The perfect self-controlled watering system PIC18F4550 PIC12F509 HD44780

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Preface

Fig.1 - The boxed HD44780 LCD display

Fig.1 – The boxed HD44780 LCD display

I want to clarify from the outset that this is an ambitious project. Making a watering system that interacts with the environment and autonomously decides if it will irrigate some plants and how long, is not a trivial matter. For this reason, even if the version 1.00 works quite well and it is already operative in my balcony, probably many others will follow soon.

The concept is not far from the project BP0001: watering triggered by the sun and not by clock time, multiple watering zones, same economic 24V AC solenoid valves, same water piping system. But, as you maybe already know, the BP0001 is a good solution only to buffer for a short time frame (ex. a holiday). Indeed, the code is too simple, based on the knowledge I had at that time, and the watering system does what it needs to do as long as the environment remains unchanged. But that’s the point, that’s the limitation to overcome, that has become my goal.

Fig.2 - The perfect self-controlled watering system with the PIC18F4550 (without the display)

Fig.2 – The watering system

So, I have decided to make a system with a temperature and light transducer, controlled by a powerful MCU, such as the PIC18F4550, and with the possibility to add some more devices on its inputs.

The PIC also has to drive a 16×2 LCD display HD44780 (figure 1) in order to monitor the situation and manage the watering more easily. In addition, a smaller MCU has to keep under control the work of its big brother and intervene if something goes wrong with it. On figure 2 you can see the watering system (without the display).

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Original cheap transformerless UV-LEDs bromograph PIC12F509

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Preface

Fig.1 - The UV-LEDs bromograph during the exposure

Fig.1 – The UV-LEDs bromograph

A bromograph (or UV Exposure Unit, or UV Screen Exposure System) is a fundamental instrument for making PCBs using the photo-etching method. Unfortunately its price is usually prohibitive for a normal DIY maker and the UV-neons are expensive anyway if you’re thinking of building one.

I thought that UV-LEDs could represent a valid alternative to them and I made some experiments to test their effectiveness. Encouraged by the first positive results, I considered that even using UV-LEDs with a wide view angle, such as 120°, I would need 54 LEDs to light uniformly a surface of a common 160×100 mm board. That means at least 1A of current consumption or doubling in case of a dual-layer bromograph, plus, a small amount consumed by a timer circuit which I planned to include in the project. So, I decided to avoid the use of a transformer that is quite cumbersome and expensive. I surfed on the internet looking for a solution and I stumbled on Wutel‘s website. There, I found some circuits that, by exploiting the capacitive reactance, supply LEDs directly from the 220V.

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Versatile 0.01Hz to 100KHz Analogue Function Generator XR-2206

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Preface

Fig. 1 - Front view of the analogue function generator

Fig. 1 – Front view of the analogue function generator

The XR-2206 from Exar© is a great IC because, with a few components, it makes it possible to build a circuit that generates analogically various waveforms with a frequency from 0.01Hz to 100MHz. This capability allows you to build quite easily a function generator useful to test audio devices and all the circuits that require a low frequency input.

By exploiting the characteristics of the IC, I provided the PCB with two outputs: one suitable for testing analogue circuits, one for testing digital ones.

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Multi-Frequency Second-Order Active Crossover for Subwoofers NE5532

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Preface

Fig.1 – The multi-frequency second-order active crossover for subwoofers

Fig.1 – The multi-frequency active crossover

The project offers an universal solution that allows you to find and set the best cutoff frequency for an audio system’s subwoofer with no special equipment. Beyond this, in my opinion, practical listening is the best way to compare audio configurations and devices: charts, parameters and calcs are very important but they may not be respected when put into practice.

This crossover gives you the possibility to set six different cutoff frequencies: 63Hz, 80Hz, 100Hz, 125Hz, 160Hz and 200Hz. The right selection is the one that will make your audio system sound better.

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Intelligent bi-colour backlit LCD display’s thermometer ICL7106 PIC16F84A LM324 74HC148

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Preface

Fig.1 - The thermometer with the green backlight

Fig.1 – The thermometer with the green backlight

What I’m getting ready to explain below, is an original solution I adopted to backlight the thermometer’s project SP0003. Thanks to this, I solved quite easily the main difficulty that consists in generating an even illuminated background to the LCD display using some common LEDs.

At that time, I was also learning how to use the microcontrollers and I wished to make my first real project (and not only on a breadboard) with the PIC16F84A. I programmed the µC for changing the backlight’s brightness according to the room’s light intensity because it could be annoying in the dark, or insufficient in the opposite condition. I also thought that it could be nice switching the LCD backlight colour by pressing a push button.

To complete the project, I inserted a power supply to the thermometer capable of accepting a wide range of DC or AC voltage.

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Compact 2A 0-30V Variable Switching Power Supply with Current Control L296

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Preface

Fig.1 – The compact 2A 0-30V variable switching power supply with current control

Fig.1 – The switching PSU

This is the PCB I used to test all my projects.

When I drew it, I took the cue from the project published on electroniq.net (I hope the attribution is made to the right author because I found many clones on the internet). I changed something on that schematic making the improvements I thought were right also in order to try to use the components I already had available.

To be honest, what makes the project so good is not this specific schematic. That is nothing more than an elaboration of some “typical applications” suggested on the L296‘s data sheet, but the IC itself.

The l296 switching regulator requires very few external components and the current limiter is already inside it (make sure to use the L296P to take the advantage of this function).

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Phase shifter for bridging two amps NE5532

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Preface

Fig.1 – The stereo version of the phase shifter for bridging two amps

Fig.1 – The stereo version of the phase shifter

As declared on the last post, I have published a very recent project, built after the andy-progetti website’s birth.

This circuitry is an elementary phase shifter but I think it represents the best solution for bridging two amplifiers. I don’t know if you already know the theory of bridged amplifiers, otherwise, on the Wikipedia’s website, you can find the main information about it.

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Coming soon! Most recent projects ready to be published

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So far so good: andy-progetti‘s website was born almost 6 months ago, as many projects have been published, and visits are slowly increasing. Thanks to everyone for that.

I still have various projects ready to be published but I have also lots of new ideas in my mind. I have found enough time to build some of them, so, within ten days, I should be able to publish one of the most recent project.

Basic JDM PIC Programmer

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Preface

Fig.1 - The basic JDM programmer

Fig.1 – The basic JDM programmer

Some years ago, in order to make some experiment at home with the PIC16F84A microcontroller, I needed to build a programmer. Surfing on internet I found lots of solutions and I decided to realize one of the easiest ones: a JDM programmer.

The cost of the project is probably a couple of Euros. In the PCB in figure 1, I used only components I had available at home and for that reason the DIP socket is 20 pin instead of 18.

I remember leaving the schematic as it was and drew it directly on Eagle, as shown in figure 2. Today I tried to find on the web the original project with no success. A similar one is published on the PICPgm‘s website (figure 3) but others are available on various websites as well. So, I don’t know exactly who to thank for this :-)

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Three-ways Automatic Watering System PIC16F84A

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If you are interested in buffering for a short time frame (ex. a holiday) this is the right solution for you, otherwise go to the project BP005 for a self-controlled watering system that operates 365 days per year.

Presentation

Fig.1 – The three-ways automatic watering system's central unit

Fig.1 – The watering system’s central unit

Some years ago I had the opportunity to spend a whole month holiday in Portugal. I didn’t want to ask my friends, or neighbours, to water my plants everyday for me. I thought therefore to build a system for that purpose using the most common microcontroller PIC16F84A.

I thought and tested lots of different solutions in order to find the best one. Reliability was the most important aspect to ensure: a fault could have killed my plants or, worse, flooded my neighbour’s house. Once the system was built, only a few days remained before my departure. So, I set the irrigation timing as best as I could, I asked a friend of mine to go and check once if everything was fine and I left the house crossing my fingers.

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