# Need assistance with a basic circuit that outputs alphanumeric characters!

#### DarthNitpick

Joined Jan 24, 2018
8
So, the circuit I'm going to build is pretty simple as far as I can tell -- it's essentially just part of a proof of concept I'm trying to wrap my head around -- but I'm so new to this I can't really parse the dense literature around circuits!

I need a circuit to output an alphanumeric string of 30 fixed characters. This string would be used as an input for a completely separate component. Can someone help me understand what a circuit like that would that look like? I'm assuming it would have a lot of a very simple binary -> alphanumeric process going on, and some way to put each character into a string, so I'm trying to figure out the scope of its detail.

Thanks so much in advance!

#### philba

Joined Aug 17, 2017
960
My mind reading superpower is on the fritz...

Output how? On a display? Serial cable? Radio Transmitter? Also, what is the "completely separate" component?

#### BR-549

Joined Sep 22, 2013
4,938
DarthNitpick.........You will have to explain a lot better than that. Every detail makes a difference.

Don't use words that you have heard.....use words that you know.

Tell us exactly what you want to do. A general question, without details....has a thousand answers.

#### DarthNitpick

Joined Jan 24, 2018
8
I'll do the best I can!

So, first of all, think of it as art. What I'm trying to do is figure out a way to represent a 30 string character in the form of a circuit and then I will build other components that take that number and do various things with it. The point of this circuit is simply to exist as the physical, self-contained, circuit-based manifestation of that number.

To be even more specific, I'm going to try to use conductive paint to draw this circuit and I should be able to touch the circuit with a wire attached to a separate component and read the string. The "completely separate component" may be a number of different things I'll be making/programming to display/transmit that output, and each will do the work of converting the string into a format that it can use, so I want to keep everything outside of encoding a string in a circuit separate from this question if possible.

Does this make sense? What else can I say to clarify?

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#### BR-549

Joined Sep 22, 2013
4,938
"30 string character in the form of a circuit"

You mean a 30 char string. What do you mean by "form of circuit"? What characteristic of a circuit do you want the 30 char string to form?

Do you know how microprocessors and memory work? Do you understand how a string is moved thru memory and processor?

I'm not sure I understand what you want to do. What do you mean by touching wire, reading and formatting?

Are you trying to read a data line or something?

#### DarthNitpick

Joined Jan 24, 2018
8
It sounds like what I'm trying to do is read a data line, yes.

I just need to be able to represent an arbitrary but specific 30 character string in the form of a circuit that can be read out as data for other devices that will do the work of interpreting that string onto say a digital display, or into a waveform or whatever it may be.

I don't have a complete understanding of memory or microprocessors, but I first need to evaluate what solving this particular element would look like before I put a whole picture together. This circuit I'm trying to make doesn't need to be too clever or be able to output different strings, I'm really looking for the most blunt instrument solution!

#### LesJones

Joined Jan 8, 2017
2,696
Are these characters all part of the standard ASCII character set ? If so each character could be defined a 7 bit code. The best way I can think of to represent characters in a physical form would be a diode matrix of between 1 and 7 diodes to represent each character. Touching a wire to the common point of each diode group would give an output that would display that character on the display. I am assuming the display is a single character display as your description is still not very clear.

Les.

#### BR-549

Joined Sep 22, 2013
4,938
OK....I see what you mean. But, like I said it depends on the details.....and it really does. You just can't attach a connection and read the mail. Doesn't work that way. A string is a sequential list of information or data. The data in that list can have different electronic structures, called protocols.

This list can be assembled or dis-assembled one by one or in groups.

Strings can be represented with voltage levels, current levels or states.

A string can take 2 wires or 9 wires or many more wires. A string can take 2 volts, 3 volts, 5 volts, 12 volts.

It depends on the details. And a textbook to understand it all.

They do have logic probes and data monitors for digital circuits. I don't believe a simple circuit will suffice.

#### DarthNitpick

Joined Jan 24, 2018
8
@les: That's my understanding as well; ASCII, 7 bits per character (because I don't want to take any shortcuts, like if the same character is repeated in the string), but I need the display to show the full string at once.

@BR-549: Hmm, well, if I were to put it to you this way: How would you personally ideally create a module to output a fixed string of characters? I'm really pretty open to any insight or change in direction, given I just need to be able to isolate this string in the form of a circuit, and in such a way that I can make other things to read it. I understand you're saying those other things matter, but I'm sort of wondering why I wouldn't just be able to build intervening components that can convert this circuits output into other representations that would suit the particular usecase. Thanks for your help!

#### Sensacell

Joined Jun 19, 2012
2,595
Reading between the lines here...

Are you trying to make a gadget that displays a specific line of text when you touch a wire to a specific output (conductive paint lines)?

Like having "elements" that "emit" specific text strings along with separate "elements" that receive and display it?

#### DarthNitpick

Joined Jan 24, 2018
8
@Sensacell Exactly! But my challenge isn't the gadget, it's the circuit for the string.

#### MrChips

Joined Oct 2, 2009
21,820
Hello Darth,

So far your description/explanation/query is as clear as mud.
Do not attempt to describe it in electronics or circuit or computer terms because those have specific meaning for the audience here.

For example, what is a "string"? A string is a strand or thread, commonly made of cotton, which can be used for tying objects.

What are you trying to do?
Use everyday descriptive terms to describe what you are trying to achieve. Forget the possible solutions for the time being.
Are you looking at a printed page with text printed on the page?
Or are you writing using conductive paint on a piece of paper?

#### Sensacell

Joined Jun 19, 2012
2,595
@Sensacell Exactly! But my challenge isn't the gadget, it's the circuit for the string.
Ohh! why didn't you just say that!

Forget the techno-gobltygoop and just explain exactly what you want to accomplish in simple terms.
You will get lots more out of this using this strategy.

#### DarthNitpick

Joined Jan 24, 2018
8
Let me try again!

I want to draw a conductive paint circuit onto let's say paper and touch a device with a screen to it and have a specific phrase appear on the display. I'm not worried about the display side, I'm just trying to make that circuit read out a phrase.

Does that make sense?

#### MrChips

Joined Oct 2, 2009
21,820
Let me try again!

I want to draw a conductive paint circuit onto let's say paper and touch a device with a screen to it and have a specific phrase appear on the display. I'm not worried about the display side, I'm just trying to make that circuit read out a phrase.

Does that make sense?
No.

If you draw lines on a piece of paper, then try to touch the line with some kind of electrical probe (conductivity or voltage probe), you will get virtually the same reading along any point on the line. There will be no differentiating information at any point on the line.

#### ericgibbs

Joined Jan 29, 2010
10,752
Hi Darth,
You can buy paper with a conductive/resistive conducting backing, it is often used on Marine echo sounders.
E

#### LesJones

Joined Jan 8, 2017
2,696
This is my undestanding now. You have a piece of paper with drawing on it. You have box with a 40 character display on it. At this point the box has no connection to the paper. (You can leave the paper in one room and walk out of the bulding with the box. This statement is just to show how independent the two item are.) Am I right up to this point ? (The first point.) Second. There is a single wire or probe on the box that when touched on one of a number of features on the drawing give a text message on the dispaly on the box and the contents of that text message depend on what feature of the drawing that was touched ? (The second point.)
Now two questions. How many different text messages are there ? Also are the number of features on the drawing the same as the number of text messages ? Please give a clear answer (Yes or no) to point 1 and point 2 and also answer the two questions.

Les.

#### DarthNitpick

Joined Jan 24, 2018
8
@LesJones Correct on point 1 and point 2.

To your questions, (1) there is only one message I wish to show -- the full 30 character phrase. As for (2), I'm not sure I understand but given my answer to (1), I sense that is moot. The drawing is wholly dedicated to producing this single phrase.

#### MrChips

Joined Oct 2, 2009
21,820
So you have a drawing on paper drawn with conductive paint.
Then you touch any part of the line with a special probe.
What message do you want to appear on your display?

#### LesJones

Joined Jan 8, 2017
2,696
So could the display be as simple as for example the message in clear characters on a black film (Like photographic film) with LEDs behind it that illuminated when the message was required to be visible ? This would need to be behind a tinted screen so it could not be read without the LEDs being illuminated.

Les.