APC’s plus passive filters and easy fx plus a baby8 can sound brutal. (In an awesome way)
1 Like
You should change the labels from “Input#” to “Pin #”, because an input which is really an output could be confusing to those who don’t already know what you mean.
1 Like
it’s not mine, i just found it on the web to help about the number order of the pin, but yes it might be wise
1 Like
Hi guys,
So after building a new circuit of LMNC’S VCO with an as3340 chip, I have finally got sound. However, the pitch is high and the trimpot I’ve used is not allowing me to lower the pitch, but instead only allows me to adjust it to go even higher. Just wondering if anyone’s got any ideas why this is and what I can do to adjust the pitch to go lower.
Cheers
1 Like
That sounds like a third-stripe issue on the resistor. Make sure you don’t have a 10k in place of a 100k (etc.) somewhere. That’s my only idea.
Check reference voltage, and voltages coming off the individual pins of the rotary. Should be ref(4v)-3v-2v-1v-0v. If rotary is good then the prob is somewhere after that. Check the trim pot values and the resistors with ur multimeter like @Maxhirez says especially those after the rotary
3 Likes
Performance or DYI/stripboard? If the former, which trimpot are you tweaking – there’s the reference voltage trimmer (RV3) CTorp pointed you to (which is used by the octave selector and the fine tuning knob), but also coarse tuning/centre note (RV6), tracking (RV1), and high frequency adjustment (RV8) and they all do different things.
Recommended order afaik is to trim RV3 with a multimeter, then use the octave selector and tuning trimmer (RV6) and knob (RV7) to dial in a mid note (datasheet suggests ~200 Hz or G3), then use the RV1 trimmer to make sure an octave is an octave (using a keyboard or the selector), and finally go as high as you’d like (datasheet suggests 10 kHz) and use RV8 to deal with any flatness. Once that’s done, you can set RV7 to a mid position and use RV6 to tune to scale.
(If you cannot get down to reasonable notes after trimming RV3, checking the voltages, and turning the octave selector and the tuning knobs to their lowest positions, you may have a bad frequency cap (C6))
EDIT: If you’ve built the stripboard layout, you only have coarse tune (same as RV6) for the first step, and the 10k trimmer (same as RV1) for the second step. C6 there is the 1nF next to the 3340.
1 Like
Hey, which easy FX do you mean, I´m also new and build APC and Weird Sound Generator and I´m interested in easy Effects.
1 Like
hi, i built some oscillators and sequencers and in some i added an MS20 filter, others a delay, a LFO , a looper …
in my opinion you may find some infos that may interest you
you can translate the whole site at the top right
2 Likes
Hi,
So here are a few pictures of the stripboard circuit for the VCO, which I had issues with (read above in thread), hopefully are reasonably clear. Just hoping someone could suggest what could be the problem for why the pitch is high from the module. I am a beginner, so I don’t know if capacitors and resistors need to be placed a certain way round on the board or the trimpot is the wrong way round??? not sure but hoping for some suggestions!!
Cheers
2 Likes
they do not touch some of your resistances? because some seem very close,
and the small one underneath ?
For this particular layout trimmer, resistors, and capacitors don’t have a particular orientation. When you encounter layouts with electrolytic capacitors those will.
2 Likes
oh okay, thanks for letting me know 
I believe I’ve placed all components in the way the schematic said to, so some of the resistors are quite close together. It might be because the green resistors I used are substantially larger than those of the others
Double check the value of the capacitors (they look physically small), especially the one next to the 3340, that is the main timing component that determines pitch.
Try grounding the unconnected leg of the course tune potentiometer, it should enable you to bring down the frequency.
4 Likes
thanks grounding the pot did the trick!
5 Likes
Lol I have been there.
2 Likes
Sorry, can’t help myself:
Hey there boy, you’ve got some big resistors there !
On a more serious note, those resistors are big because they are of a type that can withstand quite a bit of heat generated by high currents running through them. For audio signal applications, I’m not talking about a power amplifier’s final stage here, you can use the 1/8 Watt variants that are cheaper and smaller. So next time, consider buying low power variants.
For debugging your problem find out which components are responsible for the frequency of the VCO and check their values and connections.
4 Likes
If I see that correctly, the 1nf capacitor is not connected to pin 11 and 12 (capacitor / ground). It is connected to 10 and 13 (triangle output / linear FM input).
1 Like
@THOGRE by “easy” fx I mean simple RC filters, attenuators, fuzz, distortion and guitar fx kits and mods. Even bbd and simple delay. Many simple fx can be adapted for cv or simply starved of sufficient power to produce the much sought after odd or random.
(Sorry to take so long to reply.)
2 Likes