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 Forum index » DIY Hardware and Software » Lunettas - circuits inspired by Stanley Lunetta
new lunetta addict,questions before first build
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cyrax



Joined: Mar 18, 2012
Posts: 3
Location: Greece

PostPosted: Tue Mar 20, 2012 2:29 pm    Post subject: new lunetta addict,questions before first build Reply with quote  Mark this post and the followings unread

Hi all!

I am new to both the forum and lunettas . I've been reading this subforum for a while ,gathering knowledge from all of you ,and firstly I want to say you are doing a great work!

I went ahead and bought some components to start experimenting and now I have some things I want to clear out before I start soldering

I have decided to build the sea moss sequencer for a start, I tested it on a breadboard (with resistors , not pots ) and it works perfectly. I was actually surprised how loud and full these tiny chips sound! (or maybe I am just fascinated Razz )

On to my questions:

From what i understand the first oscillator on the 40106 is the clock and the second provides the sound that is sequenced. If so , could i use a switch and banana jack or something like that so that I disable them and use other lunetta modules instead?
Also, could I use this sequencer with my korg monotron ?

As for pots instead of resistors , what would happen if I used 10K pots (that I have) ?
I also thought of using switches to turn on and off steps but for some reason I have a feeling that would not work

Finally, could you please tell me the correct way of wiring leds with a pull down resistor on the pots ?

That's all fpr now (at last!! Laughing )

I also want to apologise for the megapost and for any stupidity that might exist in it Razz Razz

PS this is the schematic , I found it here and I guess everyone is familliar with it , I just posted it so that it's in handy

Posted Image, might have been reduced in size. Click Image to view fullscreen.

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JingleJoe



Joined: Nov 10, 2011
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PostPosted: Tue Mar 20, 2012 3:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

No pull down resistor would be required on the pots because the resistors are being switched in and out of the feedback path of the oscillator, it's like having this (see attachment #1) except with more resistors and switches and the switches are built into the 4051 chip. In effect this gives you a stepped variable resistance.

P.S. Good choice of circuit, I love multiplexers Very Happy (like the 4051) They are so versatile!


1.bmp
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synthesist



Joined: Feb 17, 2011
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PostPosted: Wed Mar 21, 2012 7:36 am    Post subject: Reply with quote  Mark this post and the followings unread

regarding the banana jacks: you could leave the clock oscillator open and just plug it into the module when needed. So you can use it for a different module too.
Also you could solder the other divisions Q1 to Q12 on banana jacks to be able to switch them into the adress pins (A-B-C) to variate the rythm.

Just be carefull and ask for advice before you play the lunetta squarwaves into the monotron filter. The squarewaves are very hot and have lots of DC-portion...

Have fun building Smile Smile Smile

xonrad
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cyrax



Joined: Mar 18, 2012
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PostPosted: Thu Mar 22, 2012 11:14 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the replys guys,you have been very helpful!

JingleJoe , I am sorry , I didn't express what I wanted to say right, I am still confused with some terms. By "pull down resistors" I meant the resistors for the leds. I read more about that and figured it out. Nevertheless your post helped me figure out more about what's going on inside the 4051 Very Happy

Sunthesist , That was a mean thing to propose, you just upped my expenses on banana plugs a lot Razz Razz
I decided to go with the modular approach

And on to the new questions

I ve been reading again and again this very informative post by Rykhaard on this topic

he says :

Quote:
When you are having inputs that DO have something hooked up to them, it is a standard practice in music electronics to give the inputs a 100,000 ohm impedance


Quote:
Finally - as to Outputs, it has been standard practice since about the mid 1970's, to put a 1,000 ohm 1/4 watt resistor on to the output pin from the chip.


does this mean that every banana jack should have a resistor between it's connection and the I/O of the chip?

Second and last question that occured to me from the same topic
Quote:
A solution here (that I wasn't taught until 1991), is add a SMALL capacitor as close as possible to the power INPUT pin, of EACH of those chips.


this "reservoir" should go from the power pin to ground, or between the battery and the power pin?

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JingleJoe



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PostPosted: Thu Mar 22, 2012 2:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

The capacitor resevoir should go from + to ground, if placed in series with the chip you would get a quick blip then nothing; capacitors only conduct as they charge, thus when fully charged they block current, this is why they only allow AC through.
The purpose of the cap, just incase you didnt know, is to stop interference from power supply fluctuations, for exmaple, those incurred when something else using the same power supply draws significant current.

Not too sure about those 100k resistors though, I thought that was just the standard input impedance of voltage controled analogue doohickeys.

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