Tutorial #Electronica Basica. Cap 24. Hacer Insoladora con TIRAS LED

hello friends! We are going to give an advance to the issue of how to make printed circuits We already saw in this tutorial of basic electronics, in chapter 15, two methods to make printed circuits, the two most basic methods, One method was to use pre-printed circuit, either in the form of dots or in the form of copper strips, and is sold already pre-drilled with a distance of 1 / 10th of an inch between holes (normalized distance) This method is valid for very small and simple circuits For circuits a little more complex we saw the method of the marker which allows circuits with more components This method you have seen in many videos of this channel, so there are still two methods that are precisely the best: The thermal method or the ironing, and the method of exposure box that we are going to see in this video, or better Said: In these videos (because there will be two) If not, this video would be very long This first video is about how to make an exposure box because we can buy it, yes, but .

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They cost a lot of money.

And since we are electronic, we'll save a good money and we manufacture it ourselves So in this video we'll see how to build it I will talk about some components that have "surprise" like led strips And at the end of the video we are going to test this exposure box without going into details with the circuit, we will simply do that circuit to check that the exposure box works Will be in the second and next video where we will see details about the circuit, ignoring the exposure box since we are going to occupy of it in this video An exposure box is basically a box.

It may be this.

And inside .

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we will get out all these things Inside, on the floor of this box we are going to put ultraviolet lights occupying a certain area, and those lights will point out, upwards, so that If we put on this glass a thing called "layout" which is nothing more than the design of a printed circuit in a transparency eg acetate If we have laser printer, excellent.

If not, we can go to a copy shop with the file and print it for very little money By the way, where can we get a layout? The usual thing is that we do it with an electronic design program We can also get it from the Internet.

Many authors make it available.

I will, of course, from now on, I will put the layout at your disposal We leave the layout here, very important that the printed part, the part of the ink is facing up.

We'll see the reason for this And on the layout we will put the PCB, but this one that I have now in my hand is a normal PCB, those used in exposure box have on the copper a photosensitive emulsion, and are placed with that emulsion (and copper) looking down, towards the layout So that ultraviolet light passes through the transparent areas of the layout and impresses the photosensitive varnish of this printed circuit board But that light will not pass through the opaque areas, ie the printed circuit tracks The result is that the plate is impressed as in the photographic procedures When we close the lid we put weight so that there are no air bubbles between printed circuit board and layout.

Of course we'll have to align printed circuit and layout Now we would connect the exposure box (the ultraviolet lights turn on) and after a few minutes the light is switched off and the circuit is supposed to be already impressed.

From this moment we make a very simple process called fixing, we will use a liquid And then we'll act as with any other method of making printed circuit: With chemicals we'll attack copper to form the tracks Yes: You are right if you have thought that I will use this old scanner as a box for the exposure box.

I find it's a great option In a second-hand shop you can get it as cheap as five euros (that cost me), maybe cost seven, but surely less than ten euros What we are really interested in is just the box.

Everything inside does not work and we'll extract it: The metal guide, the timing belt .

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we'll leave it empty inside Well, what do we have here? For the moment, the box, which is enough.

We'll not have to buy or saw wood or join them together The crystal issue is also important.

Here it comes "serial".

Instead, if we make a wooden box we will have to get a glass and cut it to the measure (assuming we have tool to cut it, otherwise: visit the glassware) Another advantage is in this cover: This flexible material will serve to press the printed circuit against the layout.

In short, a great choice.

And also, the finish is also very nice.

So this will be my choice And what options do we have to produce that ultraviolet light? We have several: First, actinic tubes, are similar to short fluorescent lamps But generate a much larger amount of ultraviolet Its drawback is that they are quite expensive and their hours of life are counted.

This is not the option I am going to use Another similar option is black light bulbs, usually labeled "BL" (black light).

This lamp is like the one I used in the advanced anti-mosquito trap and serves for the exposure box But you should put at least three lamps Each of them can cost about 15 euros, so they are not cheap either And like actinic lamps, their hours of life are limited So I lean for LED technology In terms of LEDs we have two options: This typical led, emits in ultraviolet And we also have LED strip Which of the two did we choose? To this type of diode I see three drawbacks There are people who say they are delighted with their exposure box made with this type of diode.

I do not question it, of course.

But, as I said, I see three drawbacks.

First: to make an exposure box that makes circuits of a certain size, the circuit containing these diodes should be as large as that circuit we intend to do.

If I want to take advantage of all this surface (practically that of an A4 sheet) so I could make circuits as big as this Well, the diodes will have to be spread out on an equally large circuit.

If you have to put a LED every centimeter and a half, look at the large number of LEDs in a row, and then there are the columns.

We go easy to 200-300 LEDs The problem is not what LEDs cost, because this is sold on the Internet in large lots for little money.

The problem is that they need a printed circuit, whereas the LED strip does not need a printed circuit.

It is fixed with an adhesive that the strip itself has.

There is still more: Even if we use a circuit half as big as this, there are still many LEDs, say 120 LEDs.

Be prepared to do not 120 but 240 solderings.

The LED strip does not have to be soldered.

It's ready As if this were not enough, there is a third limitation that makes me choose the LED strip The third drawback of these LEDs is in regard to the opening of the light beam Here I have drawn several LEDs at a more or less real distance And we see that its opening is about 20º, this I have drawn carefully If I put the protractor here, in the center And the vertical is at 90º, we see that the beam opens 10 degrees on each side, about 20º in total There is an important shadow area, it is this volume from here.

All this volume barely receives light If we put a printed circuit at this distance from the LEDs, we see that there is light from here to here, and also from here to here.

But here there is no light, therefore, this strip will not receive light and the circuit will not be impressed in this area The circuit will be wrong We would have to set the circuit higher to make sure that light is going to be received in all areas If we position the circuit higher now a new problem arises: We now have direct light from here to here coming from this LED.

And from here to here coming from this other LED.

But this area is the sum of both lights Therefore, in this area, as there is more light, the sensitization process will develop more deeply and / or faster I do not know to what extent this will be correct, that's why I do not trust these LEDs.

In addition, the intersection of two LED light occurs at a fairly large height of about four centimeters At that distance you have to add the size of the LED itself, its terminals, printed circuit, soldering, a small separator and the bottom of the scanner, so we go to 8 centimeters, but the scanner is only 5 centimeters high.

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So we can not use a stylized box with this type of diodes, we would have to make an old design box All this will not happen with the diode strip.

Here I show a drawing And we see that the beam of light has a much greater angle, about 120º So the shadow space is now as small as this.

The neighbor LED intersects very low, a few millimeters in height (and not to 4 centimeters as before) And we make sure that the .

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1, 2, 3, 4, fifth LED to the right intersects a much lower distance than before and not 4 cms That is, in this zone we make sure that five LEDs on the right also reach with their light.

Also five LEDs on the left, five LEDs on there, and five LEDs on the other side (which I can not represent in a 2D drawing) Summarizing: Any point will be illuminated by a handful of LEDs, this will produce UNIFORM lighting, There is another problem: No matter how big you do the exposure box, there will be a problem that is as follows: I said to make the exposure box with a size capable of making circuits as big as this.

In practice they will be smaller.

Why do I oversize the exposure box? By this phenomenon: In a central area, for example here, this LED will have the support of the LEDs above, below, left and right.

And so, the whole central area And what about the edges? Edges are areas to avoid because they produce less light.

For example, here we have the support of the LEDs above, left and right, .

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but not the bottom (since they do not exist).

Therefore, the edges produce less light And that will cause the sensitization in the circuit will occur at less speed than in the central area that receives more light.

That's why I oversized the surface of the exposure box but then manufacture smaller printed circuits of course in the center of the available area of the exposure box.

We'll see the parameters of the LED strip that I bought in case you want to make the exposure box exactly the same I will also comment on the variations that can have those parameters in case you want to do something slightly different First: Where to buy it? I have been advised to buy it in a store.

It's going to be that not.

In a good electronics store there are LED strips .

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but colored, or white, but not ultraviolet that seems to be sold a lot less So I said to myself: Well, I'm going to order online, in any of the many online stores that exist, and have a lot of models of ultraviolet LED strips Price: Well, ultraviolet is expensive, I warn you from the beginning This strip of five meters cost me 45 euros including shipping, and delivery was very fast, only two days.

Other sellers were somewhat cheaper but took a long time to make the delivery according to their website I say this in case someone comments: "You have been cheated, I bought a strip of LED of five meters and cost me only 12 euros" Okay.

But white, green, blue .

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the ultraviolet, I repeat, is not cheap Another parameter, the length, I have chosen it of 5 meters.

I will use almost 5 meters to do this exposure box There are vendors that offer the option of 1, 2, 3, 4 .

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meters, but most of them offer 1 or 5 meters How many LED's per meter? We have two options: 60 LEDs per meter, and 120 LEDs.

I chose this last option, 120 Why 120 and not 60? Because having more points of light, it will diffuse and distribute better There are also LED measurements.

There are many measurements, but for ultraviolet LED strips mostly there are two sizes 3528 and 5050, these are the measurements in millimeters.

For example, my choice is the 3528, it means that the led measures 3.

5 x 2.

8 mm As for the 5050, it measures 5 x 5 mm, and generates much more light, up to three times more than the 3528, but also consumes more and the LED itself is more expensive, so my final choice is 3528 Operating voltage.

There are also two options: 12 and 24 volts.

I chose 12 V Power and current.

We will see this more closely because there is a "trap" here.

The power of the 5 meter strip I bought is 48W therefore at 12 volts, the current will be 4 amp Wavelength, very important parameter.

Well, if it says that it is ultraviolet that is already valid, but some vendor specifies it: Between 395 and 405 nanometers Below 400 nm is already considered ultraviolet, and above 400 nm is violet, visible light.

So, with its 395 nm, even by little, this emits ultraviolet radiation The angle of the light beam is 120º, there is no option here, I have not seen other values than 120º The degree of protection of the LED strip, you will see that in the announcement of the article are the abbreviations IP, that is the degree of protection and consists of two numbers, the first is protection against solids (dust and dirt) The minimum is a zero meaning "unprotected" and the maximum is a six.

The strip I bought is IP65 so it has the maximum protection against solids.

The second number is protection against liquids and moisture.

It is from zero (minimum protection) to eight (maximum).

My LED strip is "five", and according to the table corresponds to withstand water jets, which I think the exposure box will never have to face A few moments ago I commented that there was "trap" in terms of consumption, the current effectively, I bought a first strip of LED, 5 meters and 24 Watts 24 W at 12 volts are 2 amps The first thing I did when I received the LED strip was to test it, measure the current, and 2 amps .

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nothing.

I got 0.

4 amps, one-fifth.

I thought: Some part of the strip will have broken and that's why it does not work as it should.

That was not the case.

It was fine, so I gave it back On another website, to another seller, I bought another LED strip, this strip.

Also 5 meters but 48 Watts so now would be 4 amps The same thing happened to me again.

Instead of 4 amps circulated 1.

2 amps, practically a quarter.

That's when you think: I do not think everyone is cheating on me.

Here is something happening that escapes me After researching a little I saw that these LED strips are very curious.

They have a tremendous voltage drop even though they are only five meters.

Now you're going to see it By the way, in this reel there were 5 meters, now there are 4 because I took a meter, nothing happens, we do proportionality: If instead of 5 meters there are 4, instead of 48W will be 38.

4W, and instead of 4 amps, It will be 3.

2 amps I have this tester measuring the voltage that comes from a power supply, a correct voltage, approximately 12.

11 volts, in a moment I will connect it This tester will measure the current consumed by the LED strip, which current is now zero And this third tester will measure the voltage .

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but at the end of the strip, not at the beginning.

Okay, I connect .

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It lights up, I hide the light so the camera will not do anything strange And we have: the voltage at the input went down from 12.

11 to 10.

80 volts.

He's down a lot.

But at the opposite end of the LED strip there are two minus volts As for the current, nothing 3.

2 amps.

There are only 0.

9 amps.

Almost an ampere, is the third part of what should circulate the consequence of this is that the power is three times less than advertised The worst thing is that the lower power is irregular: At the beginning of the LED strip more illumination, as you move towards the end of the strip, less light, and that does not suit the exposure box.

We want a lighting as regular as possible Well, we're going to solve this In this drawing are the two solutions that we are going to adopt As for the voltage drop, so we connected the LED strip before.

And so we will connect now: Not with 12 volts, but with 13.

The LED strip is not going to happen anything because a battery at full load are not 12 but 13.

2 volts The strip is not going to break for that volt of more, but that volt will produce a current increase of 100%, now will pass two amps, not one, therefore the power will also be double In addition, the LED strip can be supplied with power at one end, at another .

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and at both ends.

We will connect it at both ends respecting the polarity of course Let's assume that this right side is the positive (LED anode), it will be along the ALL LED strip With this resource we'll decrease the voltage drop and we'll see that the current increases even more By the way, what power supply are we going to use? This is the power supply that I will use to make the exposure box work.

I bought it in a store, it's a fairly standard, switched type model.

That's why it's so small despite delivering more than 2 amps This power supply has here a insert, can be set and removed, This power supply carries with it a lot of those parts with which you can get all these voltages to these currents In the upper part of this table you will see that it puts: 13 volts, 2.

40 amps.

That is the value that I have chosen Also includes this power supply a lot of pins, this one that I have already placed in the cable, I have made sure that it fits with the power outlet of the scanner, facilitating the subject of the electrical connection Here we have the assembly to test this 13 volt power supply .

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Look at the detail that the power of this end also connects it to the other end of the LED strip For now these cables have not connected them yet.

I'm going to connect The tester that measures the current no longer marks 0.

9 amps but double: 2 amps.

That, only thanks to a volt of more Now I will connect the power also to the other end of the LED strip, let's see if the current grows Rises to almost 2.

3 amps, we have managed to increase the current.

If we multiply the voltage by the current we see that we have almost 30 Watt.

This is already much better So far we have seen the most theoretical and important parts of the components.

Let's go to the assembly of the exposure box List of components.

If I do not forget anything, there are only four things: the box, that is, the scanner, the LED strip, a little cable to connect the pieces of LED strip together since we can not put it in a piece, now We'll see why And an adequate power supply As I said at the beginning, we are going to remove from this scanner everything that does not serve us, the lid is easy to remove, it is already loose.

We are going to remove this, also this motor that only adds weight .

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The pulley and the belt, this piece from here .

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Of the power supply we are going to leave only the input plug that I have already checked that is valid for the external power supply that we are going to use This small power supply from the scanner we remove or ignore it.

We will pull the cables to the LED strips directly Also this plate of here .

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we are removing everything that does not serve And leave the inside clear to place the LED strips on the scanner floor Once we have measured a piece of strip to 30 centimeters (centimeter more, centimeter less), we have to look for this symbol that you see in the center of the image, a pair of scissors and a line.

For that line is where we have to cut the strip We will not cut anywhere else.

The strip is full of areas like that, see? Slightly to the left there is another symbol of scissors.

Every three LEDs there is a cutting zone We also see four circles: They are soldering points once we cut the strip out there These points can be joined with cables, soldering them in a normal way If we have to cut, we will do for this area, not here in the middle, we would leave this section of three LEDs unusable Before removing this protective paper and gluing the strip to the bottom of the scanner, I recommend removing at each end this protective plastic that is very well appreciated, has an appreciable thickness, either with the nails or with an x-act to be able to then solder these circles and join the pieces of strips If we intend to remove this plastic while the strip stuck to the bottom of the scanner is going to cost a lot of work.

Better to do it now I have already drawn all these lines that will serve as reference to put the strips of LEDs We have these two marks 300 mm apart, and there are 15 lines as if they were lanes.

There we are going to put a strip in each line, cut to 300 mm of length And why 300 mm? And why 15 strips? 300 mm because it corresponds to the length of this window Being the width of 210 mm, there is room to put these 15 lines and go putting LED strips and cover those 210 mm So that 300 mm each of the 15 strips add up to 4500 mm, that is, four and a half meters, so that half a meter of the strip of 5 meters is reserved for prudence if necessary The first thing we are going to do is cut strips to 300 mm long, I see that this strip measures a little more, it has three LEDs over So I will use it to cut that leftover piece and we will see how and where the LED strip is cut Well, the strip cut to size, the protective plastic removed at the end, we are removing the adhesive protector .

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We put the strip well centered .

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We press a little, and it is well fixed We do the same operation for the remaining 14 strips of LED Well, with patience, one by one, put the fifteen strips Now we are going to join with two cables each end of a strip with the beginning of the other strip Then, this, we join with the next, and so, we go zig-zag like a serpent, until the end The cable to be used for this should not be too thin to avoid voltage drop, a copper thickness of 1.

5 mm is fine This cable has the silicone-based sheath, it is very flexible, it is not tense, it is suitable because it will not force the LED strips.

Red and black cable, to maintain polarity By the way, speaking of polarity, you can put the LED strip this way .

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or so, when it is working is indistinct, but you have to be careful with this because the LED strips have a polarity on one side and another polarity on the other side Therefore, we connect the positive with the positive, and the negative with the negative If we put the strips of LED at random, that must be taken into account because we will surely connect some of them incorrectly.

if we do not pay attention.

It will not break anything if we connect a strip with the reverse polarity The strips do not break because of that, but they will not work with the current inverted, and it should not be stressing the strips with solderings I'm going to select a closer video recording and I'm going to solder these two first cables, which are already tinned positive.

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This end, to the positive of the other strip of LEDs We will do the same for the negative pole with the black wire, from here to here All the cable jumpers are already on, right and left, with the power at this end I already said my intention to put the power also in the other end to combat the voltage drop and that the LEDs shine more.

Now I will put those two power cables for this end It can happen that in some of these strips some LED fails, although the normal thing is that they break in groups of three LEDs I've been lucky, that has not happened to me.

But in the half meter of strip that has left, it has happened.

If that happens to you here in the scanner, cut and remove the defective piece, you take a piece equal to the half meter of strip left over and solder it here We are going to connect the power supply to prove this.

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We have .

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for now, a voltage of 12 volts and a consumption of just over 1 amp, which represents about 16W (may be worth it) but I will go up to 13 volts .

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And the current rises to practically two amps When we put the power also at this end, The current will rise to two and a half amps Which multiplied by 13 volts are about 30 W which I think is pretty good We are going to prove one important thing: The diffusion of the light, that is to say, if this will illuminate the PCB evenly or otherwise there will be areas of light and shadow We are going to put a sheet of paper resting on the LEDs and we see that there are areas of intense light and shadow areas but no one is going to put a PCB just above the LEDs We will raise the paper a little and we will see that the light is now diffused What do you think? The illumination is now completely uniform, you do not need a diffuser.

This system of LEDs already has diffusion by itself At a distance of a few mm and the light is diffuse.

I'm going to turn off the light to see if it looks better .

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Now you can clearly see the light points of each LED .

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and when you raise the paper a little the points disappear and you see a uniform and diffused illumination There is very little left to do here.

I have put the two wires to feed the LED strip at the other end Here I put a printed circuit board as a junction box as there are six cables: Two from here, two from the other end of the LED strip and the two wires from the power supply By the way, the small circuit of the power supply that had the scanner I'm going to take advantage of, that better than to take out the pin and paste it here anyway This I see the best.

I had to make a drill to override a pad (this circuit has tracks on both sides) I don't want the tension that I'm going to put here go to this source.

I'll draw that voltage for the LED strips using two wires I'm going to put the power supply here in its place, with its two screws .

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Now we can connect the true power supply that is this I'm going to solder the wires.

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The positive pole, we're going to solder it here The negative pole, here Now we solder the wires of this end of the LED strip In this small printed circuit I have put a large tin cord to not connect the three wires of each pole at the same point I'll solder the negative pole, .

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here Before connecting the cables of the other end of the strip we are going to prove that this works, the power supply is plugged .

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I connect.

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very well Now solder the two wires of this end of the LED strip Now the positive .

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Okay, let's try it again .

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great.

Let's cover it Exposure box is ready.

I'm going to connect it.

I put the lid in place .

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If I put a paper there are no highlights.

The lighting is completely uniform Now we are going to test the required exposure time.

I'm going to make a real PCB I'll make a PCB from start to finish I'll test the three phases: exposure, fixing and etching Regarding the first phase, exposure, the most important thing is to determine the time that this exposure box needs, which I do not know because .

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I just manufactured it There is a minimum exposure time to be overcome, and a maximum time that we must not exceed The exposure time is rather a time frame than a specific time It is very important that the layout is opaque in the area "tracks" precisely so that the light does not pass to the "tracks" zone The less quality has the layout, the narrower will be the valid time margin for the exposure box, arriving the case where we can not use that layout because it is too transparent After the exposure phase of the PCB to the ultraviolet we can have three results that will be revealed in the following operation, the fixing First, short exposure: In the fixing process, the area that has received light and that should be detached from the photosensitive layer, does not detach.

Much less will be detached in an area of the PCB protected by the tracks of the layout The next possibility is a correct exposure time.

In areas of the PCB that have received light will be copper in sight.

But that will not happen in areas protected by the tracks of the layout And the third possibility is an excessive exposure time, as I say, this is not easy to happen if the layout is of very opaque quality In the case that we are passing of time we'll see that the photosensitive layer of the areas that have received light detaches .

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but also will be detached of the zones corresponding to the tracks This may be a partial defect, we will see that the tracks are weakened, very thin or shredded, or it may be so extreme that all the photosensitive varnish will disappear, leaving ALL copper in sight Well .

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I don't know the time that I'll need, but with the information I have, in addition, years ago I had an exposure box.

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I estimate to use an initial time of five minutes, to see what happens .

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I'm going to use this layout, do not ask me what circuit it is, I have no idea .

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I found it on the internet and liked it because it has very opaque tracks So I downloaded it, I printed it on an acetate, and this will be the layout I'm going to use I will not give much information in this video about the process of making the PCB, that I will do in the next video where I will talk about making a PCB with this method.

I'll just say one thing: This is printed on one side.

We have to know which face is the one containing the ink.

The printed side, which contains the ink, should look up.

Very important this detail And on the side of the layout that contains the ink we will put the PCB with the face containing the copper and the photosensitive coating down, facing the layout I'll put the layout in the exposure box I have turned off some lights so I do not have much ultraviolet level here put the layout with the ink facing up and on the layout I'll put the board which I'll show a few seconds I don't want it to be printed with light.

I've removed the wrapper and it looks dark we placed the board centered on the layout .

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we close and put a weight to avoid air bubbles between the board and the layout we turn on the exposure box this is the object that I'm going to place to exert pressure and avoid air between board and layout Why a timer having a cell phone with a stopwatch? We turn it on.

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is on .

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yes.

We started the countdown .

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about to complete the five minutes of exposure we turned off the exposure box .

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I'll save the board while preparing the material for the fixing process .

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in this box, well protected from light here, all the material necessary for the fixing process.

In this container I will put the fixing liquid that is simply water (250 cc will be sufficient for this board).

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and in this water will dissolve 3 g of caustic soda (also known as sodium hydroxide) the sodium hydroxide is caustic, it is corrosive, I advise to use protection: gloves, glasses, and if we splash, we must rinse with water immediately I will dissolve those 3 grs of sodium hydroxide in these 250cc of water, ie the ratio is 12 grams per liter of water then put the board in this solution to carry out the fixing process and then rinse the board in this container containing water alone we'll have a sponge prepared in case you have to rub the board and a fork or something similar to take the sodium hydroxide.

Always use plastic or wood tools, never metal to handle caustic soda.

I'm going to measure (weigh) the caustic soda I put this paper as tray or container, I zero the scale .

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this caustic soda is in pearls, it is my preferred format we will measure 3 grams .

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this has to be done fast because.

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atmospheric humidity spoils caustic soda 3.

3 grams, you do not need to be meticulously exact on this occasion we threw it into the water I don't know if the camera has captured it, caustic soda is here I'll dissolve it .

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the caustic soda bottle must be closed as soon as possible: It is damaged by the humidity of the air we dissolve when I pour this content here, I will have to work in low light, or better yet, red light.

I will turn off the ceiling fluorescents, otherwise I can ruin the PCB with ultraviolet the caustic soda is already completely dissolved .

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pour it into the container and now you're going to let me put on another lighting .

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not to spoil the board with this red light I hope it looks more or less the process we submerged the board already impressed with the face of copper looking up let's shake the bucket so that the liquid is distributed and acts better tracks should start appearing within 30-60 seconds first attempt: total failure.

The enamel has not been detached in the exposed areas in the exposure box I'll try again, with a new board, now with 12 minutes of exposure box remember: The side of the photosensitive varnish, upwards we have to gently shake the tray .

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I see the tracks, I do not know if the camera will appreciate it .

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when copper appears, it is time to stop and rinse the board I think it's ready we rinse it with water .

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if we think we are short of time, we put it back into the bucket of the fixing I think it's okay.

We proceed to the following process: Etching with acids While preparing the acids I will keep the board in a dark place.

It is still vulnerable to ultraviolet light.

It is okay if we dry the board with a paper napkin, the "tracks" do not come off.

let's go etching process, I will continue with the red light, because unlike other methods of processing PCB, ultraviolet light can ruin the process here are the chemicals you already know (Chapter 15 basic electronic tutorial) hydrogen peroxide, hydrochloric acid and water here is water with a little sodium bicarbonate to neutralize the acid action when we take out and rinse the board.

Let's proceed .

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put the board with the circuit up, and shake the tray when the copper that has to come off comes off, we take the board ready we stop the action .

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of the acid .

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we brush a little I think it went quite well.

Let's look at it with normal light There is.

Well, the photosensitive varnish should be removed with acetone or alcohol, which is no longer necessary.

The copper will be exposed.

What we said: we are going to remove this varnish.

We can use acetone or alcohol, I will try with acetone, pour a few drops on a kitchen paper or napkin .

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It comes out very well, you can see the color of copper The truth is, I'm pleasantly surprised that, on the second try, it worked out so well I'll take more paper to finish cleaning .

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And this is the result despite being so thin tracks, look really good.

So the power circuits with thicker tracks will have no problem we are coming to the end of this video, I do not want to say goodbye without mentioning my blog, the blog "100ciaencasa" Not all, but most of my videos have related an article in that blog For example, in this same video "how to make an exposure box", under this window, you will see "Blog .

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and a link".

Well that link talks about this video with photos and material that I do not show in this video, and such info can be very useful I say this because many, many people (but many) ask me: Where can I find the scheme, or the plans? .

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all that is on the blog if you click that link, you will not have to search the article on my blog.

It leads you directly to that article.

And that in every video.

of course, you can see from the same blog any article that interests you.

To this day there are (I think) about 124 articles if you decide to enter the blog is possible (especially if you have activated the AdBlock) you get a "nice" message that asks you to disable AdBlock and is that, surviving on the Net every day is more difficult because .

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the youtube partner is becoming less and less Other youtube channels may not .

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but mine asks for money to do things, (and more that I would like to do).

So.

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I dare to ask you to deactivate AdBlock when you see my videos or blog, and do not take it wrong in the end, blogspot is a fairly innocent environment in terms of advertising, is not aggressive and yes very discreet.

An ad appears to the right and a banner below, and that does not bother at all YouTube itself may be a bit more annoying with those ads that you have to wait 5 seconds, but you can not imagine how much it helps us to put us on a whitelist in AdBlock because .

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you can disable AdBlock in two ways.

I do not ask you to remove it, only to disable it momentarily when you go to see my content, or better yet: Add me to a white list (Exceptions sites in AdBlock) Now yes, I say goodbye.

See you in the next video.

Bye.

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