(well, the other too)
Belarusian knows what a flicker is. Regardless of social status, age, gender, etc. Naturally, even in jokes, they repeatedly played up this topic. It would seem that with such an approach to business, the death rate on night roads in Belarus would have to rush rapidly to 0, and then generally remain only in the memories. But life judged differently, more and more often in reports of the accident indicated that "the pedestrian was shot down was with flickers." And the point here is that the retroreflective elements sold in each stall with aliexpress are considered not as an element of equipment that can save lives, but as a defense against traffic police fines. Those. "As long as he hung." It is not surprising that low-quality retroreflective tapes quickly cease to retroreflect (and often do not immediately shine with excellent performance). Having active pedestrian parents in a small town, I occasionally thought about their safety and came to the conclusion that instead of focusing on the quality of retroreflective elements, you just need to provide the nurse and the folder with active long-playing light beacons. The topic will be useful not only for night pedestrians/cyclists, but also for pet owners who are prone to night vagrancy (+ “where is the spinner here at all?”). My reasoning on this topic is to look under the cut.
The whole story began with the fact that at the beginning of 2007, the State Aviation Inspectorate of Belarus announced the implementation of the campaign “Minus 100”, the purpose of which was “to reduce the number of people killed in traffic accidents by at least 100 people compared to 2006”. At the same time, personal hinged retroreflective elements, “flickers”, were massively thrown into the sale. In the role of information support were the state media, called upon with their propaganda materials to stimulate the unprecedented demand for these crafts. The progressive part of the population took this, in general, a good idea, with hostility, the fact of the presence of a flicker automatically equated the one wearing to the lowest strata of the population. Perhaps this is due to the fact that initially these "state light reflectors" were from the same sphere as fire detectors/validators in public transport, etc. + disgusting, frilly design/drawing and everything is all (in 5-7 years, by the way, neutral models or just non-cutting-eye models began to appear). The second factor was the fact that despite the fact that the flicker was obligatory to be worn only on dark unlit sections of the road, in the provinces the traffic police caught and fined people without flickers even in an open field (I exaggerate, but not much). It is worth noting that the flickers still did their good deed
by replenishing the treasury with fines
, reducing the death rate on the roads. As a result of the Minus 100 program in 2007, almost 200 people died on the roads less than in 2006 ( of.pruss
). After the completion of the Minus 100 program, the flickers were forgotten for some time, so that later in 2010 a new round would begin ... In general, this is an important topic for the Belarusian society.
Emotions are good, and the facts are better
Despite the negative attitude towards the flicker-madness initiated by the traffic police, I regard the phenomenon of retroreflection as purely positive. If only because it was familiar with the concept since childhood, when the number of “katafots” on a bicycle was an indicator of the “status” of its owner. For those who have forgotten what it is, let me remind you with an excerpt from RU
Katafot (ancient Greek κατα- “prefix with the countermeasure value” + φῶς “light”), retroreflector, retroreflector, flicker (from eng.flicker) - a device designed to reflect a ray of light towards the source with minimal scattering. Retroreflective - the process of changing the direction of the beam by 180 ° using double reflection. When retroreflection, unlike light reflection, the beam is reflected twice.
But those bike katafoty, which was a bargaining chip in most children's exchanges, should be admitted, they were an order of magnitude higher than the whole props that were actively sold and sold now in kiosks and stores under the proud name “flicker”. From a scientific point of view, the main criterion for assessing the quality of a retroreflective material is the retroreflection coefficient (CS). This is an indicator of the intensity with which the light beam returns from the illuminated surface (= the ratio of the brightness of the sample surface to its illumination). The COP is expressed in candela/lux/m 2
(English (cd/lux/m 2
). Naturally, the higher the COP, the better the reflector will be seen on the road. The picture below vividly confirms this thesis:
Clothing color also affects visibility
Well, and visibility? Visibility, in turn, is closely related to the safety of the pedestrian and the stopping distance of the vehicle. All the best GAI-shnik, so it is their retroreflective elements on the vests can act as a reference, their COP should be at least 550 cd/lx/m 2
. And I have no doubt that such figures really exist, since representatives of this profession, as a rule, even have instruments for measuring the reflectivity — retro-reflectometers. In addition to traffic cops, such a toy can be in road builders, etc. professionals involved in reflective road markings/signs. The picture below shows such a device (with considerable, by the way, cost).
With it, you can accurately choose the best reflector. There is no access to the device - you have to rely on luck and hope that the Chinese flicker has done to the conscience. The most common retroreflective materials are either microspheres or microprisms. The retroreflection coefficient of a microprismatic material is tens of times greater than that of microspheres, but the cost is correspondingly higher.
When choosing a flicker, you can additionally be guided by a couple more recommendations:
- white or lemon-colored products (for PVC backing) and gray textile ribbons have the best light reflectivity
- products of the corrugated form are more effective than flat ones because of the ability to work better at wide angles of incidence of light
- images/logos/inscriptions, applied in large quantities on the retroreflective surface, seriously reduce the retroreflection coefficient
- is not allowed when using light reflectors in the form of hinged key fobs, applying a functional coating only on the front side
- with other things being equal, the best retroreflective characteristics have options made using a microprismatic yellow film with combined properties - retroreflection and fluorescence. Retroreflection provides visibility of the optical element at night, and fluorescence makes the optical element brighter in conditions of insufficient visibility.
In general, the simplest the way of testing
of the health of flickers can be a" flash test ": a product made of retroreflective material can be photographed on a smartphone with a flash from a distance of 3-5 meters and see the result.
The correct light reflector will glow bright white (by the way, whatever color the light reflector is, the light reflected from it is always white), fake - it will not glow, well, or it will do it with much lower intensity.
In addition to the probability of acquiring a counterfeit initially, there is such a thing as the degradation of the retroreflective layer with time (= pollution/wear, etc.). Often this piece of retroreflective tape is hung somewhere and people forget about it ... In the end, something like:
A fine, perhaps, such a thing can be avoided, but life may already fail to save ... In addition to hanging elements, this item is very much concerned with working clothes with non-removable retroreflective elements, especially after washing with active detergents in harsh environments.
The second serious disadvantage of flickers is their poor performance in adverse concomitant weather conditions: rain, snow, fog, and cloudy weather. Naturally, these conditions also do not reduce the stopping distance of the car (see the picture, the values are miles per hour and feet of stopping distance, of course, they are not very relevant for the countries of the winning metric system, but I didn’t want to alter the beautiful picture, I would add 1 mile decode 6 km, 1 foot = 0.3 m).
In severe weather conditions, the light from ordinary car headlights, or rather, the rays of the near and especially the high beam, reflected and scattered from the smallest water droplets or snowflakes, create a translucent shroud that reduces visibility (for colloidal chemists, a reminder about Tyndall cone
). When the main headlights illuminate the road, a beam of light is scattered in the fog, partially reflected from the drops, blinding the driver and significantly reducing visibility. This effect is most noticeable in the short-wave part of the spectrum, corresponding to the blue color. Accordingly, when the road is illuminated by a lamp behind a red or yellow light filter, the reflection effect decreases, visibility becomes better. Actively exploit this feature Fog headlights
. Fog, for example, tends to hover above the surface of paved roads at some distance. Therefore, the light of low-mounted headlights is subject to the effect of reflecting light from water droplets to a lesser extent - in this case, the headlights shine “under the fog”, forming a sharply directed light flux at a height of about half a meter from the road surface and highlighting the curb. Rain and snow, by the way, do not have this property.
What can you do in this situation?
IMHO you need to do an active "flicker", i.e. carry a flashlight on me (which I constantly recommend to people concerned about their road safety). Cyclists have a bunch of adapts, a taillight, finally.But what should a pedestrian do?
As a result of reflection, the requirement for a lighthouse was formed:
1) The minimum size (and preferably the minimum number of parts)
2) Powered by one 1.5 v battery (the most extreme option is a 3 v lithium tablet)
2a) Maximum energy efficiency (no Li-ion and microUSB charging)
3) Switchable mode (steady light/fast flash/slow flash)
The first thing that came to mind was a flashing LED. In fact, this is a conventional LED with a built-in integral pulse generator with a flash rate of 1.5 - 3 Hz. You can distinguish it by the image in the datasheet - the arrows showing the light are made dotted
The main disadvantage of such a beacon is that the frequency of flashes is not constant and changes depending on the supply voltage. Plus, to work at reduced power, you still have to do something like a generator blocking. Plus there is no way to switch modes
Next we went specialized chip drivers LED flashers. As an example, LED Flasher IC 1Hz Flashing Driver M34
Here the problem is the same - the inability to control the mode (only a fixed switching frequency of 1/2/8 Hz). Well, I never managed to find these chips for a reasonable price. Apparently, the manufacturer’s case did not go.
The flashing light LM3909 has also become a rare, expensive and overall variant.
Although the thing is definitely worthy: here you have the ability to work from 1.5 V, and the analog control of the flashing frequency. Release its manufacturer in some smd-package and I would be satisfied with this option. But no. As an option, I also considered “LM3909 surrogates”:
As with the use of microcircuits (74HC04-A, 74HC14-B), and especially on transistors (option C), the device, although it can work from 1.5 V, but it turns out even with smd-dimensions rather dimensional. Approximately the same as the flasher on the 555 timer (but in the case of the timer there are power restrictions).
Outside the competition (simply because of the unusual performance) several other devices were also considered. For example, a circuit using a relay:
Neither in terms of miniature or in terms of energy efficiency, the thing did not suit me, but I love these “tube clicks”. An interesting option (also quite energy-intensive, but unique in its power) is flasher
from a powerful LED and a special flashing neon lamp (it flashes due to bending the bimetallic contact plate under heating).
Despite the voracity and size, the device flashes beautifully, like a small beacon ...
under the spoiler so as not to blind (clickable)
Another interesting option (interesting in the light of replacing the wire coils of the blocking generators, because personally I wind the coils to take the last strength) could be the use of a 5252F driver chip (a popular thing for various solar-based designs). Everything would be fine (including the presence of the TO-94 case), but again there is no adjustment of the frequency of blinking.
It would seem that no-no and yes, the thought will arise "Is there really nothing?" The most interesting thing is. And designed, I suspect, in China. This piece is called PET LED and is a device sealed in a ball of elastic plastic, powered by a 3V lithium battery.
Inside, there is a LED, a button, a battery and ... a drop of epoxy compound with a package case.
There are options and non-waterproof performance, positioning itself as a "flasher cyclist." Interestingly, on different types of food - 1x3v or 2x1.5 per
Inside, already traditionally - blah blah blah and a drop of the compound:
Most of those with whom I discussed this issue agree that a microcontroller is filled into the compound. The first thought was, traditionally, arduino. All sorts of lilypads, despite their simplicity and their wearable-orientation, take up a lot of space and require conductors in the form of current-conducting wires. About cheap speech, as you know, is not. Well, LilyTiny on attiny85 also eats energy if not to himself.
And it still needs extra
LED Which LilyPad Pixel Board
Digging on the Internet could not give me an answer to the question “what’s under the compound” and, in general, I came to the point of no return, for which there is only an appeal for advice from the collective wisdom of the habra community. Guys, electronics developers and radio amateurs, maybe someone has thoughts about such a super-simple and super-economical beacon? And is it possible to implement such a miniature device on a microcontroller, which, together with the LED (smd), would have enough voltage of 1.5 volts.Atiny 13 or pic10 available in our area, according to reviews, do not really want to work at low voltages, fail and turn off peripherals ...
: an interesting version threw drWhy
. This flasher
from the spinner. I immediately liked this idea, because it meant just what I needed. But suddenly, trying to find a spinner (!) In Minsk, I was faced with the complete absence of such pieces. They disappeared in one fell swoop (more than a month ago spinner-madness was observed everywhere, from underground passages to airports). We managed to catch the only suitable model for disassembly in Gorky Park. Suitable = such in which the chips would not be poured into the compound (I had to open the case and check it so as not to take the next cat in the bag). As a result, such a thing was found, three miniature flashlights in sealed enclosures - for only $ 1.5. You can take and use. So far this is the absolute leader in price (even without taking into account the fact that it is possible to take three (!) Spinners with three beacons in each for $ 1.5).
Inside were three LEDs of different colors, a button, a microcontroller (?), Or some tricky LED driver + two LR1130 batteries. The approximate scheme looks something like this:
It’s true to establish what this “TX-333” thing is (I didn’t manage to find the datasheet accordingly) ... it really reminds some of the attiny10 or pic10, but I can’t confirm :)