2021-12-17T20:07:09Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [December 17, 2021, 11:29pm UTC](https://lookmumnocomputer.discourse.group/t/3340-square-wave-popping/4393/2 "2021-12-17T23:29:20Z")
Maybe here some infos 🙂 > [@Advice for troubleshooting 3340 based VCO](https://lookmumnocomputer.discourse.group/t/advice-for-troubleshooting-3340-based-vco/2077): > > This is a wiki post; please correct and improve! This is written regarding the 1222 Performance Oscillator module, but similar things apply to the simple stripboard oscillator or other oscillators based on the 3340 chip. For the stripboard version also see If you are not getting good tones from the oscillator, do the following. If with the 1222 you are also not getting good behavior from the tuner, don’t waste time on trying to fix that yet. Get good tones on the outputs first — the tuner won… > [@Glitches or ringing on the pulse output of the AS3340 and CEM3340](https://lookmumnocomputer.discourse.group/t/glitches-or-ringing-on-the-pulse-output-of-the-as3340-and-cem3340/752): > > While trying to calibrate/tune my #1222 VCO I used my oscilloscope to measure the frequency as I don’t have a good enough ear for tuning, and I got some weird readings from the scope. The frequency reading would sometimes jump up when it should be going down. After some poking around, I noticed that there was some high frequency oscillation on the falling edge of the pulse output. The lower the VCO frequency, the more ringing/oscillation on the falling edge, and it can get quite b… --- _[View the full topic](https://lookmumnocomputer.discourse.group/t/3340-square-wave-popping/4393)._