This arrangement is quite simple, we take the opportunity to see how we can ourselves imagine and build his own prototype ....
I / Theoretical or performance of the scheme
1 / The idea
The idea is simple: to light up an LED when a telephone is unplugged 2 / knowledge to have
Our installation will be connected to the telephone. We must have some knowledge on this subject: => It runs in the telephone, direct current. So there is a "plus" and "minus"
=> This polarity is reversed as is known, or that one is called (the + fates can - and vice versa)
3 / Preliminary Studies
We begin by considering what properties of the telephone. For this, we need a voltmeter (or multimeter voltmeter in position), position on the largest size available. When you look inside a phone jack, you can see it has 6, see 8-pin. The thing is to determine the positive pole (the "plus") the negative pole (the "minus").
So we will survey the pins one by one. To start with the black wire (which is connected to the "least" of the voltmeter) on the top left, and begin to move the red wire (the one linked to above). We begin by putting it in the top right. Looking at the voltmeter: It indicates 0V.
Turning left at the second pin from the top .... Takes! This time, the voltmeter indicates - 50 volts (plus or minus 2V or 3V). Here we have a negative voltage.
Invert the red and black one obtains about 50 volts. We just determine where the "plus" (top left) the "minus" (just below). Pick up the phone ... We see the tension rise to about 25/27 Volts.
We have just learned that the voltage on these terminals Moitiers decreased when the phone is off hook. All this will be to detect the voltage drop ...
5 / First sketches
Here we are with this. But the voltage across the phone is 50Volts. But we can not send 50Volts at the entrance of the gate, it would destroy the ... We have 15 volts at most, 10 volts for a margin ...
So we will reduce the tension with a voltage divider bridge.
We obtain the following diagram:
It's better ... But we learned that the Polarity of the telephone line changes depending on which is called when one is called. But if the "+" becomes "-" we will have a negative voltage to the input of the NAND gate. It is imperative to always have a positive voltage.
How? But all simply by adding a voltage rectifier bridge.
We will make this bridge with 4 diodes.
So we get this:
It is already much better ... But we will finish it completely ...
Indeed, we must ensure that the input voltage is perfectly smooth and clean.
For this, we will add two capacitors that are responsible for sending a mass all parasites. We will put a first capacitor before the diode bridge. This one will obviously not be biased ... and we will make a second after it, for against, is biased ...
We find this:
Perfect. This time, our editing is finished ...
Done? It is food yet ...
How to feed our assembly?
The simplest and least dangerous is the use of an electric battery.
What value does the battery last? Let's see ... A CMOS logic gate (the most common type) as used here must be powered from 5 to 15 volts. so we can not use the battery of 1.5 volts or 4.5 volts ... is the 9 volt battery.
So we get this pattern:
It takes the form, right? Well, one major problem of battery: it wears ... And when a battery wears out, its voltage decreases. The battery will therefore go from 9V 8V 7V etc. then ...
But it is very dangerous:! Indeed, remember the course on logic circuits: THE POWER SUPPLY MUST NEVER BE LESS THAN THE INPUT VOLTAGE.
But that is what will happen if the battery wears out: the power supply (battery) decreases, but the input voltage (phone) remains constant. Food and losque U <U input NOR gate is destroyed! Therefore a diet that provides tension relief and never wears out ... Use the phone!
This is achieved:
Second problem: If we do that, we obtain a power of 50 or 27 volts on the gate (from phone). However, the maximum voltage of the power supply should be 15 volts. it is necessary to reduce this tension. So we will use resistance. For reasons of aesthetics and symmetry, we will put one in right after each pin (we could put them in a row, or only to an equivalent value, but it is not very aesthetic, not symmetrical because ...)
We get this:
Then we will make a final filtration to remove all parasites:
Indeed, the current leaves the battery charges the capacitor, powers the logic ... But continuing its "path" to get through the resistance and added to the input voltage ...
We must prevent this ... With the help of a small diode.
It was therefore this:
6 / Diagram final
This time, our assembly is TER-MI-BORN!
It remains for us to give names (C 1, R 1 ... etc.) components.
We have:
7 / The value of components
It remains to find the values of the components ... Nothing to help us, we can already say:
> CI 1, the gate will be CMOS type, in the series of 4000. I suggest the 4069, which includes six inverters alone. (Of course, we will use only one).
> D2 to D6. There are diodes capable of handling several amperes. To the extent that the current flowing in the telephone cable is of the order of microamperes, and the stack 20 or 30 mA maximum, we do not need to use diodes that support 6A!.
So our choice will be the 1N4148 diodes. These diodes support up to 75 mA (which leaves a margin) to 100V (two times the voltage on the telephone cables, which, again, leaves us a margin).
=> About the diodes, but also other components such as capacitors, always a component whose voltage and current, borne up's bigger than the tension and intensity of use, so as not to " toast "because the component has a peak voltage or current ...
And if you work in AC, multiply by two the maximum voltage (= voltage times given root of 2): For when one says "220 Volts AC," it means:
1 / "220 Volts effective,"
2 / Thus, "311 volt maximum voltage (220 x 311 =
) " 3 / but "311 volts zero point at the top of the ridge"
4 / and thus by conséquant, "322Volts peak to peak" ...
> The LED D1 will be a red LED 3mm in diameter.
> C1 should not be polarized, and must have an operating voltage above 50 volts. The choice becomes clearer after Tuva value.
> C2 and C3 must be polarized: we choose capacitors chemical (or "electrolyte")
Now, get out your software!
Indeed, we will proceed by trial and error to set the value of resistors, capacitors etc ... It's not very scientific, but we have no choice ... Why? Because, with respect to the calculation of resistance, we should know the strength that is in the son's phone. Now, all we know is that this intensity is only a few microamperes (1/1000000è amps). If you do not have an ammeter capable of measuring microamps, you can not measure this intensity, and even if you own a microammeter, I advise you not to perform this action. Indeed, an ammeter acts like an electrical wire. You may then cause a short circuit and destroy the phone line ...
But we can not proceed by trial and error with real components in order not to risk destroying them, or destroy the phone line by taking low resistance ... (how would you go to see my web site ? :-))
So we will use simulation software.
The best known is Pspice. offers many sites are downloading (and I would soon go ...) A DOS version (2 MB for version 6.1) or Windows (13 MB for version 7.1). For now, let us remember the following address: http://corn.eng.buffalo.edu/ece202/pspice.html .
You can also choose Proteus Lite downloadable http://www.multipower-fr.com/sharewares.htm .
While Pspice give you output curves, as on an oscilloscope, Proteus uses the simulation: you see, for example, the LED light up, input and output of IC 1 goes from 1 to 0 etc ...
Of course, these two logicels speak the language of Bill Gates ...
To get an idea of current flowing through the phone line, we can measure this current by including a resistor in series. to be safe, take a BIG resistance, for example, M 10 W
We see that we must tell the software a current between 10 and 20 microamperes.
After several trials, we find:
> R1 = R2 = 3, M 3 W
> R3 = 470 W
> R4 = 2, M 2 W
> R5 = 636, W 7 K
> C1 = 220 nF => Value, it could take MKS or "plastic", "Milfeuil" or "Mylar"
> C2 = 100 m F
> C3 = 2, m 2 F
We will now replace the logic gate NO, we had found in the theory, for a quadruple NOR gate:
Several reasons for this change:
1 / Ideally, the assembly works with the NAND gate 4069, but the prototype PhoneLampe I have at home uses 4001, quadruple NOR gate. As I want to make sure you have an operation, I will make available the version I have at home ... (more the 4001 is cheaper than the 4069 ...)
2 / This allows us to study the rating of Hi-Fi separates when there are several logical functions:
Observe the gate U1: A is added, B, C or D.
When you see U1: A, U1: B etc, you are sure you are dealing with a number of logic gates in the same integrated circuit, whereas if you have U1 and U2, these are two different boxes, even if it is two doors NOR ...
Note that the gates C and D have their outputs are connected. We can connect two output under the following conditions:
- That the doors are of the same technology (you can connect two output CMOS, TTL or two, but not a CMOS output and a TTL output ...)
- What are the outputs in the same state at the same time: here is the case since their inputs are connected: if the entries in the D gates are 1, those of the door are also C 1 .. .
Connecting two outputs and allows a double power: the power that comes from the door C over that of the door D. LED shines more ...
3 / Note that when a NOR gate has its inputs connected together, it behaves like a NAND gate.
4 / Finally, notice that there is number of input pins and output of integrated circuits, in order to facilitate the achievement ...
Note that we add R6, R7 and R8 in Parallel with R5, in order to get a group of 636 who raproche, W K 7.
Finally, notice that we added an eighth diode: the diode D8. I could tell you why it's there, but it is complicated - so not for this site, and it is not easy to explain, especially to explain like this, virtually ... :-)
This diode is a 1N4148
8 / Nomenclature of components Here are the final scheme with the nomenclature of the components:
| BAT 1 | 9V |
| C1 | MKS 220nF capacitor |
| C2 | Chemical capacitor 100 m F |
| C3 | Chemical capacitor 2, 2 m F |
| D1 | Red LED 3 millimeters |
| D2 | 1N4148 |
| D3 | 1N4148 |
| D4 | 1N4148 |
| D5 | 1N4148 |
| D6 | 1N4148 |
| D7 | 1N4148 |
| IC1 | CMOS Circuit 4001 |
| J1 | By jack |
| J2 | By jack |
| R1 | ½ watt resistor 3.3 M W |
| R2 | ½ watt resistor 3.3 M W |
| R3 | ¼ W resistor 470 Watts |
| R4 | ¼ watt resistor 2.2 M W |
| R5 | Resistance ¼ M Watts 10 W |
| R6 | ¼ watt resistor 680 W K |
| R7 | ¼ watt resistor 330 W K |
| R8 | ¼ watt resistor 560 W K |
Notice that the diode bridge we greatly facilitates things. Indeed, it is not worth breaking the head by asking the question "Where is the + telephone". You can reverse the "+" and "-", the diodes rectify things! For information, here are the pinouts of the integrated circuit 4001:
Take this opportunity to note that pin 1 is left of the mark if you look at the circuit from the rear (the side opposite the mark) ...
II / Practical part, or the prototype
Indeed, I found sites that offered packages gave the design of printed circuit ... That's good, but everyone can not afford to make a printed circuit board:
1 - need software for the design of the CI
2 - It must be material: transparent sheets, insolation, etc. printmaker ... And all this is expensive and not for a budget of electronics amateur.
We will, however, how to make his print circuits on a small budget, but to make it profitable, you must make arrangements regularly, and often ...
We'll start by studying a prototype when making arrangements occasionally, ie, the realization of wafer punched tape.
1 / Completion of booklet has punched tape
Platelets has perforated strips ... What a wonderful tool for those who made arrangements occasionally.
These pads Bakelite, an insulating material, which have, on one side, brass bands separated by a few millimeters.
These plates are already drilled at 2.54 mm pitch. What is not? This is the distance between two legs of a component. The standard is 2.54 mm and its multiple, or 5.08 mm, 7.62 mm etc ... These plates are perfect for montages.
It has however one drawback: When you do not want an affair, it is necessary to cut the copper strip and, in payment when you want to connect two copper strips, one is forced to use "straps "which are simply small pieces of son ...
This represents more than welds, but no drilling, which is very advantageous (you see all the 2.54 mm drill you?)
Before going further, let's see what we need:
| 1 | MKS 220nF capacitor |
| 1 | Chemical capacitor 100 m F |
| 1 | Chemical capacitor 2, 2 m F |
Carbon Film Resistors
| 2 | ½ watt resistor 3.3 M W |
| 1 | ¼ W resistor 470 Watts |
| 1 | ¼ watt resistor 2.2 M W |
| 1 | Resistance ¼ M Watts 10 W |
| 2 | ¼ watt resistors 330 W K |
| 1 | ¼ watt resistor 560 W K |
semiconductor
| 1 | Red LED 3 mm |
| 7 | 1N4148 diodes |
| 1 | CMOS Circuit 4001 |
Various
| 1 | 9 volt battery connector |
| 1 | Phone plug pullout |
| 1 | Bakelite plate was perforated strips minimum size 22 rows x 32 columns |
| 1 | Integrated circuit support 14 feet (or 2 x 7 feet) |
| / / | small pieces of wire |
| / / | Telephone cable 2 (or 4 if there is no 2) drivers |
Let's start by cutting a piece of plate: you have 22 lines of 32 columns.
Then you have to make a mark by numbering the rows of A to V and the columns from 1 to 32.
Then, cut the copper strips:
Cut to:
| E13 | E14 |
| F13 | F14 |
| G13 | G14 |
| H13 | H14 |
| J13 | J14 |
| K13 | K14 |
| R8 | R9 |
| T25 | E19 |
| F19 | G19 |
| I19 | J19 |
| K20 | F28 |
| F29 | J28 |
| J29 | /////// |
Take a forest of 2 or 3 millimeters and made him two or three laps by pressing too hard (might break the plate). Then make sure the eye as the track is cut, possibly, use a multimeter ohmmeter position on the smallest size (It should be displaying "1" to the left of the screen). If necessary, iron the forest. Use either the hand or a drill. But in this case, do not turn the forest too fast! After cutting the tracks, go to the board layout.
Return the plate. Note that the coordinates are reversed along the axis horizontal. Thus, one is left and 32 right, but A is low and V high ...
Start by placing the straps that are represented here by simple black line, blue or red. Use small pieces of bare or insulated son. the son of course, avoid isolated short-circuit and it is the latter that I advise you to use. When you have two line one after the other to connect, as it is to the right of U1, you can replace the straps by welding directly behind.
Then solder the resistors and diodes. If the resistors are numbered so that you recognize, this is not the case of diodes (with the exception of the LED D1) because they are all 1N4148. Simply pay attention to their senses. Notice that the cathode, symbolized by a black ring, is always directed to the A line, with the exception of the diode which is after the battery and has its cathode to column 1. One of the legs of R3 is hidden by the capacitor C2. The study su scheme will allow you to conclude that this tab is on the same line as the leg of C2, ie, line G. The same applies to one end of a strap that is hidden by C2 and C3, which is on the line E.
Solder then the capacitor. Attention C2 and C3 which are polarized!. The "+" must be directed to the line A, therefore, the leg indicated by the arrow "-" should be directed to the line V
Finally, weld the support of U1 to its location, BUT DO NOT SET YET U1.
Then solder the LED. Remember that the cathode of the LED is the shorter leg. This is the shorter: it is connected to the minus (row O). the anode, the longer leg is on the line N. Of course, you can not solder the LEDs directly on the plate and use of small diameter wire (1 mm) to make the connection ... Solder the last son of the stack and those that will connect the phone at the other end to an adapter plug (connection to the EXT following cons). If you reverse J1 and J2, that's OK: The diode bridge D1-D2-D3-D4 rectify ...
Finally, solder the 9V battery connector. Do not mix son: Red wire from the connector on the rod T, Black wire on the line O. .. Then take a voltmeter to a size between 5V and 20V. Place the probe "+" (red) line F, at the foot of R4, and the point of "-" button (blue) on the circuit ground, ie, the level of "less" of the stack (line O), for example, to the cathode of the LED.
With ALL phones on hook (including modem), you should be between 4-6 volts and 9 volts (but certainly not greater than 9 volts). Pick up a phone: the voltage must fall between 0 and 2.7 Volts.
These two conditions are met? Then, disconnect the telephone installation, remove the battery and place U1. Be careful: the mark of U1 should be directed to the line V.
Reconnect battery and phone and repeat the tests: the LED should light up only if the phone is off hook. Got it? So it remains for you to put your mounting box ... (Non-metallic box of course ...)
II / Achievement PCB
1 / Have materials
You will need:
- A copper plate coated on one side
- From perchorure iron (granules dissolve or bottled)
- 1 container (especially not metal! It would be dissolved by the perchloric!)
- Felt a normal
Optional:
- Felt a special Dalo 33 (more resistant to ferric chloride as a felt normal)
- 1 + pencil eraser (the IC to draw on the plate before doing the felt)
- From stain for ferric chloride
- Copper films (for repairs of tracks)
Replacing the felt, and what is better:
- Sticky pellets that resist ferric chloride
- Self-adhesive tracks which, together, are resistant to ferric chloride
And of course, you need components, the soldering iron and solder ...
Finally, a board before you begin:
Work with a gown and gloves! (The perchloric, it stains a lot)
2 / Draw To draw a CI CI is based on the scheme. Here, the pattern is this:
But the four NOR gates are integrated into a single housing with a pin is this:
Note that we have connected the pins of integrated circuit according to the scheme.
5 and 6 to connect to R4, we passed below the IC (integrated circuit), so you do not have the tracks of the IC (PCB) that intersect.
We have, on this first draft, pellets across the LED that it will be connected to the electrical installation by son (in red and blue) and not soldered directly (which saves us, again, d have trails that intersect)
Our CI will be this:
We have shown by their scheme instead of the components ...
Note that we are inspired by the scheme, except for one thing: The resistors R6, R7 and R8 are always in series, as the diagram, but here are placed one beside the other, in order to save space in height. Indeed, if we had followed the pattern carefully and put the resistance one below the other, the circuit was much higher (or larger).
Now that we have this, we find that the assembly itself is fair, but if we return the plate, the "+" is above will go down and the "-" will go up ...
Regardless, this is no problem, but the electronics have become accustomed to the "+" at the top and the "-" at the bottom, either in the scheme or arrangements. This agreement facilitates understanding, and troubleshooting the entire line up is positive, the entire line of the mass is below.
We must therefore reverse the pattern along the horizontal axis. We get this:
Then we remove the drawings of the components ...
And we have this!
Notice I keep No. of components and some brands such as "+" and "-" of the stack, "+" for C2 and C3, which are polarized, and one of the IC.
This is what is called "screen printing" plate. You can do side component or copper side.
The component side to leave us more space and therefore allows us to any other brands ...
You too can screen print your plate. So you can at the time of welding, to know right away the place and meaning of each component ...
The space between the legs of the integrated circuit is 2.54 mm. You can round to 2.5 mm, provided that the next time space is of 2.6 mm, and the way to catch the game for the capacitor, it is the same: follow the no one: 2.54 mm (rounded to 2.5 mm) for C2 and C3, and 5.8 mm (round up to 6 mm) for C1.
for resistors and diodes, allow about 1 inch of space. but for these components, we are not the millimeter: the legs can easily adapt.
For pellets auxillières: those where the battery is connected and the telephone, take the distance that seems appropriate.
Finally, for the LED, you can put the pads wherever you want, as long as one is connected directly (= nothing but a track or disc) to "-" the battery and the other be connected directly to pin 10 or 11 of the IC.
To draw the CI on the plate, you have two solutions: the felt or with self-adhesive pads. In both cases, we need some space between the pellets, such as the CI or capacitors, is correct to the millimeter. I found a great technique:
1 - Get a software integrated circuit design, such as Ares Lite.
2 - Draw the CI
3 - Print making sure that the print scale or at 1 (100%, or 1 / 1 or 1:1 ...)
4 - You get on your spreadsheet, a drawing of the CI size. Cut out the drawing, leaving a margin between the edge of the cutting and the tracks located on each side.
5 - Take a needle and pierce each pellet.
6 - Fix your paper on your plate, copper side, and take a felt
7 - Make a point to the felt on each wafer. Make sure that each pellet out his point, and wait until the felt dry to avoid smudging.
8 - remove the paper. Admire the result: you have a small point on the plate where each pellet should be. these points are located to the millimeter, because the boss is printed from the software.
for the future, you have two options: the felt pads or sticky.
This is what is called "screen printing" plate. You can do side component or copper side.
The component side to leave us more space and therefore allows us to any other brands ...
You too can screen print your plate. So you can at the time of welding, to know right away the place and meaning of each component ...
The space between the legs of the integrated circuit is 2.54 mm. You can round to 2.5 mm, provided that the next time space is of 2.6 mm, and the way to catch the game for the capacitor, it is the same: follow the no one: 2.54 mm (rounded to 2.5 mm) for C2 and C3, and 5.8 mm (round up to 6 mm) for C1.
for resistors and diodes, allow about 1 inch of space. but for these components, we are not the millimeter: the legs can easily adapt.
For pellets auxillières: those where the battery is connected and the telephone, take the distance that seems appropriate.
Finally, for the LED, you can put the pads wherever you want, as long as one is connected directly (= nothing but a track or disc) to "-" the battery and the other be connected directly to pin 10 or 11 of the IC.
To draw the CI on the plate, you have two solutions: the felt or with self-adhesive pads. In both cases, we need some space between the pellets, such as the CI or capacitors, is correct to the millimeter. I found a great technique:
1 - Get a software integrated circuit design, such as Ares Lite.
2 - Draw the CI
3 - Print making sure that the print scale or at 1 (100%, or 1 / 1 or 1:1 ...)
4 - You get on your spreadsheet, a drawing of the CI size. Cut out the drawing, leaving a margin between the edge of the cutting and the tracks located on each side.
5 - Take a needle and pierce each pellet.
6 - Fix your paper on your plate, copper side, and take a felt
7 - Make a point to the felt on each wafer. Make sure that each pellet out his point, and wait until the felt dry to avoid smudging.
8 - remove the paper. Admire the result: you have a small point on the plate where each pellet should be. these points are located to the millimeter, because the boss is printed from the software.
for the future, you have two options: the felt pads or sticky.
- Expand each item on your plate so as to obtain a larger point about 2 mm in diameter.
- Connect the dots, which are now of the pellets, each depending on the design of the IC.
- Check that all the points are properly connected. If two points are then they should not be, clear with a tissue soaked in methylated spirits. If there has burrs, do not worry: they do not resist perchloride.
- Allow the felt to avoid smudging
From now working in a place that will not take the tasks and gown and gloves!
- Fill your container of ferric chloride (liquid!) And immerse your plate. Create light waves, shaking gently to accelerate the burning of the IC. You will need a good 20 minutes. Watch for burning. If the ferric chloride attack a track, get the plate immediately, rinse it well under water, dry and iron the felt. Wait until the felt dry before putting in the perchloric.
- At the end of burning, remove the plate and rinse well under water. Then dry it.
- Remove the felt from the slopes with a cloth or tissue soaked in rubbing alcohol.
- If places are still short, take a knife, or better, a mini-drill (if you have) and scrape. If the tracks have been attacked and there is no contact, repair the track using the copper film. If you have not, you can at the time of the weld and if the cut is not too big, put the gap between the two parties. - Connect the dots, which are now of the pellets, each depending on the design of the IC.
- Check that all the points are properly connected. If two points are then they should not be, clear with a tissue soaked in methylated spirits. If there has burrs, do not worry: they do not resist perchloride.
- Allow the felt to avoid smudging
From now working in a place that will not take the tasks and gown and gloves!
- Fill your container of ferric chloride (liquid!) And immerse your plate. Create light waves, shaking gently to accelerate the burning of the IC. You will need a good 20 minutes. Watch for burning. If the ferric chloride attack a track, get the plate immediately, rinse it well under water, dry and iron the felt. Wait until the felt dry before putting in the perchloric.
- At the end of burning, remove the plate and rinse well under water. Then dry it.
- Remove the felt from the slopes with a cloth or tissue soaked in rubbing alcohol.
- Scrape dishes with a sponge (a sponge "scratchy") plate, including pellets. This will take a very best of the weld.
- Drill the pellets with a forest of a millimeter. If possible, try to target the mid-pads!
- Finally, solder your components and cut the legs that exceeded. Pay attention to the diodes, the IC and capacitors C1 and C2. Do not solder directly to the 4001, but the weld support!
- At the time of welding, so the tracks are cut, you can fix them: each piece of scratch tracks, take a piece of bare wire and solder it to form a "bridge" between the two pieces of track. But the best is still the copper film ... Here's the drawing board layout ...
On the plate, and J1 J2 plug into the holes at the top right. (Those in the middle are left to the battery) Before placing the integrated circuit U1, connect your phone line installation and connect the battery. Make sure it is not placed on the metal, causing a short circuit between tracks.
Then take a voltmeter to a size between 5V and 20V. Place the probe "+" (red) line F, at the foot of R4, and the point of "-" button (blue) on the circuit ground, ie, the level of "less" of the stack (line O), for example, to the cathode of the LED.
With ALL phones on hook (including modem), you should be between 4-6 volts and 9 volts (but certainly not greater than 9 volts). Pick up a phone: the voltage must fall between 0 and 2.7 Volts.
These two conditions are met? Then, disconnect the telephone installation, remove the battery and place U1. Be careful: the mark of U1 should be directed to the line V.
Reconnect battery and phone and repeat the tests: the LED should light up only if the phone is off hook. Got it? So it remains for you to put your mounting box ... (Non-metallic box of course ...).
2 - self-adhesive pads front of you chips and adhesive tracks.
- At the place where there are points to markers, glue a patch. Through the hole in the pad, you should see the point in marker. The pellets of 2 to 2.5 millimeter in diameter are best suited.
At the CI, if the pellets keys, do not worry: we will correct after welding.
- After putting up all the pellets, paste tracks. Choose those that are about 1 millimeter wide.
=> Above all, avoid air bubbles: the pads must be bonded by driving air to the outside (or inside as there is normally a hole). The tracks have to be glued up from one end to another, often by checking that there are no air bubbles that remained: the ferric chloride seeping under any air bubbles!
From now working in a place that will not take the tasks and gown and gloves!
- Fill your container of ferric chloride (liquid!) And immerse your plate. Create light waves, shaking gently, so as to accelerate the burning of the IC. You will need a good 20 minutes. Watch for burning. If the ferric chloride attack a track, you can sadly do nothing. you can always try out the plate, the rinse and pick up the trail sticker, but I doubt you get to do this operation without any problems ... The track will eventually be repaired at the time of welding, especially if you have the copper film!
- At the end of burning, remove the plate and rinse well under water. Then dry it.
- Remove the adhesive tracks
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