Questions...

[madskill42]

Hello,

I've got some questions regarding Lunetta modular synthesis.

1. Thing that bothers me most: Grounding unused pins. As I understood, connecting for example 4017 sequencer output pin to VCO CV pin makes VCO bleep. But what will happen if VCO is not connected? And VCF and all those other unused pins? It will produce some unwanted glitches, interference, or something goofy, right? I don't quite understand how to get around this problem, or whaever is it a problem at all.

2. Power supply and power consumption. This bothers me too. I've got a certain amount of modules I'd like to build, and I don't know how to power them. Or with what. Transformer with voltage divider comes to mind, but I hope there will be some much more elegant solution. I'm afraid single 9v battery cannot handle all those modules with CMOS chips and blinking LEDs. Also, trick with small cap before power pin at every CMOS chips seems to be a good hint, too.

3. Reseting 4017 sequencer. As I have just 2 4017 chips right now, and I still was not able to convince myself to build some prototype sequencer, I'm still wondering how to keep it all synced. I mean, If I have two sequencers running from same clock, first sequencer running 8 steps and second one running like let's say 5 steps (polyrhytms are one of my main thing to look forward to ) and I'll switch second seq to 6 steps, will be still in sync with first one? Won't it just run at different phase? Again, as I understood, number of steps is decided by connecting pin Xth pin (where X is number of desired steps + 1) to reset pin, right?

4. And finally, I've ordered 50 mono jacks with piece of wire for quite good price (like 5$! yey! ). But then I've realized, that to connect stuff in modular world, you need just one "wire" not "two wires" (ie. mono jack). I'm not decided if I'm going to use them now. Anybody got an idea how to use them?

Thanks a lot for a answers and thanks for a wonderful week I spend, as I was reading all these great informations on the forum!

[Kabzoer]

Hello! I don't really know much about grounding unused pins, but to be sure, just wire them to ground with a 100k resistor.
For the supply you can use a LM7805 or LM7809.
As far as i know, a 4017 always runs in sync with the clock, so don't worry about that.
Those mono jacks are good, you can just wire up one of the wires or put ground on the other.

Hope this helps you!

[inlifeindeath]

only need to ground inputs. output can be left open.

[tjookum]

there has been so much confusion on pulldown resistors, and I can see where it's coming from. Inputs, outputs, 100k's. Not really hard for someone used to electronics but it can be hard when you start out.

There are basically just a few simple rules for working with cmos:
-They are sensitive to static electricity, so try not to work on carpet or wear a grounding wristband. (In my experience they are pretty tough and normal handeling isn't much of a problem)

-Add a 0.1uF close to the power connections of each ic to avoid noise.

-ground all inputs you will never use.

-Use a 100k to ground when you are planning to use the input as a patchpoint(not ciritcal, 10k will work but 100k is the standard)

hope this clears it up.

[Psyingo]