. Introduction

Certainly, the idea of making some kind of advertisement with leds is not new. In the past years very bright leds have appeared that make possible these advertisements, visible from long distances, even hundredths of meters, with effects comparable to those of neon lights, and that as will be shown you can build at your home, with patience and dedicating several hours of work.

A simple static advertisements won’t get too much peoples attention. It will be seen how to make a flashing or, better, a dimming effect without special knowledge of how this works or about the electronics needed.

On figure 1 (aspect and detail from 150 m) appears the realization of an advertisement meant for advertising an apartment being sold, as seen from about 150 m, and the detail of it. At the right, “SE VENDE” is “FOR SALE” in spanish. The letters are made with panel leds and have a dimming effect. At the left appears the surface of the apartment and a contact phone, made with led strips; they are fixed.

See it in action in Youtube, recorded 660 m away:

Be sure to watch it in Youtube full screen at 1080p.

Note that what is meant for catching the attention are the big letters at the right with the dimming effect. When someone sees them from far away that there is an apartment being sold, and advertised in such a way, he will possibly come to get information and will see then the contact phone.

The sizes for letters and numbers used here are based on A1 sheets (594 x 841 mm) at the right and A3 sheets (297 x 420 mm) at the left. All elements are on the inside, so rain is not a problem. The dimensions are dictated by the size of the windows; see that at the right each letter is as wide as the window permits, and at the left the information is restricted to the space available. Logically, if you decide to make a similar advertisement, your dimensions will be different.

As said, panel leds are used for the big letters at the right. They required more work than the numbers made with led strips. For a smaller advertisement you can consider only using led strips. All will be shown with detail later.

The ideas for advertisements like this are not limited to the “FOR SALE” type. “GARAGE SALE”, “BAR”, “FEAST HERE”, etc, are othe possibilities. Also, note that occidental fonts seem suitable for use of panel leds; if you want an advertisement in japanese or chinese, possibly you will use led strips.

Possibly you can find letters already made based on SMD leds, even for outdoors, but may be expensive or not of the required size, or simply that you want to make them by yourself. What is exposed here does not want to compete or be compared with scrolling panel leds, pixel leds, P10 panels, EL wires and tapes, etc.

Step 1: Led Basics

For all that follows, will be considered only panel and strip leds fed by a 12V DC power supply. For that, leds are grouped in sets of three connected in series and with a common resistor; the resistor can be made common to several sets of three leds in the case of panels, implementation depending. Each panel led has 3V voltage drop (more on led strips), so expect 25% power losses in the resistor. This is not efficient. For your peace of mind, be informed that if your house or office has led lighting it will normally use leds fed by 300 or 350 mA current sources (not 12V voltage sources) with negligible power losses, with power factor close to 1 and with low current harmonics generation.

On figure 2 (PWM activated leds) think about closing and opening the switch. If continually open, the leds will be off; if continually closed the leds will be fully on. If you close and open it slowly, you will get a flashing effect, which may be disturbing. If you close and open it fast at least 50 times per second (to avoid flickering), and say it is half the time open and have the time closed, the leds will shine with half the full brightness. If you vary the relative time it is open and closed you will have the dimming effect; technically it is called PWM (pulse width modulated) control. For that you need electronics, normally an electronic switch (transistor) and a microprosessor varying some internal timer controlling that switch. Fortunately, you can find the necessary components already built and at incredibly cheap prices.

On figure 3 (panel (5 mm 'Piranha') and strip (SMD) leds) you can see different 12V panels and strips you can use for your advertisement: 12x8, 6x8 and 3x8 5 mm leds (‘Piranha’ type) panels, and quadruple and single line SMD led strips. Here will be used 6x8 leds panels and single line strips. Note clearly on the strips the arrangement in sets of three leds; the dark points are for cutting and soldering as needed.

On figure 4 (panels rear view) you can see the arrangement in sets of three leds (better seen in the 3x8 panel) and that the resistors are of the SMD type for this particular 6x8 panel, which are power resistors grouped for the other panels. That is implementation dependent and you won’t have to worry about. The panel used here will be the 6x8 leds one. Note that they are sold without cables (as appears on the 3x8 one). Use rigid wire 0.5 mm thick as shown here; that will greatly facilitate soldering (note that once fixed the panels won’t move, so rigid wire is valid).

Step 2: Current Measurements

For dimensioning the 12V power supply, cabling and decide if you need amplifier you have to know power consumption. On figure 5 (panel current measurement) the consumption of a 6x8 panel (the one used here) is measured, fed with a Lipo battery; note that current (continuous) is measured magnetically, even being continuous current. So a 6x8 panel needs 260 mA.

Led strips power consumption is specified in watts per meter. It depends mainly on led type and density. For single line strips led type 5050 or 5630 at 60 leds per meter power consumption is 75 W/m.

As will be seen, here will be used:

  • 71 panels, which will need 71x260mA=18.46A. At 12V: 221W.
  • 8 meters single line strips (5630): 120W.

So approximately the power supply should be of 341W at least. One of 360W was available.

It was observed, however, that led strips in practice consume less. Figure 6 (strip current measurement and connections and SMD leds detail) shows the “1” number using 0.5 m of a 5630 led strip fed with a Lipo battery at 11.23V, needing 330 mA or 3.7W. So 8 m would need 59W. A detail with three leds with its 39 ohms resistor occupying 50 mm (so the will be 60 leds in one meter) is shown. In those working conditions each led showed a voltage drop of around 3.25V, so the current at 12V should be (12-9.75)/39 = 2.25/39 A and for 0.5 m 22.5/39 A = 577 mA or 111 W for 8 m strip at 12V. In practice there are a few tenths of a volt lost in the copper of the strip, which further reduces current consumption.

Note that when dimming turns off the panel leds consumption decreases, but the power supply has to be dimensioned for the maximum current, or it would could limit current due to its protections.

Also in figure 6 note the connections to the strips, from strip to strip with rigid wire and to the power supply with thick flexible wire. This will be seen later.

So with these ideas about leds, we can go ahead. On the following practical important details for your advertisement will be described.

Step 3: Materials Needed

You will need part or all of the following (se figures 9, 10 and 11 later on):

  • Panel leds.
  • Strip leds.
  • Dimmer controller and amplifier.
  • Power supply.
  • Rigid and flexible cable (red and black).
  • Tinned copper wire.
  • Screw terminals.
  • Plastic net.
  • Suckers with hook.
  • Soldering tools.
  • Miscellaneous: ties, wire cutter, wire stripper, multimeter, adhesive tape.

You can get the panel leds, the strip leds, the dimmer controller and the amplifier in Aliexpress, Amazon or Ebay. Since the dimmer controller and amplifier are so cheap, be sure to order some spares, as they can be destroyed in case of a short circuit. By far, most of the total cost will correspond to the panel leds. You can find the rest of the elements in electronics or hardware stores.

Step 4: Decide Your Advertisement

As mentioned, considering window sizes and possible visibility, it was decided to use 6x8 white panel leds for the letters in “SE VENDE” covering A1 sheets (with good visibility 500 m away), and numbers formed with single line led strips covering A3 sheets (with good visibility 200 m away). The main cost would be the panel leds, each around US$4 in sets of 10. Consider double of that for 12x8 panels, and half for 3x8 panels. If you really want big letters covering bigger sheets you can choose 12x8 panels, but the costs can be prohibitive.

For smaller advertisements, instead of using 3x8 panels, you can choose quadruple strips, as those in figure 3. They were not used here, but can make life easier.

Note that the leds in the panels used here are 5 mm leds type ‘Piranha’. There are similar panels with SMD leds; ‘Piranha’ panel leds are preferred.

For the following we will consider separately the panel letters part, and the strip numbers part. The first one, as will be seen, is more complicated.

Step 5: Design Your Advertisement

The advertisement will have simple letters and numbers, so you can base them on the very simple PV fonts as shown.

So make a document with one letter per sheet and increase font size filling the sheet as much as possible, and have it printed. For the examples here, possibly you can print A3 but not A1, so print it at a copy center or similar.

Figure 7 (sheets preparation) shows examples printed on A3 and A1 sheets with PV fonts, filling the sheet as much as possible. The strips and panels are shown attached: that will be explained later.

Step 6: Connections Explained

In figure 8 (strip, panels, dimmer controller, amplifier and power supply with cabling) appear the connections with screw terminals to the led dimmer controller, amplifier and panels, and to the leds strip. According to expected amperes, the cables to the panels are 2 mm thick, and to the strips 1.5 mm thick. Note that, as will be described later, three of the seven letters will be connected to the dimmer controller, and the other four to the amplifier, and each is connected to the power supply through its own cable.

Note also that this 360W 12V power supply has a fan, which makes some noise. In fact, because of the panels dimming the fan speed changed.

Figure 9 (dimmer controller and amplifier connection) shows the connection to the dimmer controller and amplifier. The amplifier takes as input the output of the dimmer controller and feeds its panels. In this way all the panels are synchronized, and you can connect as many panels as you want: one dimmer controller and as many amplifiers as needed (here, as will be seen one amplifier was enough).

Figure 10 (dimmer controller, amplifier and screw terminals) shows dimmer controller and amplifier in detail, as well as the screw terminals, to be used in sets of two (positive (red) and negative (black) terminals). Note that the amplifier has two inputs: power supply (labelled) and signal to be replicated.

Step 7: Miscellaneous Materials

Figure 11 (miscellaneous materials) shows:

  • Screw terminals (pair).
  • Adhesive tape.
  • Suckers with hooks.
  • Rigid naked thick tinned copper wire (2 mm thick), for interconnecting the panels in each letter.
  • Rigid isolated rigid wire (0.5 mm thick) black and red, for connecting panels and strips.
  • Timers. Used in case you don’t want the advertisement to be on all the time. A mechanic (daily) and a digital one (weekly) are shown.

Figure 12 (plastic nets) shows the plastic nets that will hold the panels and their connections with small ties, that you can see in figure 7 (right). The green one was chosen, but you may prefer the white one, since it will be easier to align the panels with it.

Step 8: Strip Leds Numbers and Letters

The strip leds numbers and letters will be described first, since they are easier to make.

On this advertisement the strips supply information (contact phone and apartment surface), don’t need to be seen too far away, and have no dimming effect (they are directly connected to the power supply).

After you have the sheets (here A3) with all letters and numbers or whatever you want printed, you can roughly calculate the length needed. For easy cutting and soldering order strips without plastic cover. Order strips with 5050 or 5630 leds, cold or warm as desired.

The strips are adhesive, so simply cut them where indicated (line close to scissors sign), fix them to the sheets beside the text, and interconnect the number or letter segments with the rigid red and black wire 0.5 mm thick, soldering small cables. The reason for fixing the strips not covering the text will be explained later. Be prepare to dedicate time to each letter or number, and this time multiplied by all letters and numbers will result in a few hours. Be patient.

After finishing all numbers or letters, you will have each in a sheet of paper, and you must prepare the connections from one to the next in parallel with the red and black flexible wire. Prepare two cables for each number or letter (except the extremes), each going further than the sheet width. Try to do the connections at the overall center, for minimizing voltage drops, and with the two connections close together. See previous figures 6 (detail) and 7 (left).

Attach the screw terminals (pair of contacts) to one of the cables. The correct way to do this is so that the output cable to the next number or letter has the screw terminals on it. Test each letter connecting the cable briefly to the 12V supply. Note that if you put some tin on the tips of the flexible cables it will be easier to introduce them on the screw terminals.

All numbers and digits will be connected in parallel to the power supply. Do the connection at the middle of all digits and numbers: if you do it at one end, that end will carry all the current and may get hot.

Finally, fix letters and numbers (in this case with tape to the windows) and connect them (red with red, and black with black). If you tested individually numbers and letters there should be no problem. If everything is working, touch the strips: the ones close to the power supply may be hot. Measure the voltage, speacially at the extremes: a drop of a few tenths of a volt is admissible.

Step 9: Letters With Panel Leds and Dimming Effect

First, you must estimate how many panels you will need. You can do that with a drawing program, first writing the text with PV fonts, and then erasing as needed, or printing the letters in A4, cutting rectangular pieces of paper as the panels but scaled, and placing them on the A4 sheets.

What was done here was the drawing method, as figure 13 (panel letters design) indicates.

So 71 6x8 panels had to be ordered.

Purchase the plastic net to hold the panels in meters. Here, for seven letters on a A1 size of width 594 mm 4.2 m were needed. Note the reasons for fixing the panels and the connections on these plastic nets:

  • The panels would be fixed with ties (two each) on one side.
  • All the connections would be on the other side (also using ties as will be seen).
  • Each letter would be fixed to the window with suckers (at least five per letter) with hooks, and the hooks would go through the net holes.

The panels come without cables, so the first will be to solder red and black pieces around 15 cm each of rigid wire 0.5 mm thick to their connecting holes; note that rigid wire facilitates introducing the wire and soldering it. Also note that for the 71 panels considered here you will need almost 11 m of each color.

Then, having printed the letters (here in A1 sheets), and having cut the plastic nets, place the panels over the letters and over the plastic nets, and fix each panel with two ties diagonally opposed.

Be careful so the letters have equal height. In figure 1 note that this was not taken care enough, and when everything was finished this failure became apparent.

With all panels fixed with ties, you can pass the panels cables to the opposite side of the plastic net and start connecting them. Figure 14 (panels connections inside a letter) indicates how to do it.

Observe in figure 14 wires of three different thicknesses:

  • The connections to the panels are the pieces of rigid wire 0.5 mm thick.
  • The vertical lines represent naked tinned copper wire 2 mm thick. They must be placed near to the panels, at least separated 30 mm and fixed with ties along all their length to avoid shorts.
  • The horizontal thick connections connect the letters to the dimmer controller or amplifier and to the next letter. As mentioned for the strips, input is at the left and output at the right; the square represents the pair of screw terminals. The letters at the extremes only have the input connection.

With all panels fixed to the plastic net, place the naked tinned copper wires moreless close to the panels, and solder the panels wires to these wires. Then, solder the external connections (flexible 2 mm cable). While soldering, keep the plastic net separated, so as not to melt it. When finished, fix the naked tinned copper wires to the plastic net with ties, to keep them in place. See figure 15 (panels fixed, soldering and wires fixed) for this done on a complete letter.

Figure 16 (panels fixed, soldering, and wires fixed (detail)) shows it in detail.

As mentioned before, and as will be explained later, three letters will be connected to the dimmer controller and four to the amplifier; with thick connections it is not too important to start the connections in between the letters if the distances are short. With everything in place, solder the wires and test each letter. Fix the letters to the windows with the suckers and interconnect them in parallel, and connect the three and four letters to the power supply for testing (the dimmer controller and the amplifier will be connected in next step). For details of the connections, see figure 17 in next step.

Don’t use tape for holding the letters. Each letter weights around 600 g, and in the first tests with tape the letters finished falling (if one letter falls it will pull its neighbours). In addition, sunlight may degrade the tape. Suckers lasted forever. Use at least five suckers per letter. If you want, you can reinforce sucker fixing with tape.

After having fixed and tested the letters, put the A1 sheets with the letters printed over them; you can do this with tape. This may not be considered necessary, but it was observed that as the sun moves along the day, when the angle of the sunlight is low in winter, and is perpendicular to the panels, the leds are not seen at all. In that case, the visibility of the advertisement will be given by the black letters. This applies also to the strips.

Step 10: Connect Dimmer Controller and Amplifier

According to their descriptions, the dimmer controller and the amplifier can supply up to 12 and 10 amperes, respectively. Previously, it was seen that the maximum current for all panels would be up to 18.46A. So it seemed adequate to connect the dimmer controller to the first three letters and the amplifier to the other four.

Figure 17 (letters connections from inside) represents schematically all letters connections seen from inside (the letters would be seen inverted horizontally, as indicated). In it the following can be distinguished:

• PS is the power supply, C is the dimmer controller and A is the amplifier. The output of the dimmer controller goes to the input of the amplifier.

• The small rectangles are screw terminals.

• The big rectangles are the letters. Inside them, the vertical lines represent the nude rigid tinned copper wires to which the panels (not represented) are connected.

• Letters are connected in parallel to the dimmer controller or to the amplifier.

Figure 18 (panel letters connected, fixed with suckers, and covered with A1 sheets (inside)) shows several panel letters from the inside. The plastic nets hang on the sucker hooks. As explained previously, for better visibility with direct sunlight, they are covered with A1 sheets with the letters printed, fixed with adhesive tape.

Experiment with the buttons of the dimmer controller, varying its program, speed and brightness. You can get a flashing effect, but dimming is less disturbing.

As with the led strips, check voltages; again a drop of few tenths of a volt is admissible. Also check the temperature of dimmer controller and amplifier; they may be a little hot. The power supply should include a potentiometer to adjust its output voltage, and hence the overall brightness.

Dimmer controller programming is not lost when power goes off, so you can connect the power supply to mains with a timer (a daily (mechanical) or a weekly (digital) one), in case you don’t want the advertisement on all the time.

On figure 19 (dimmer controller and amplifier connections) appear the internal connections of dimmer controller and amplifier (those in figure 10). The power positive terminals are common.

As you see, a very flexible advertisement has been described, made with dimming panel leds and fixed led strips (of course, you can also make led strips dim). You can adopt it to your wishes and your needs.

This advertisement is supposed to be fixed to the windows on the inside part, protected from rain. Rain protection is not intended here.

As appeared at the introduction, if you want to see this advertisement in action in Youtube, the link is:


Be sure to watch it full screen in full HD.

If your advertisement is in an important city it may eventually appear in Google Street View or Microsoft Streetside. Figure 20 (Street View capture) shows it.

<p>It would be really fun to make these as a series of fan signs at a football game. It would be visible throughout the whole stadium.</p>
<p>Yes, that seems a good idea. You can carry a 3S LiPo battery as supply, and it should last the whole match. If you want to be noticed, use the dimming effect. Probably, using quad row led strips you can make nice and visible dimming signs without too much effort.</p>

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