Wind detection board - First version

An automatic device protects a blind against the intensity of the ambient wind. It allows the definition of a threshold from which the wind speed is supposed to be dangerous for the structure of the blind ( the fabric as well as the arms ... ). This device must be able to present a setting of this threshold over a wind speed range from 20 km / h to 50 km / h.

image of a wind sensor ...Here is the first module of this application, which will include at least three, one for each element ( wind, rain, sun ). This is a Frequency / Voltage converter, which transforms the speed information coming from the wind sensor into a voltage proportional to ... this speed, precisely! This information is directly proportional to the wind speed.
schema eoleThe sensor is of the reel type with 3 star cups ( or cups ). It allows reliable measurement regardless of wind speed. The conversion into an electrical signal is done by ILS type contacts ( 2 pulses / revolution ). The rotation of the reel drives two permanent magnets which modify the state of the ILS. By clicking on this link, you will be able to see an exploded view in color of all its components.




Operation detail:

The sensor which already has a 1KΩ series resistor internally is supplied through a 1.5KΩ resistor ( R202 ) serving for its polarization. Thus, upon rotation of the anemometer, the resulting output value is almost V alim / 2, or about 2.5V peak. This signal is rectangular in shape ( its ideal duty cycle would be 50%, but this is not quite true, probably because of the magnetic disparity provided by the 2 magnets ... checked with the oscillator, I get 57.66% ... ).
The cell composed of the diode D202 and the resistors R203 / 204 constitutes a voltage adapter. The second cell, composed of resistor R205, capacitor C203 and logic gate IC202A constitutes aintegrator assembly ( low pass filter ) . C204 and R206 constitute a shunt assembly ( high pass filter ) . The shunt assemblies are generally used as a trigger control of a monostable latch. Using this filter, we will be able to detect the pulses on a rising edge, and to format them using a Schmitt trigger ( IC202B ). This makes it possible to obtain a perfectly stable signal. An oscillator circuit composed of an NE555 ( wired as a monostable circuit ) and an RC circuit ( P201 + R207 + C206 ) delivers a pulse type signalthe duration of which in the high state depends on the setting of P201, for each pulse coming from IC202B. Ultimately, the output of the monostable will only deliver a pulse when there is a signal present at its input. Potentiometer P201 therefore makes it possible to select a working window. That's the whole point here. This signal will then be converted into a voltage, voltage directly proportional to the frequency of what comes out of the NE555. This voltage will then be applied to an operational amplifier ( LM741 ), the threshold of which is adjustable thanks to P202 + R209 + R210. A 1.8MΩ resistor provides a gain to amplify the resulting signal. A new formatting thanks to IC202C, then attack of a transistor BC547 ( T1 ) througha 10KΩ resistor (R213 ), R212 and R214 serving as a polarization at its base. The output is made on the collector via R215 and its signaling light emitting diode.
In this configuration, we obtain on pin (1) of K203 a high state ( + 5V ) at rest, and a low state ( 0V ) when the wind speed exceeds the threshold set by P201.

Food :

The assembly is supplied through the voltage regulator IC201 for 5V, the 12V coming from a supply circuit common to all the modules. For reasons of performance and beyond energy saving, I have indeed opted for a power supply of type SMPS ( switching power supply ). This type of power supply operates with an efficiency of more than 80%, displays a minimum of losses and overheating, and offers protection against overvoltages, all this thanks to high performance components. In addition, their operating range is wide (from 85 to 264V approximately, and at a frequency of 47-63Hz), which allows use in all latitudes!

Modification [Edit of 09/27/2013]:

With my troubles of parasites which I could not find the origin, an idea suddenly appeared to me!
I took a closer look at the datasheet of the HEF40106BP integrated circuit, and I noticed that its supply voltage could go from + 3V to + 15V ... I therefore modified my card so that IC202 is supplied with + 12V, and surprise ... no more parasite at all!
In fact, on my diagram there is mention of a CD40106, the CMOS version of the HEF40106BP, and which is supplied to it at + 5V, hence my problem!
The easiest way is to remove the 7805 regulator, and switch everything to + 12V, with very few modifications ...
In this case, you will have to modify the value of R202 (1.5K) by passing it to 3.9K , cut the feed track ( pin 14) of IC202 using a simple cutter, and connect this pin directly to + 12V. On the other hand, by proceeding in this way, the green Led will no longer light up, since it is powered by the potential difference between + 12V and + 5V!
The Led consuming around 10mA, replace R201 (680 ohm) by a resistor of 470 ohm, and connect the Led + resistance series assembly between + 12V and ground.
That's all, now the editing only works with a + 12V power supply, so you will save a few euros while keeping the same turntable, if you have already engraved it ...

Schematic diagram :

picture of the block diagram of the module

Production :

The assembly of the plate does not call for any particular remark, except that it is better to start by soldering the vias replacing the metallized holes ( to do this, use pieces of resistance legs, for example ... ) . Then solder the tulip supports ( or lyre according to your choice, but it is not recommended to directly solder the integrated circuits, because it is easier to unplug than to unsolder the component during a breakdown! ).

You have finished ? Well done ! Now remove all the integrated circuits, only the 5V regulator and the transistor should remain as active components.
Arm yourself with a voltmeter, and connect the + 12V to pin 3 of connector K201 (this is the fuse entry ). As soon as this is done, the green Led should light up ( if this is not the case, unplug immediately, and check your connections, the polarity of the power supply, the absence of short circuits, etc. . ).

Test on the IC sockets for the presence of + 5V and / or + 12V on the supply tabs, namely:

Semiconductor power supply table
  IC202 IC203 IC203
+ 5V pine 14    
+ 12V   pin 4 pin 8
GND pin 7 pin 1  

If you do not get this result, there is a problem with the PCB itself ... it will be reviewed!
Check earth continuity with an ohmmeter when de-energized. We are never safe from a micro-cut, perhaps due to too long exposure in iron perchloride ...

All this is absolutely necessary before proceeding with the final power up!
You have arrived at the end of this test, the next episode will be the development ...

Photos of the module:

photo of the plate seen from the components side ...photo of the plate seen from the welds ...
This is a prototype on which I have already made small changes ...

Connections :

The links below will allow you to download the diagram and the artwork in PDF format ( scale 1:00 )

Note : The version numbers may differ between the block diagram and the typons, and do not necessarily have a relationship between them. The files that I placed on my site are indeed the most successful versions.
link.gifLink to the PCB manufacturing site I used
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