ARTICLE NOT COMPLETED ...This module can be compared to a twilight detector, however, it works in a wider operating range since it detects the level of the sun as soon as it rises, until sunset. The main advantage of such a system is to protect a terrace, a room, or even plants and / or flowers placed behind a bay window, from the sun's rays, for example ( which is my case ... ). Thus, the blind will automatically come out when the rays are too strong, to retract just as automatically in the event of twilight. It goes without saying that the functioning of this system depends directly on the 2 other natural elements. In the event of strong wind or rain, or even both, it is obvious that these two parameters prevail.
Operation detail:A photoresistor (LDR) polarized by R302 provides a DC voltage directly proportional to its illumination. This voltage adapted by the divider bridge formed by R303 and R304 arrives at the input (+) of an operational amplifier IC302. The network of resistors formed by R305 / P301 / R306 then R303 provides an adjustable reference voltage on the input (-) of the AOP. The gain of the stage is set by R308 at around 20. When switching this output, a positive voltage comes through R313 to bias the transistor T1 (NPN) of type BC547, thus illuminating the LED302 to indicate this change of state.
The advantage of this indicator is in fact only useful during calibration, thus making the threshold detection adjustment more practical.
This same signal is adapted by R309 to then be sent to the input (-) this time of another AOP (IC303). The hysteresis of this chain is fixed using a new divider made up of R310 / P302 / R311 then of R312. In order to obtain a flawless logic level, the output attacks the input of a Schmitt trigger, which itself through R315 controls the base of a transistor T2 (NPN). On the high logic level of its base, it conducts, thus delivering a perfect high state to its collector, thanks to the polarization resistor R316. The LED303 light-emitting diode lights up, signifying this state.
Food :The assembly is supplied through the voltage regulator IC301 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. 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 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!
Schematic diagram :
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 K301 (this is the fuse input ). 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:
|+ 5V||pin 11||pine 14|
|GND||pin 4||pin 7|
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 :
The links below will allow you to download the diagram and the artwork in PDF format ( scale 1:00 )
- The principle diagram
- The designs, including the component layout diagram and the drilling plan
- List of components List of components ( XLS format )
Link to the PCB manufacturing site I used