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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Beginner dummy questions.
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talkboxert



Joined: Oct 08, 2008
Posts: 14
Location: Amsterdam, Netherlands

PostPosted: Wed Oct 08, 2008 12:10 pm    Post subject: Beginner dummy questions. Reply with quote  Mark this post and the followings unread

Hey there. I'm completely new to mudule design and just starting my first project, Ken Stones simple wave folder:

http://www.cgs.synth.net/modules/cgs52_folder.html

As I'm laying this on a breadboard, a few questions arose, sorry if this seems completely stupid:

1 When connecting the in and outputs to a regular jack socket, is the wire connected to the ring or the tip? If connected to the tip, what happens to the ring? It stays unconnected??

2 Is the ground the same as Negative Voltage? I've replaced the 15K resistors with 12K ones in order to run this on 12 volts (eg. 8 penlite batteries....

3 What are the triangular symbols that point up and down from the 15K resistors and the pins 8 & 4 in the schematic? Are those connected to +v (pointing up) and -v (pointing down)?

4 Besides the Tri an Sine "IN" there is also another "IN" right after the Pot. What is this for?

Learning........




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PostPosted: Wed Oct 08, 2008 1:57 pm    Post subject: Re: Beginner dummy questions. Reply with quote  Mark this post and the followings unread

talkboxert wrote:

1 When connecting the in and outputs to a regular jack socket, is the wire connected to the ring or the tip? If connected to the tip, what happens to the ring? It stays unconnected??

2 Is the ground the same as Negative Voltage? I've replaced the 15K resistors with 12K ones in order to run this on 12 volts (eg. 8 penlite batteries....

3 What are the triangular symbols that point up and down from the 15K resistors and the pins 8 & 4 in the schematic? Are those connected to +v (pointing up) and -v (pointing down)?

4 Besides the Tri an Sine "IN" there is also another "IN" right after the Pot. What is this for?


1. tip, i belieive, is the right channel and ring is the left channel, sleeve is gnd. When mono connectors or jacks are used, ring is shorted to gnd.

2. No, gnd is not the same as negative voltage. gnd is the middle of the two, and should be thought of as zero volts.

3. The triangle up is positive supply voltage and the triangle down is negative supply voltage. It's a bit of an unclear way to draw it because triangle down is also used for ground, but there is a lot of variation in how people draw these things. Electronics is cross-cultural and goes back in history as you know, so there's been lots of ways to draw things.

4. That is the wiper of the pot, it indicates an internal contact that slides along the resistive surface of the pot to vary the tap location. You hook it up just like any other connection.

Hope that helps, anyone correct me if I mixed up anything especilly 1. which I'm new at and not too keen about. But then, I'm never all that certain about anything, haha. Cheers and have fun with your circuits.

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neandrewthal



Joined: May 11, 2007
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PostPosted: Wed Oct 08, 2008 8:43 pm    Post subject: Re: Beginner dummy questions. Reply with quote  Mark this post and the followings unread

talkboxert wrote:


4 Besides the Tri an Sine "IN" there is also another "IN" right after the Pot. What is this for?


The first IN represents the tip connection of your input jack going to the pot. The second IN represents the pad of the same name on the PCB where you connect the middle lug of the input pot. Basically, this just tells you where the panel mounted components end and the PCB ones begin.

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talkboxert



Joined: Oct 08, 2008
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Location: Amsterdam, Netherlands

PostPosted: Wed Oct 08, 2008 11:42 pm    Post subject: ground zero..... Reply with quote  Mark this post and the followings unread

Thanks a lot!!!

Quote:


1. tip, i belieive, is the right channel and ring is the left channel, sleeve is gnd. When mono connectors or jacks are used, ring is shorted to gnd.


Actually insted of ring/tip I meant ring/sleeve (mono connector)
So:

when using Mono connectors I should connect tip to the circuit and wire the sleeve to ground?

Quote:

2. No, gnd is not the same as negative voltage. gnd is the middle of the two, and should be thought of as zero volts.


Ok that's clear, but:

On a breadboard (or in any circuit) Where do do I derrive ground from?
Should I just connect one row to a ground source (eg. a metal watertap or Tube of my heating system) and use that as ground?

And how does this work on a PCB? Where does the ground come from?
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PostPosted: Thu Oct 09, 2008 12:28 am    Post subject: Reply with quote  Mark this post and the followings unread

I may not have the correct terminology, but I believe that a mono connector has tip and sleeve only. The tip is connected to the um, tip of the plug and the sleve is the long cylindrical contact. Ohm it out with a meter. You connect tip to the signal and sleeve to the ground.

Now, ground is hard to understand. Your home, be it house or apartment, has a metal rod driven into the earth to establish ground. This is connected to all of your wall sockets for safety. Thus, the voltage potential of the earth is ground, and that's why we cal it, um, "ground".

If you use batteries or isolated wall-warts to power your circuit, then you will have what is called a "floating ground", which means that everything in your circuit is referenced to the ground node but nobody knows what actual voltage potential that floating ground is at. So what do you do? You ground it, i.e. you connect it to ground.

Most likely this will be done by whatever you plug that cable into, as it will probably have a path to earth ground. Or else your scope probe will ground it. It's important to have good grounding because it prevents noise in your circuit, particularly 60 Hz noise from the power lines (or 50 Hz in many places).

I hope that was clear, good luck with your prototyping.

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andrewF



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PostPosted: Thu Oct 09, 2008 12:47 am    Post subject: Re: ground zero..... Reply with quote  Mark this post and the followings unread

talkboxert wrote:

On a breadboard (or in any circuit) Where do do I derrive ground from?
Should I just connect one row to a ground source (eg. a metal watertap or Tube of my heating system) and use that as ground?

And how does this work on a PCB? Where does the ground come from?


Just think of ground as 0V, it doesn't necessarily mean an earth connection.
By way of example
have a look at the CGS simple wavefolder
upwards pointing triangles indicate +15V (or +12V)
downwards pointing triangles indicate -15V (or -12V)
The downwards pointing triangles made of multiple lines are 0V
You can see in the schematic that pins 3&5 of the TL072 op-amp and a 1k Ohm resistor are all connected to 0V.

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

Now take a look at the PCB for this circuit, the two 0V holes on the left, in between the +15V and -15V holes, are where the power supply is connected. You don't have to use both 0V holes, there are two for reasons we don't need to consider now. If you follow the yellow path, which is the copper track from the two 0V holes, you can see another 0V hole, this one is for connecting a wire to the panel, for the 0V (also called 'ground') terminal on your jacks. Keep following the yellow track, you will see it connects to pins 3&5 of the op-amp and one end of the 1k Ohm resistor.
That's it, that is the 0V or ground connection
Posted Image, might have been reduced in size. Click Image to view fullscreen.

As for the power supply, check out the CGS one at http://www.cgs.synth.net/modules/cgs14_psu.html
You will see on the right side of the schematic the +15V, 0V and -15V holes, which are the outputs of the power supply PCB. You would connect these to the power input holes of your circuit.
At this stage of your diy career, I suggest you don't build a power supply, but buy one. You need a bipolar supply that puts out +15V AND -15V, current rating of 1Amp will be adequate (or +/-12V is okay too).

good luck, don't worry if things don't work the 1st time..or even the 2nd time... Smile
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talkboxert



Joined: Oct 08, 2008
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Location: Amsterdam, Netherlands

PostPosted: Thu Oct 09, 2008 1:34 am    Post subject: Thanks!!!! Reply with quote  Mark this post and the followings unread

Thank you all for the clear explanation and the very fast reply!!!

I want to continue breadboarding this afternoon so it's really conveniant that I got such quick answers.

Another 20 minutes and I will be able to start testing my Wave folder Smile


Just signed up yesterday and already a big fan of this forum!!!
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PostPosted: Thu Oct 09, 2008 2:17 am    Post subject: Re: ground zero..... Reply with quote  Mark this post and the followings unread

andrewF wrote:

Just think of ground as 0V, it doesn't necessarily mean an earth connection.


That's true, it's easiest to just think of ground as zero Volts. The bit about earth connections comes into play sometimes, but it is rare. You needn't worry about connecting your ground to true earth ground unless you have a ground problem or work with sensitive stuff like guitars.

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talkboxert



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PostPosted: Thu Oct 09, 2008 3:39 am    Post subject: ground Reply with quote  Mark this post and the followings unread

So basically I could just use an empty row on my breadboard to act as ground?

Would that mean that anywhere where it says ground doesn't really need to be conected to anything??

Or do all wires going to ground have to be attached?
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PostPosted: Thu Oct 09, 2008 4:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, you need to attach all the ground wires to that node. You can't just disconnect all the ground wires and expect your circuit to work. You have to have all the grounds tied together somehow. Yes, you could use an empty row on your breadboard to act as ground. Remember that the supply ground must be connected to that node also.

What we were talking about is whether you have to connect that 0V ground node to earth ground, and generally speaking you don't. There are situations when you need to use earth ground, but prototyping an audio frequency opamp circuit is not generally one of them.

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talkboxert



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PostPosted: Thu Oct 09, 2008 5:04 am    Post subject: ground zero..... Reply with quote  Mark this post and the followings unread

Quote:
Remember that the supply ground must be connected to that node also.


Could I use a true earth ground as ground as well? I want to use a regular 12v AC/DC adapter that seems to have no ground connection....

Just like when I would use 8 penlite batteries.... There would also be no designated ground...

Would the function of ground be just to let excess voltage (either + or -) flow away freely?
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PostPosted: Thu Oct 09, 2008 5:49 am    Post subject: Re: ground zero..... Reply with quote  Mark this post and the followings unread

talkboxert wrote:
Quote:
Remember that the supply ground must be connected to that node also.


Could I use a true earth ground as ground as well? I want to use a regular 12v AC/DC adapter that seems to have no ground connection....

Just like when I would use 8 penlite batteries.... There would also be no designated ground...

Would the function of ground be just to let excess voltage (either + or -) flow away freely?


OK, a few things here. for one, you cannot apply AC voltage or you will destroy the opamp. Also you need +/- 12V, not just +12V or -12V so you cannot use that DC supply either. Next, andrewF said to build or buy a +/- 15V supply, you should do that. And finally, electric current runs in loops, it does not "flow away freely" as you are thinking.

I'd Google up a "beginner's electronics" online web page and read that. You're going around in circles here asking us questions based on lack of fundamental knowledge. I'm not being critical, just suggesting, you know? I'd recommend some good reading on basic electronics.

Cheers and good luck!

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talkboxert



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PostPosted: Fri Oct 10, 2008 2:52 pm    Post subject: Working!!! Reply with quote  Mark this post and the followings unread

Thanks inventor.... I was moving a little to fast.

I got my basic info about components/electronics from a book about building guitar pedals and they only deal with 9V batteries to keep things very simple. Wich I liked.... But for the same reason they didn't talk about AC vs DC etc

So I did some research/readin as you sugested....

I just got my Doepfer DIY kit and this contains a 12v + and - PSU (with ground)

I hooked it up and the circuit is now humming away on the breadboard. Smile

I fed it with a sine wave from my soundcard, seems though as if the pot is particularly working on the last part of its rotation.

Dont know if this has to do with the fact that the system runs on 12v now in stead of 15 v (i did replace the 15k with 12k resistors...), or that thats just normal behaviour of the circuit.

but maybe this means I also have to choose a different value pot (now using 100K) <-- does this make sense?

Any other thoughts on modifications because of the 12 volts?

For my first circuit I knew It would have been handy to just stick to the exact specs but since I would like it to work in my doepfer system.,...

Thank you all again for the obvious but usefull tips so far. Can't wait to get the PCB....


Just wondering....Would it be correct to assume that you could also get a + and - voltage source by using 2 batteries with reversed polarity?

I have some old arp MSL modules that run on 2 9v batteries...
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PostPosted: Fri Oct 10, 2008 3:17 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey talkboxert, good to hear from you again. I don't know about the 15k resisitors. I forget my transistor theory, but it looks like a totem-pole gain stage with emitter degeneration, but I could be wrong about that. Changing the resistors from 15k to 12k may have been a poor idea, try putting 15k resistors in.

Also, you could get yourself a spice simulator and simulate the circuit. Just a thought.

You didn't say which extreme end of the pot works, min or max setting.

Yes on the battery question. If you put the = end of one battery on ground and the + end of the other on ground, you get a +/- 9V supply.

My advise is the same: skim the web for electronics tutorials, and maybe think of getting another good book. There are some excellent books that folks here have recommended, try searching old posts.

Take care and have fun.

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Blue Hell
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PostPosted: Fri Oct 10, 2008 3:43 pm    Post subject: Re: Working!!! Reply with quote  Mark this post and the followings unread

talkboxert wrote:
seems though as if the pot is particularly working on the last part of its rotation.


Are you sure it is a LIN pot and not a LOG? A LIN put could have an A somewhere in the value and a LOG pot a B, as in 100KA.

Quote:
Just wondering....Would it be correct to assume that you could also get a + and - voltage source by using 2 batteries with reversed polarity?


What do you mean by "reversed polarity"?

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PostPosted: Fri Oct 10, 2008 5:08 pm    Post subject: Re: Working!!! Reply with quote  Mark this post and the followings unread

talkboxert wrote:


Just wondering....Would it be correct to assume that you could also get a + and - voltage source by using 2 batteries with reversed polarity?

I have some old arp MSL modules that run on 2 9v batteries...


I haven't tried these but -
Posted Image, might have been reduced in size. Click Image to view fullscreen.

there is a description on this page after a big old scroll
http://www.headwize.com/projects/opamp_prj.htm
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talkboxert



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PostPosted: Sun Oct 12, 2008 8:19 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
You didn't say which extreme end of the pot works


The maximum end.

Quote:
try putting 15k resistors in.


Could this be done even now I run the circuit on +/-12 volts?
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