NC - No connection

Started by timd, December 25, 2012, 11:32:35 PM

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timd

From what I understand, a NC or N.C. means "no connection". For breadboarding a schematic with an NC for an IC leg or transistor pin, do I just not connect anything to it or bend the NC pin up so it doesn't make connection with the breadboard at all? I remember seeing a build or two awhile ago in the pictures thread where an IC pin was bent straight out and wasn't soldered down, and I'm wondering how to approach this. The project I'm looking at has a NC for an IC pin and NC for a transistor pin.

armdnrdy

As long as there is nothing else connected to the row where the N.C. "leg" is, it can be inserted in the breadboard.

What circuit is it and which IC are you refering to? Some IC pins have to be connected to either V+ or ground.
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed! ;)

garcho

NC for a transistor lead?
Sounds like a Devi Ever thang

If you're breadboarding something CMOS, tie the unused inputs to ground.
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"...and weird on top!"

timd

It was a white noise generator I was planning to add to a circuit I have been working on:

http://www.flickr.com/photos/secondhandsynth/4501573713/

I breadboarded it and really wasn't what I was looking for (I'll have to check my connections) What I got was a little white noise, but mostly just oscillations.

armdnrdy

Here's a few that you might try.

Here's R.G.s Low Fidelity pedal. You can use the "noise" section.
http://www.geofex.com/FX_images/lofi.gif

Here's a simple design that promises 30db more noise than traditional designs and claims to be very resistant to oscillation.
http://www.extremecircuits.net/2010/04/simple-white-noise-generator.html
I just designed a new fuzz circuit! It almost sounds a little different than the last fifty fuzz circuits I designed! ;)

timd

Cool stuff. In the extreme circuits link, its set up for 12V. Do you think it would do well at 9V? Also, there is another link at the bottom section there for a rain sound generator running off 9V. I assume "rain" would be a harder sounding version of a white noise? I check it out and report back if I have success.

PRR

> It was a white noise generator

For reasons which may be mostly historical, the standard analog noise generator is the B-E junction of a Si transistor, reverse-biased, no connection to C. Given ample excess voltage (9V is marginal) it makes lovely broadband hiss for just a few cents.
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garcho

What would you consider proper voltage?
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"...and weird on top!"

PRR

Much-more than the 7V breakdown.

9V, especially saggy, is hardly any "more" at all.
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timd

*Update to the first schematic I posted with unwanted oscillation issues - the 10 uf cap from pin 1 to 8 was seemingly way too big. I lowered it to 100 nf and it was fine. You can even get away with no connection from 1 to 8 if need be. I can toy around with different values to optimize the circuit to my tastes. Also, the NPN transistor choice seems to make a slight difference in sound.  I never did use the speaker like in the schematic, so I ran pin 2 of the 386 chip to ground instead of the speaker.